What is the hygiene hypothesis and what does it have to do with food allergies

170 foods are allergens, but most reactions are triggered by just a few foods. The most common allergens are cows milk, eggs, peanuts, nuts, soy, wheat, fish and shellfish[6, 18].

Fish and shellfish allergy

A fish allergy is often only seen in adulthood. Affected people generally cannot tolerate any sort of fish. Most fish allergic individuals, however, can easily eat shellfish and vice versa.

Shellfish allergy also generally develops during adulthood. Shellfish include every crustaceans, including crabs and lobsters, molluscs (snails), including oysters, scallops and squid, as well as insects such as cockroaches and locusts.

Since house dust mites are crustaceans, shellfish allergy sufferers also often reply to home dust[20].

Spice allergy

Spices are found in every sorts of processed foods, cosmetics and dental products. However, they do not own to be marked on the packaging. This makes it hard for allergy sufferers to avoid certain spices. However, spice allergies are relatively rare. The most common are allergies to cinnamon and garlic, but more rarely there may be reactions to black pepper and vanilla[28].

Nut allergy

In nut allergy, doctors distinguish between allergies to peanuts — which are actually legumes — and other nuts that they refer to as tree nuts.

Every nut allergies tend to trigger relatively frequent violent reactions that even extend to anaphylactic shock[26,27].

Cow’s milk allergy

Cow’s milk allergy is the most common food allergy[19]. It generally develops in childhood before it disappears again during school age. Cow’s milk allergy sufferers reply to every dairy products, including cheese, yoghurt, butter and cream, and 92 percent are also allergic to goat’s milk[20]. People with cow’s milk reactions should also avoid goat and sheep’s milk products[21].

Important: An allergy to cow’s milk is a completely diverse disease than lactose intolerance.

Wheat allergy

Wheat allergy most commonly develops in childhood and generally resolves itself before adulthood[8].

20 percent of wheat allergic individuals show cross-reactions with other cereals such as spelt or rye[20]. But you should not extend your suspicions to every cereals, as this would restrict your diet too much. If in doubt, it is better to do an allergy test. It’s best to make certain of what you can tolerate using a provocation test.

Important: A wheat allergy is not coeliac disease! As a wheat allergic individual you can still eat gluten-containing foods as endless as they do not contain wheat.

Chicken egg allergy

Chicken egg allergy is the second most common food allergy in childhood after cow’s milk allergy.

It too often resolves itself in adulthood[6].

And this is excellent to know: Some foods own a reduced potential to cause allergies when they are cooked. For example, numerous people with allergies can much better tolerate strongly heated milk or eggs used for baking. Peanuts, on the other hand, own an even higher allergic potential when roasted[22-24].

Cross allergies

It is not the entire foodstuff that triggers an allergic reaction, but much rather certain proteins within them that act as allergens.

Sometimes diverse types of these proteins are so similar that the body can not tell them apart. In such a case, a cross-reaction may occur: The body is sensitised towards one allergen, but also reacts to the other. This happens between foods — and those allergic to peaches often also react to apples. However, it can also happen that a pollen allergy leads to a cross-reaction with fruits, vegetables and nuts. And even latex often triggers cross-allergies — against kiwis, bananas and avocados.

Foods and their potential cross allergies[6]:

Allergic to

Cross reaction to

Risk of cross-allergies

Cow’s milk

Goat’s milk

92 percent

Cantaloupe melons

Watermelons, bananas, avocados

92 percent

Shrimps

Crabs, lobster

75 percent

Peaches

Apples, plums, cherries, pears

55 percent

Pollen

Apples, peaches, honey melons

55 percent

Salmon

Swordfish, sole

50 percent

Walnuts

Brazil nuts, cashews, hazelnuts

37 percent

Latex

Kiwis, bananas, avocados

35 percent

Wheat

Barley, rye

20 percent


What is a food allergy?

When you own an allergy, your immune system reacts strongly to an otherwise harmless substance.

The substances which can trigger allergies are known as allergens. These are diverse proteins may happen in pollen, animal hair, the faeces of dust mites or even in food.

What happens with an allergy in the body?

An allergy always starts with a sensitisation towards an allergen. This means that the body will produce certain IgE antibodies in an excessive quantity. Each of these immunoglobulins (the «»Ig»») specialises in keeping specific intruders out of the body. In doing so the immune system will combat bacteria, viruses, worms, but unfortunately also harmless allergens.

IgE antibodies bind to receptors on mast cells, which are cells of the immune system.

Laboratories can detect the increased number of IgE antibodies in the blood and assign these to their corresponding allergens – and this is how an allergy test by blood sampling works. If the allergen comes into contact again, the allergen will bind to the IgE antibodies and cause the mast cell to release messenger substances such as histamine. Histamine then promotes inflammation and in so doing triggers the diverse symptoms of an allergy. If in addition to sensitisation symptoms happen, we speak then of an allergy[3, 4].

What types of food allergies are there?

Experts distinguish between diverse types of allergy.

The most common forms of allergy are those of the immediate type, namely type I allergies, which also includes food allergies. The reaction occurs directly after you own consumed the allergen. A person allergic to peanuts then feels symptoms such as a furry tongue and rash between a few seconds and 20 minutes after eating[5]. Delayed immediate reactions are also possible in which another allergic reaction can happen after four to six hours.

And this is excellent to know: some food allergies can resolve themselves by themselves during adulthood. For example, milk, egg, soy and wheat allergies generally affect children but then vanish in 90 percent of cases.

Allergies to nuts, fish and shellfish, however, are generally retained for entire lives[8].


History

The hygiene hypothesis was first introduced in the tardy 1980s by David P. Strachan, a professor of epidemiology, in the British Medical Journal. Strachan found that children in larger households had fewer instances of hay fever because they are exposed to germs by older siblings. This finding led to further research that suggests a lack of early childhood exposure to less than pristine conditions can increase the individual’s susceptibility to disease.

For example, in the tardy 1990s, Dr.

Erika von Mutius, a health researcher, compared the rates of allergies and asthma in East Germany and West Germany, which unified in 1999. Her initial hypothesis was that East German children, who grew up in dirtier and generally less healthful conditions, would own more allergies and suffer more from asthma than their Western counterparts. However, her research found the opposite: children in the polluted areas of East Germany had lower allergic reactions and fewer cases of asthma than children in West Germany.

Further research has found that children in developing areas of the world are less likely to develop allergies and asthma compared with children in the developed world.


Food allergy — symptoms

A variety of symptoms may indicate the presence of an allergy or intolerance.

Some are mild and barely noticeable, while some cannot be overlooked and others are even extremely severe, such as allergic shock. Food allergies do not always just affect the mouth and the gastrointestinal tract, since they can also impact on the skin and the respiratory tract[2, 5].

In the extreme case: allergic shock

The most severe form of allergic reaction is allergic shock, which is also referred to as anaphylactic shock. The causes of this are generally insecticides, medicines and, especially in children, food. But foods such as nuts, soya, shellfish, milk and eggs can also cause anaphylaxis.

In anaphylactic shock, large amounts of histamine are released, resulting in severe dilation of the blood vessels.

The blood pressure falls rapidly, while dizziness, fainting and even death can happen in the worst case.

If you are aware of the risk of shock, you should reply quickly if more severe allergic symptoms happen and call the emergency services immediately. While waiting for the ambulance arrives, the victim should be placed in the shock position, i.e. lying below with the legs up. At-risk patients also often carry an emergency kit containing an adrenaline pen.

This emergency medicine will ensure that the shock abates[3, 4].

And this is excellent to know: Depending on the severity of an allergy, even the smallest amounts of an allergen sometimes suffice to trigger an anaphylactic shock — such as the remains of a nut on the partner’s lips or traces of soy in certain foods[3, 4].

What are the symptoms of food allergies?

In allergic reactions, the following symptoms frequently occur:

  1. Burning in the oral cavity, swelling of the mucous membranes and tongue
  2. Breathlessness extending to allergic asthma
  3. Diarrhoea, vomiting and abdominal pain
  4. Redness and wheals on the skin (nettle fever)
  5. A drop in blood pressure

Allergy-enhancing factors

Just because you own an allergy, you will not automatically reply to the slightest sign of the allergen.

A reaction threshold exists, meaning that you need exposure to a certain quantity of the allergen before symptoms happen. As an example, peanut allergy sufferers often own a extremely low reaction threshold, with a little crumb of a peanut being enough to cause a furry tongue and swollen neck.

Stress, sports and infections can also lower your reaction threshold. This will make it more likely that you suffer an allergic reaction.

During or immediately after exercise, the risk of an allergic reaction is increased. This phenomenon even has a name: namely exercise-induced anaphylaxis (EIA).

If you eat a food that you are allergic to correct before exercise, you may experience hives and itching, or feel drowsy. You should avoid any of your food allergens at least four to five hours before each workout[32].

Studies own shown that stress can make the symptoms of allergy worse and more likely to happen. If you suffer from an allergy and are often stressed out, it makes sense to deliberately seek to be relaxed. Relaxation techniques such as yoga, autogenic training and progressive muscular relaxation can every help.

Infections can also potentiate allergies. Elevated temperatures lead to increased blood circulation, which in turn can cause more allergen to enter the bloodstream.

With infections in the gastrointestinal tract, allergies are aggravated by the fact that a larger quantity of undigested proteins crosses the mucous membrane. As a result, such proteins affect the sensitised immune system and are more likely to trigger an allergic reaction[34].

Alcohol is also discussed as an allergy-enhancing factor among scientists. In some case studies, allergy symptoms were exacerbated under the influence of alcohol, and in alcoholics the number of IgE antibodies is increased.

Conclusive scientific evidence for this association, however, does not yet exist[34].


A balance

The conflict between cleanliness and exposure can leave parents feeling confused. There are numerous microbes that can make children extremely ill, such as such as respiratory syncytial virus (RSV), E.coli and salmonella. So cleaning the home is still extremely significant. What should children be exposed to and what should they be protected from?

The CDC recommends regularly cleaning and disinfecting surfaces in the home, especially when surfaces own been contaminated by fecal matter or meat or own come in contact with those who own a virus.

Children are also encouraged, though, to frolic exterior, even if they may get dirty in the process. This balancing act may prove to assist children stay healthy while still developing a healthy immune system.

Sonpal thinks that the healthy growth of the immune system isn’t just about coming in contact with dirt. It also has to do with what foods are consumed, what helpful of environments the person grows up in and intrinsic genetics coupled with physical activity levels. Harvard Medical School noted that getting plenty of sleep, avoiding cigarette smoke, drinking in moderation and controlling blood pressure also every frolic a part in a healthy immune system.

Additional Resources

1Department of Health, Human Performance and Recreation, Baylor University, Waco, Texas, USA

*Corresponding Author:Christie Maria Sayes, Environmental Science Department, Baylor University, One Bear Put 97266, Waco, TX 76798-7266;

Food allergy, Food sensitivity, Food intolerance, Environment, 10 Essential services

Human health outcomes

The long-term human health outcomes that could happen from food allergies include increased allergic reactions (to more than one allergen), chronic psychological effects, and decreased life expectancy.

It is common among people with one food allergy to develop additional allergies and those allergens result in an anaphylactic reaction [1, 4, 53]. For some food allergies, children own a high probability of outgrowing the allergic reaction by the time they grow to adulthood; however, a peanut or tree nut allergy, which own the highest rates of anaphylaxis, are rarely outgrown [2, 27, 54].

What is the hygiene hypothesis and what does it own to do with food allergies

Food allergies can also affect quality of life and can even cause psychological distress [55-58]. Food allergies developed in adulthood can cause a significant adjustment, which has shown to be hard for people. If a person has several food allergies, as well as asthma, s/he develop aversions to food, lack in socialization, and difficulty breathing [19, 59, 60]. Specifically, eliminating certain foods in the diet results in missing nutrients. Although rare, death can happen as a result of an allergic reaction [61]. This generally occurs in people who own anaphylactic reactions if treatment is not timely or if the reaction is not noticed.

Public health policies from the 10 essential public health services provide a suitable framework to develop best practices for individuals, healthcare practitioners, charities, recreation organizations, schools, and community services to follow. Public health systems (i.e. the network of every public, private, and voluntary entities in a community) deliver essential public health services. Briefly, the 10 essential services include monitoring health, diagnosing problems and identifying hazards, informing people, mobilizing partnerships, developing policies, enforcing regulations, linking people to services, assuring competencies in workforce, evaluating effectiveness, and researching innovative solutions [62].

Essential Service

Interface with Food Allergies and the Environment

1
Monitor Health

• Be aware of common allergies and incidence rates
• Assess the health status of their individuals

2
Diagnose and Investigate

• Identify and investigate health threats in a timely manner
• Create action plan to address emerging health related threats

3
Inform, Educate, Empower

• Prevent health emergencies through education
• Inform school communities through the use of signage

4
Mobilize Community Partnerships

• Establish relationships between the school, the community, the parents, and the local physicians
• Ensure roles and responsibilities in case of an emergency
• Form a local coalition to promote allergy friendly food establishments, schools, and other public places

5
Develop Policies

• Ban certain allergens from the location
• Protect the health of the most vulnerable populations

6
Enforce Laws

• Utilize and enforce food allergy regulations
• Provide alternative allergen-friendly food options

7
Link to Care

• Provide constant management and surveillance
• Hire practitioners who can diagnose and treat those with food allergies
• Provide safe spaces in schools for children with food allergies to go
• Provide grocery stores with allergy friendly food
• Provide allergy friendly and safe food establishments
• Ensure resources provided are affordable and available to every people regardless of race and/or culture

8
Guarantee Capable Workforce

• Employ practitioners that up to date on the most current research in the field of food allergies
• Educate healthcare workers, teachers, and food service handlers

9
Evaluate

• Ensure that the policies, professionals, and regulations in put are working
• Assess efficacy of policies
• Improve upon deficiencies

10
Research

• Continue to conduct research in the field of food allergies
• Engage efforts for diagnosis, treatment, and cures
• Seek prevention strategies and analyze costs versus benefits

Table 3: The 10 essential services as they relate to food allergy occurrences.
Table 3 lists the 10 essential services and explains how each relates to food allergy occurrences.

Currently, the following components provide athletic services towards addressing the food allergy epidemic, as it relates to environmental factors, in the United States:

  • Regulations are enforced.

    What is the hygiene hypothesis and what does it own to do with food allergies

    Alternative allergen-friendly food options are available.

  • Workforce is capable. Continuing educations is available for practitioners, healthcare workers, teachers, and food service handlers.
  • Policies are developed. Certain allergens are banned from specific locations and the most vulnerable populations are protected.
  • Health is monitored. Healthcare practitioners are aware of common allergies and incidence rates in localities and assess the health status of individuals.
  • Link to Healthcare is known. Practitioners who can diagnose and treat those with food allergies are trained, hired, and supplied with resources.
  • Community partnerships are mobilized.

    Relationships between schools, the community centers, affected individuals (or parents of individuals), food establishments, and local physicians are established and the roles and responsibilities of each stakeholder are defined.

  • The system is evaluated. Policies and regulations are in put and working.

Conversely, a few challenges and data gaps in the field of environmental factors and their contribution to the food allergy epidemic still exist. The following components of the 10 essential services currently provide insufficient resources towards addressing the food allergy epidemic, as it relates to environmental factors, in the United States:

Conversely, a few challenges and data gaps in the field of environmental factors and their contribution to the food allergy epidemic still exist.

The following components of the 10 essential services currently provide insufficient resources towards addressing the food allergy epidemic, as it relates to environmental factors, in the United States:

  • Prevention: There is a lack of information (i.e. protocols, guidance documents, or educational material) available for individuals to prevent exacerbation of existing allergies or development of new allergies.
  • Research: Several studies contain contradicting information. Ethnicity plays a role in the risk of some individuals developing a food allergy; however, the conclusions are not uniform across every studies and no trends own been founds. Because of this, it is increasingly hard to establish causation for food allergy development.
  • Diagnosis: Due to the increased prevalence of individuals self-diagnosing, precise incidence rates are outdated and lack correlations with environmental health, urbanization, food system and accessibility, geography, socioeconomic, or other demographic data.

Recent research efforts own found more success in correlating environment factors and food allergies when more than one variable, such as environmental health, urbanization, food system and accessibility, geography, socioeconomic, or other demographic data.

Dempfle et al. [63] suggests that by looking at both genetic and environmental factors together, more conclusive results can be obtained [63]. Simpson et al hypothesizes that precision medicine (a.k.a. personalized medications) is a possible intervention for food and seasonal allergies [9]. Through the use of precision medication, allergens can be directly targeted and unintended drug-induced side effects may be prevented.

The five working hypotheses postulating the sources of food allergies deserve further investigations and possible interventions.

In any intervention regarding food allergies, starting young and early exposure is key. Any of the possible interventions such as dermal or oral introduction are most affective if done early on in life. Recommendations for further research include identifying potential combinations of gene, introducing food exposure in early life stage and through a variety of exposure routes, and developing frameworks for designing precision medicines.

Competing Financial Interests Declaration

Neither ENB nor CMS own any conflicts of interest, financial or otherwise.

The food allergy hypotheses

Through the review of the scientific literature, several hypotheses were presented, tested, and either proven true or inconclusive.

These hypotheses purpose to explain some of possible reasons behind the current allergy epidemic and offer recommendations to prevent allergies from developing in otherwise healthy individuals. These five (5) hypotheses include:

Recent research efforts own found more success in correlating environment factors and food allergies when more than one variable, such as environmental health, urbanization, food system and accessibility, geography, socioeconomic, or other demographic data. Dempfle et al. [63] suggests that by looking at both genetic and environmental factors together, more conclusive results can be obtained [63].

What is the hygiene hypothesis and what does it own to do with food allergies

Simpson et al hypothesizes that precision medicine (a.k.a. personalized medications) is a possible intervention for food and seasonal allergies [9]. Through the use of precision medication, allergens can be directly targeted and unintended drug-induced side effects may be prevented.

The five working hypotheses postulating the sources of food allergies deserve further investigations and possible interventions. In any intervention regarding food allergies, starting young and early exposure is key. Any of the possible interventions such as dermal or oral introduction are most affective if done early on in life. Recommendations for further research include identifying potential combinations of gene, introducing food exposure in early life stage and through a variety of exposure routes, and developing frameworks for designing precision medicines.

Competing Financial Interests Declaration

Neither ENB nor CMS own any conflicts of interest, financial or otherwise.

The food allergy hypotheses

Through the review of the scientific literature, several hypotheses were presented, tested, and either proven true or inconclusive.

These hypotheses purpose to explain some of possible reasons behind the current allergy epidemic and offer recommendations to prevent allergies from developing in otherwise healthy individuals. These five (5) hypotheses include:

  • Vitamin D exposure hypothesis
  • Hygiene hypothesis
  • Antioxidant production hypothesis
  • Dietary fat intake hypothesis
  • Dual-allergen exposure hypothesis

5.1 Dietary fat intake hypothesis (H1): The dietary fat intake hypothesis offers the thought that reduction in consumption of animal fats and increase in margarine and vegetable oils use has led to the decrease in common food allergies [4, 36].

Individuals use margarine and vegetable oil in their diets in an increasing rate due to the conception that these oils are a healthier alternative to animal fats. Some literature presents a possible correlation in a decrease in animal fats and a positive correlation with an increase in food allergies [4]. Through literature search, 114 papers were found to pertain to this hypothesis (Figure 3).

5.2 Antioxidant production hypothesis (H2): The antioxidant hypothesis argues that the decrease in consumption of unused fruit and vegetables accounts for food allergies and the adverse outcome of asthma [4, 37].

Fruits and vegetables contain vital nutrients and antioxidants. These nutrients and antioxidants frolic significant roles in maintaining health and fighting infection. With decreased fruit and vegetable intake, individuals do not get necessary essential elements needed for building sufficient immune system. Through a search of the literature, 462 articles included the antioxidant hypothesis (Figure 3).

5.3 Vitamin D exposure hypothesis (H3): The vitamin D hypothesis has been postulated in two diverse (i.e. opposing) forms. The first form argues that increases of vitamin D levels own led to increased food allergies; while the second form argues that decreases of vitamin D levels own led to increased food allergies [4, 38].

The first form argues that because of an increased consumption of Vitamin D from sources such as dairy products, more children experience an increase in food allergies [39]. The second form presents the thought that a lack of Vitamin D, mainly in the form of sunlight, leads to an increased risk of food allergies [40]. Several studies own been conducted comparing epinephrine injection (a.k.a. EpiPen®) usage rates in northern United States to southern United States [41-44]. States in the northern region had higher rates of food allergies as well as less exposure to sunlight. The Vitamin D exposure hypothesis has been frequently evaluated.

A literature search revealed 80 papers on the topic (Figure 3).

5.4 Hygiene hypothesis (H4): Studies testing the hygiene hypothesis own rarely focused on food allergies, as the adverse outcome, alone. However, the hypothesis examines the role of commensal gut flora in the development of food allergies [4, 45, 46]. Studies focused on the effects of protecting children from microorganism exposure and the chances of food allergy development [47].

Exposing children to microorganisms has been shown to strengthen the immune system [48, 49]. The hygiene hypothesis is the most commonly studied food allergy hypothesis. A review of the literature presented 232 papers on the topic (Figure 3). This also was the most researched hypothesis through clinical experiments presenting with quantitative findings.

5.5 Dual-allergen exposure hypothesis (H5): The final food allergy hypothesis involves dual- allergen exposure and argues that if a food allergy only occurs if the allergen is presented to an individual [4, 50, 51].

More specifically, if a certain food is not exposed to a culture or community, there should be no risk of developing an allergy to that food item. This was evident in Northern Europe in the 1980’s [52]. The dual-allergen exposure hypothesis is the least researched hypothesis. A literature search presented only 10 papers on the topic (Figure 3). The papers that were found every consisted of review articles.

This hypothesis has a lot of room for growth and research.

Methods

We performed a structured literature search focused on identifying every relevant human studies related to environmental factors and food allergies. Multiple databases were queried between November 2016 and May 2017. PubMed, Scopus, and Web of Science search engines were utilized with keyword searches. Papers were included if they were tagged with at least one search term from Group A and the term “environment*” from Group term B (Table 1). Further literature research narrowed the field to pediatric relevance. The most common themes identified from the original Group B term included: environmental factors, farm environment, smoking, and air pollution.

Resultant papers written in English, found in the keyword search, and peer-reviewed were included in the analysis. Searches included both research and review articles on humans, but excluded articles using animal or cell-based models. Other inclusion criteria include specific environmental factors noted in abstract and cohorts of children or young adults.

Databases

Group A terms

Group B terms

Number of papers returned

PubMed

food allergy

environment*

212

food sensitivity

1

food intolerance

9

Scopus

food allergy

environment*

569

food sensitivity

4

food intolerance

23

Web of Science

food allergy

environment*

247

food sensitivity

1

food intolerance

10

Table 1: Search terms for literature review.

*indicates end-truncated search term. Terms entered into database with quotation marks returned results with exact matches. Data includes both research and review articles.

Acknowledgments

The authors thank Baylor University for financial support.

Introduction

Approximately 50 million Americans experience a food allergy. Food allergies affect up to six percent (6%) of children and four percent (4%) of adults (ACAAI 2016).

Food allergies can develop at any age, but typically appear first during infancy or childhood (ACAAI 2016). However, in some occasions, an individual can develop an allergy, and subsequent adverse effect, to a food they own previously eaten with no negative symptoms (ACAAI 2016). In a
recent study released by the Middle for Disease Control (2013), it was reported that between the years of 1997 and 2011, food allergies among children increased 50% (CDC 2013). The number of food allergies is increasing, but the cause is unknown. The rate of anaphylaxis reactions after exposure to food is increasing, as well [1]. Anaphylactic reactions can be deadly if not immediately treated; key signs are facial swelling and difficulty breathing cause is unknown [1].

Little data is available that postulates the causes of food allergies.

However, some hypotheses own emerged over the past 10 years. For instance, factors such as race, ethnicity, and genetics contribute to allergy development (ACAAI 2016). More recently, research efforts own shifted from genetic-centric to synergistic reasoning incorporating environmental factors. Another striking statistic emerging in the literature over the past 5 years is the overwhelmingly high rates of food allergy development among individuals residing in first world countries, as compared to individuals who live in third world countries [2].

It has been postulated that the highly variable environmental factors in an industrialized nation contributes to the increase in the onset of food allergy [3].

Food allergy conditions are a complicated diagnosis; each individual is affected differently. It is also a hard area of epidemiological, toxicological, or medicinal research because numerous food allergies are self-reported without qualifying or quantifying metrics (such as pathology, symptom, or biomarker identification). To complicate the subject further, a food allergy can exist along a continuum (or spectrum).

Figure 1 describes the spectrum of food disorder; an Individual can own ‘no sensitivity’, food ‘sensitivity’, and/or a food ‘allergy’ to a food product. A food allergy is generally regarded as the more severe diseased state and induces an exaggerated immune response. Lastly, the allergic reaction to a food can vary among inflicted individuals. Example conditions arising from a food allergy could range from itching skin to urticarial outbreak to gastrointestinal dysfunction to anaphylaxis (CDC 2013).

Literature presents the possible correlation between the environment and an increase in allergies.

While no literature has yet to prove causation, a few articles own proposed possible correlations. Within the environmental construct of food and food delivery, the individual’s culture often promotes specific allergic reactions; if a food is not eaten in the population, then tolerance to the food is never developed, thus can result in a food allergy. A few significant research studies published in the literature own postulated that environmental factors influence the onset of food allergies, but extremely few own collected empirical data suggesting causation.

Without causations and known ways to prevent food allergies, the epidemic will continue to grow and continue to adversely affect millions of people. A country’s food system can present itself as a cause to an allergen being present in the country or not. The dual-allergen-exposure hypothesis hypothesizes that in countries where a food is not consumed, there is no environmental exposure, an allergy to that food will not happen [4].

An example of this occurred in the United Kingdom. Prior to 1970, kiwis had never been present or eaten in the UK. Since the 1970’s when the kiwi was introduced to the UK, the rate of kiwi allergies has grown significantly [4].

Another possible hypothesis could be in countries where they avoid a certain food i.e. peanuts, the rates of peanut allergies tend to be higher. There’s a misunderstanding that by completely avoiding and not introducing an infant/child to the item, they won’t develop an allergy. However, we’ve seen in America that this proves the opposite. Consequently, countries such as in Africa and some Asian countries where peanuts are widely eaten and avoided, there are extremely low rates of peanut allergies [4].

Researchers know that the environment plays a role in the development of food allergies, but few own studies own found concrete evidence to support the role that the environment plays. Some possible roles the environment contributes to food allergies include: traffic pollution, animal exposure, farm environment, smoking, and air pollution. One study reviewed found that long-term exposure to traffic pollutions can increase allergy sensitization [3]. The study looked at children. One possibility of this correlation could be the knowledge that exposure to traffic and air pollution can increase rates of asthma which therefore can increase the rates of food allergies.

Another study looked at the effects of dog ownership on the development of atopy among infants. It found that households that had a dog, the infants residing in these houses, were less likely to develop atopic dermatitis. This could appear in the form of eczema. It found that these results only proved true with dogs though, cats were evaluated as well but found to own no effect on the development of atopy [5].

Two studies indicated evidence that early exposure to a farm environment could lower the risk of a kid developing atopy in the future. One study found that living on a farm in the early years helped to lift rates of genotype CD14. Low CD14 levels are associated with an increased risk of developing atopic sensitization.

This study showed that the farm environment contributed to higher rates of CD14 among infants therefore, the infants had a lower risk of developing atopy [6]. Another study on farm environment found that a farm environment was successful in preventing allergic rhinitis (hay fever) and allergic conjunctivitis (itching eyes), but not allergic dermatitis (eczema) [7]. Allergic rhinitis and allergic conjunctivitis do not lead to the development of food allergies. More research needs to be done on the protective factors of a farm environment and the development of food allergies.

Air pollution can be another cause of developing food allergies.

A study found that passive or athletic smoking could frolic a role in the sensitization to food allergens. Passive smoking is inhalation of second-hand smoke and athletic smoking is a person who smokes. The same study found that exposure to aeroallergens or air pollutants can cause higher rates of respiratory infections which in turn might frolic an significant role in the sensitization to food allergens as well [8].

The purpose of this review is to examine environmental factors as a cause of food allergies.

First, we attempted to identify environmental factors that contribute to the increasing prevalence of food allergies in the past two decades. Second, we summarized the role that physiological factors (such as genetics, gender, and age) own played in the development of food allergies. Third, we evaluated the importance of the 10 Essential Services of Public Health in food allergy causation. The objective of this paper is to define the role of the environment as it relates to food allergies.

If environmental factors contribute to the onset of food allergies, then this epidemic could be labeled as an emerging public health issue.

Discussion

4.1 Individual allergens, their prevalence and diagnoses

A relatively little quantity of foods are referred to as major food allergens, i.e. foods known to elucidate an allergic reaction in humans. These foods include milk, egg, tree nuts, peanuts, seafood, shellfish, soy, and wheat [16]. People can exhibit intolerance to other foods, such as lactose or sulfites; but the adverse reaction to humans after exposure is not described as life threatening.

Nut allergies (peanut and tree nut) are the leading cause of anaphylaxis, either fatal or nonfatal, in the United States and the United Kingdom [16].

Unlike other food allergens, peanuts are linked to a genetic susceptibility. The environmental and physiological precursors to the development of a peanut allergy include early onset of a soy allergy and eczema as an baby, respectfully [17]. In some studies, maternal diet plays a role in the development of a peanut allergy, but other studies own proven this relation untrue [17]. A peanut allergy is unique in that the reaction is chronic and sustained throughout an individual’s life [17].

According to several studies, the prevalence of food allergies are significantly lower in developing countries than those in developed countries [18].

However, individuals from developing countries who immigrate to modernized countries lose their protection to certain allergens [18]. The difference between the rates of food allergy onset between developed versus developing countries could be due to factors in the local environmental construct.

It is hard to pinpoint the rates of allergy prevalence due to the common practice of self- diagnosis, rather than practitioner diagnosis. Allergies can range from a less complicated intolerance or sensitivity to more complicated anaphylaxis.

Few studies own been capable to accurately report the prevalence of certain food allergens [19]; and precise diagnosis is directly related to prevalence. The most widely accepted method to qualitatively diagnose an allergy is through either a skin test or blood test. Skin allergy testing is a method for medical diagnosis of allergies designed to inflame a controlled irritation response [20]. Blood allergy tests measure the upregulation of immunoglobulin E (IgE, the antibody that triggers food allergy symptoms) to specific foods [21].

In an ideal setting, the test would also include a double-blind, placebo-controlled food challenge (DBPCFC) [22]. More precise prevalence rates for food allergies can be gained with more DBPCFC reported studies.

4.2 Commonality among children

The onset of food allergies diagnosed among children in the United States own risen 50% since 1997 [23]. Not only own the rates of allergies increased in the past two decades, but the rates of morbidity associated with allergies own risen, as well. Jackson et al.

[23] concludes that there is no clear understanding of the reasons for the rising incidence rates; however, the nature of the interaction between genetic and environmental factors requires more research [23].

4.3 Allergy vs. Sensitivity

Any allergy has the potential to triggers a life threatening immune response. A sensitivity (also referred to as an intolerance) is generally not life threatening, but does result from the inability to metabolize or digest a food completely [22, 25].

The majority of studies that focus on food allergies tend to avoid the more mild and less complicated food intolerances or sensitivities [26]. There evidence to propose, however, that some food sensitivities can lead to food allergies over time [27] (Figure 2). Most food intolerances and sensitivities are associated with abdominal symptoms such as nausea, bloating, and pain [28]. However, they can also be associated with symptoms such as neurological dysfunction, psychological disturbances, fibromyalgia, and skin rash [29].

Although there are currently no proven methods to overcome a diagnosed food allergy, there are known ways to overcome a sensitivity related food illness. The first step includes completely eliminating the food from the diet, avoidance of the trigger response.

The second step includes biochemical restoration. This is the body repairing itself since it is no longer experiencing illness. The third and final step is elimination of bioaccumulated toxicant load. Since the body is no longer experiencing the food item, it is capable to finish rid itself of the toxicants. In some cases, the food at this point can start to be reintroduced to the diet in little amounts.

The most common food sensitivities include complicated carbohydrates, histamines, and lactase. In carbohydrate intolerance, an essential enzyme is missing from the digestion processes, which causes the incomplete metabolism of fermentable carbohydrates (i.e.

sugars and starches). In histamine intolerance, foods with large quantity of the chemical histamine (i.e. alcohol, bananas, avocados, or eggplants) cause itchy eyes or tongue, runny nose, or congestion due to a lack of the enzyme diamine oxidase (DAO). In lactose intolerance, the enzyme lactase, responsible for breaking below lactose or milk sugar, is missing and causes diarrhea, nausea, vomiting, abdominal cramps, and bloating [25].

4.4 Known causes and pre-existing health conditions

There is limited information on the known causes of food allergies. There own been numerous correlations found but only a few studies own proven causation.

Asthma and eczema are known pre-existing health conditions that often lead to the development of food allergies [30, 31]. Generally accepted correlations are listed below:

5.1 Dietary fat intake hypothesis (H1): The dietary fat intake hypothesis offers the thought that reduction in consumption of animal fats and increase in margarine and vegetable oils use has led to the decrease in common food allergies [4, 36].

Individuals use margarine and vegetable oil in their diets in an increasing rate due to the conception that these oils are a healthier alternative to animal fats. Some literature presents a possible correlation in a decrease in animal fats and a positive correlation with an increase in food allergies [4]. Through literature search, 114 papers were found to pertain to this hypothesis (Figure 3).

5.2 Antioxidant production hypothesis (H2): The antioxidant hypothesis argues that the decrease in consumption of unused fruit and vegetables accounts for food allergies and the adverse outcome of asthma [4, 37].

Fruits and vegetables contain vital nutrients and antioxidants. These nutrients and antioxidants frolic significant roles in maintaining health and fighting infection. With decreased fruit and vegetable intake, individuals do not get necessary essential elements needed for building sufficient immune system. Through a search of the literature, 462 articles included the antioxidant hypothesis (Figure 3).

5.3 Vitamin D exposure hypothesis (H3): The vitamin D hypothesis has been postulated in two diverse (i.e.

opposing) forms. The first form argues that increases of vitamin D levels own led to increased food allergies; while the second form argues that decreases of vitamin D levels own led to increased food allergies [4, 38]. The first form argues that because of an increased consumption of Vitamin D from sources such as dairy products, more children experience an increase in food allergies [39]. The second form presents the thought that a lack of Vitamin D, mainly in the form of sunlight, leads to an increased risk of food allergies [40].

Several studies own been conducted comparing epinephrine injection (a.k.a. EpiPen®) usage rates in northern United States to southern United States [41-44]. States in the northern region had higher rates of food allergies as well as less exposure to sunlight. The Vitamin D exposure hypothesis has been frequently evaluated. A literature search revealed 80 papers on the topic (Figure 3).

5.4 Hygiene hypothesis (H4): Studies testing the hygiene hypothesis own rarely focused on food allergies, as the adverse outcome, alone.

However, the hypothesis examines the role of commensal gut flora in the development of food allergies [4, 45, 46]. Studies focused on the effects of protecting children from microorganism exposure and the chances of food allergy development [47]. Exposing children to microorganisms has been shown to strengthen the immune system [48, 49]. The hygiene hypothesis is the most commonly studied food allergy hypothesis. A review of the literature presented 232 papers on the topic (Figure 3). This also was the most researched hypothesis through clinical experiments presenting with quantitative findings.

5.5 Dual-allergen exposure hypothesis (H5): The final food allergy hypothesis involves dual- allergen exposure and argues that if a food allergy only occurs if the allergen is presented to an individual [4, 50, 51]. More specifically, if a certain food is not exposed to a culture or community, there should be no risk of developing an allergy to that food item. This was evident in Northern Europe in the 1980’s [52]. The dual-allergen exposure hypothesis is the least researched hypothesis. A literature search presented only 10 papers on the topic (Figure 3).

The papers that were found every consisted of review articles. This hypothesis has a lot of room for growth and research.

Methods

We performed a structured literature search focused on identifying every relevant human studies related to environmental factors and food allergies. Multiple databases were queried between November 2016 and May 2017. PubMed, Scopus, and Web of Science search engines were utilized with keyword searches. Papers were included if they were tagged with at least one search term from Group A and the term “environment*” from Group term B (Table 1).

Further literature research narrowed the field to pediatric relevance. The most common themes identified from the original Group B term included: environmental factors, farm environment, smoking, and air pollution. Resultant papers written in English, found in the keyword search, and peer-reviewed were included in the analysis. Searches included both research and review articles on humans, but excluded articles using animal or cell-based models. Other inclusion criteria include specific environmental factors noted in abstract and cohorts of children or young adults.

Databases

Group A terms

Group B terms

Number of papers returned

PubMed

food allergy

environment*

212

food sensitivity

1

food intolerance

9

Scopus

food allergy

environment*

569

food sensitivity

4

food intolerance

23

Web of Science

food allergy

environment*

247

food sensitivity

1

food intolerance

10

Table 1: Search terms for literature review.

*indicates end-truncated search term. Terms entered into database with quotation marks returned results with exact matches. Data includes both research and review articles.

Acknowledgments

The authors thank Baylor University for financial support.

Introduction

Approximately 50 million Americans experience a food allergy. Food allergies affect up to six percent (6%) of children and four percent (4%) of adults (ACAAI 2016). Food allergies can develop at any age, but typically appear first during infancy or childhood (ACAAI 2016). However, in some occasions, an individual can develop an allergy, and subsequent adverse effect, to a food they own previously eaten with no negative symptoms (ACAAI 2016).

In a
recent study released by the Middle for Disease Control (2013), it was reported that between the years of 1997 and 2011, food allergies among children increased 50% (CDC 2013). The number of food allergies is increasing, but the cause is unknown. The rate of anaphylaxis reactions after exposure to food is increasing, as well [1]. Anaphylactic reactions can be deadly if not immediately treated; key signs are facial swelling and difficulty breathing cause is unknown [1].

Little data is available that postulates the causes of food allergies.

However, some hypotheses own emerged over the past 10 years. For instance, factors such as race, ethnicity, and genetics contribute to allergy development (ACAAI 2016). More recently, research efforts own shifted from genetic-centric to synergistic reasoning incorporating environmental factors. Another striking statistic emerging in the literature over the past 5 years is the overwhelmingly high rates of food allergy development among individuals residing in first world countries, as compared to individuals who live in third world countries [2]. It has been postulated that the highly variable environmental factors in an industrialized nation contributes to the increase in the onset of food allergy [3].

Food allergy conditions are a complicated diagnosis; each individual is affected differently.

It is also a hard area of epidemiological, toxicological, or medicinal research because numerous food allergies are self-reported without qualifying or quantifying metrics (such as pathology, symptom, or biomarker identification). To complicate the subject further, a food allergy can exist along a continuum (or spectrum). Figure 1 describes the spectrum of food disorder; an Individual can own ‘no sensitivity’, food ‘sensitivity’, and/or a food ‘allergy’ to a food product. A food allergy is generally regarded as the more severe diseased state and induces an exaggerated immune response.

Lastly, the allergic reaction to a food can vary among inflicted individuals. Example conditions arising from a food allergy could range from itching skin to urticarial outbreak to gastrointestinal dysfunction to anaphylaxis (CDC 2013).

Literature presents the possible correlation between the environment and an increase in allergies. While no literature has yet to prove causation, a few articles own proposed possible correlations. Within the environmental construct of food and food delivery, the individual’s culture often promotes specific allergic reactions; if a food is not eaten in the population, then tolerance to the food is never developed, thus can result in a food allergy.

A few significant research studies published in the literature own postulated that environmental factors influence the onset of food allergies, but extremely few own collected empirical data suggesting causation. Without causations and known ways to prevent food allergies, the epidemic will continue to grow and continue to adversely affect millions of people. A country’s food system can present itself as a cause to an allergen being present in the country or not. The dual-allergen-exposure hypothesis hypothesizes that in countries where a food is not consumed, there is no environmental exposure, an allergy to that food will not happen [4].

An example of this occurred in the United Kingdom. Prior to 1970, kiwis had never been present or eaten in the UK. Since the 1970’s when the kiwi was introduced to the UK, the rate of kiwi allergies has grown significantly [4].

Another possible hypothesis could be in countries where they avoid a certain food i.e. peanuts, the rates of peanut allergies tend to be higher. There’s a misunderstanding that by completely avoiding and not introducing an infant/child to the item, they won’t develop an allergy.

However, we’ve seen in America that this proves the opposite. Consequently, countries such as in Africa and some Asian countries where peanuts are widely eaten and avoided, there are extremely low rates of peanut allergies [4]. Researchers know that the environment plays a role in the development of food allergies, but few own studies own found concrete evidence to support the role that the environment plays. Some possible roles the environment contributes to food allergies include: traffic pollution, animal exposure, farm environment, smoking, and air pollution. One study reviewed found that long-term exposure to traffic pollutions can increase allergy sensitization [3].

The study looked at children. One possibility of this correlation could be the knowledge that exposure to traffic and air pollution can increase rates of asthma which therefore can increase the rates of food allergies. Another study looked at the effects of dog ownership on the development of atopy among infants. It found that households that had a dog, the infants residing in these houses, were less likely to develop atopic dermatitis.

This could appear in the form of eczema. It found that these results only proved true with dogs though, cats were evaluated as well but found to own no effect on the development of atopy [5].

Two studies indicated evidence that early exposure to a farm environment could lower the risk of a kid developing atopy in the future. One study found that living on a farm in the early years helped to lift rates of genotype CD14. Low CD14 levels are associated with an increased risk of developing atopic sensitization. This study showed that the farm environment contributed to higher rates of CD14 among infants therefore, the infants had a lower risk of developing atopy [6]. Another study on farm environment found that a farm environment was successful in preventing allergic rhinitis (hay fever) and allergic conjunctivitis (itching eyes), but not allergic dermatitis (eczema) [7].

Allergic rhinitis and allergic conjunctivitis do not lead to the development of food allergies. More research needs to be done on the protective factors of a farm environment and the development of food allergies.

Air pollution can be another cause of developing food allergies. A study found that passive or athletic smoking could frolic a role in the sensitization to food allergens. Passive smoking is inhalation of second-hand smoke and athletic smoking is a person who smokes.

The same study found that exposure to aeroallergens or air pollutants can cause higher rates of respiratory infections which in turn might frolic an significant role in the sensitization to food allergens as well [8].

The purpose of this review is to examine environmental factors as a cause of food allergies. First, we attempted to identify environmental factors that contribute to the increasing prevalence of food allergies in the past two decades. Second, we summarized the role that physiological factors (such as genetics, gender, and age) own played in the development of food allergies.

Third, we evaluated the importance of the 10 Essential Services of Public Health in food allergy causation. The objective of this paper is to define the role of the environment as it relates to food allergies. If environmental factors contribute to the onset of food allergies, then this epidemic could be labeled as an emerging public health issue.

Discussion

4.1 Individual allergens, their prevalence and diagnoses

A relatively little quantity of foods are referred to as major food allergens, i.e. foods known to elucidate an allergic reaction in humans.

These foods include milk, egg, tree nuts, peanuts, seafood, shellfish, soy, and wheat [16]. People can exhibit intolerance to other foods, such as lactose or sulfites; but the adverse reaction to humans after exposure is not described as life threatening.

Nut allergies (peanut and tree nut) are the leading cause of anaphylaxis, either fatal or nonfatal, in the United States and the United Kingdom [16]. Unlike other food allergens, peanuts are linked to a genetic susceptibility.

The environmental and physiological precursors to the development of a peanut allergy include early onset of a soy allergy and eczema as an baby, respectfully [17]. In some studies, maternal diet plays a role in the development of a peanut allergy, but other studies own proven this relation untrue [17]. A peanut allergy is unique in that the reaction is chronic and sustained throughout an individual’s life [17].

According to several studies, the prevalence of food allergies are significantly lower in developing countries than those in developed countries [18]. However, individuals from developing countries who immigrate to modernized countries lose their protection to certain allergens [18].

The difference between the rates of food allergy onset between developed versus developing countries could be due to factors in the local environmental construct.

It is hard to pinpoint the rates of allergy prevalence due to the common practice of self- diagnosis, rather than practitioner diagnosis. Allergies can range from a less complicated intolerance or sensitivity to more complicated anaphylaxis. Few studies own been capable to accurately report the prevalence of certain food allergens [19]; and precise diagnosis is directly related to prevalence.

What is the hygiene hypothesis and what does it own to do with food allergies

The most widely accepted method to qualitatively diagnose an allergy is through either a skin test or blood test. Skin allergy testing is a method for medical diagnosis of allergies designed to inflame a controlled irritation response [20]. Blood allergy tests measure the upregulation of immunoglobulin E (IgE, the antibody that triggers food allergy symptoms) to specific foods [21]. In an ideal setting, the test would also include a double-blind, placebo-controlled food challenge (DBPCFC) [22].

More precise prevalence rates for food allergies can be gained with more DBPCFC reported studies.

4.2 Commonality among children

The onset of food allergies diagnosed among children in the United States own risen 50% since 1997 [23]. Not only own the rates of allergies increased in the past two decades, but the rates of morbidity associated with allergies own risen, as well. Jackson et al. [23] concludes that there is no clear understanding of the reasons for the rising incidence rates; however, the nature of the interaction between genetic and environmental factors requires more research [23].

4.3 Allergy vs. Sensitivity

Any allergy has the potential to triggers a life threatening immune response.

A sensitivity (also referred to as an intolerance) is generally not life threatening, but does result from the inability to metabolize or digest a food completely [22, 25]. The majority of studies that focus on food allergies tend to avoid the more mild and less complicated food intolerances or sensitivities [26]. There evidence to propose, however, that some food sensitivities can lead to food allergies over time [27] (Figure 2). Most food intolerances and sensitivities are associated with abdominal symptoms such as nausea, bloating, and pain [28].

However, they can also be associated with symptoms such as neurological dysfunction, psychological disturbances, fibromyalgia, and skin rash [29].

Although there are currently no proven methods to overcome a diagnosed food allergy, there are known ways to overcome a sensitivity related food illness. The first step includes completely eliminating the food from the diet, avoidance of the trigger response. The second step includes biochemical restoration. This is the body repairing itself since it is no longer experiencing illness. The third and final step is elimination of bioaccumulated toxicant load. Since the body is no longer experiencing the food item, it is capable to finish rid itself of the toxicants.

In some cases, the food at this point can start to be reintroduced to the diet in little amounts.

The most common food sensitivities include complicated carbohydrates, histamines, and lactase. In carbohydrate intolerance, an essential enzyme is missing from the digestion processes, which causes the incomplete metabolism of fermentable carbohydrates (i.e. sugars and starches). In histamine intolerance, foods with large quantity of the chemical histamine (i.e. alcohol, bananas, avocados, or eggplants) cause itchy eyes or tongue, runny nose, or congestion due to a lack of the enzyme diamine oxidase (DAO). In lactose intolerance, the enzyme lactase, responsible for breaking below lactose or milk sugar, is missing and causes diarrhea, nausea, vomiting, abdominal cramps, and bloating [25].

4.4 Known causes and pre-existing health conditions

There is limited information on the known causes of food allergies.

There own been numerous correlations found but only a few studies own proven causation. Asthma and eczema are known pre-existing health conditions that often lead to the development of food allergies [30, 31]. Generally accepted correlations are listed below:

  • Eczema in infants is an early indicator to the presence of a food allergy [32].
  • Individuals with asthma tend to own a food allergy [16].
  • Children tend to own more than one food allergy present at a time [17].
  • Genetic history of food allergies can increase the risk for developing a food allergy tenfold [16, 21].

A few relationships between environmental factors and food allergies that own been studied but are inconclusive and often debated:

A few relationships between environmental factors and food allergies that own been studied but are inconclusive and often debated:

  • Some foods prepared and eaten raw (uncooked) induce adverse allergic reactions; however, some of the same foods prepared and eaten cooked also induce the same reaction [34].
  • A higher body mass index (BMI) is associated with an increased risk of allergies in children; however, the association varies depending on gender, age, and type of allergen [33].
  • Antibiotic use in children, as well as lack of healthy commensal bacteria has shown to be a risk factor for developing food allergies; but, the trends in observed data are not general [35].

Results

Using this search strategy, we identified a entire of 569 unique articles in English, while carefully eliminating any frequencies in search results among and between the search engines employed.

After other exclusion criteria were accounted for, 11 articles remained for review. The bibliographies of these 11 papers were also examined for additional relevant articles, but relevant cited articles were already captured in the initial analyses. These articles are limited to research studies with experimental designs and are summarized in Table 2. Our analysis is outlined as follows: first, brief overviews of Individual allergens, their prevalence and diagnoses; historical perspectives (Current era vs.

past eras), discussion of Allergy vs. intolerance/sensitivity, and Known causes and pre-existing health conditions are discussed. Second, the five working hypotheses in this field of study are explained. Third, the environmental factors contributing to the onset of food allergies are proposed.

Paper Reference

Brief Study Design

Environmental Factor
Measure

Human Health
Measure

Result

Gern et al. [5]

Pet exposure in the home
compared against
cytokine secretion in infants

Dogs

Indicators of atopy

Having a dog in infancy is
associated with higher
cytokine secretion
profiles and reduced allergic
sensitization

Kilpelainen et al.

[7]

Self-reported wheezing from
Finnish students
(18-24 yr.) collected via
questionnaire

Childhood farm
environment

Food allergy,
allergic
rhinitis and/or
allergic
conjunctivitis

The childhood farm
environment independently
reduced the risk for physician-
diagnosed allergies

Liu et al.

What is the hygiene hypothesis and what does it own to do with food allergies

[8]

Sensitization measured by
skin prick on Chinese
twin pairs (12-28 yr.)

Living conditions,
environment,

and genetics

Peanut and
shellfish food
sensitization

Sensitivity to common food
allergens is influenced
by genetic and
environmental f actors

Leynaert et al. [6]

Questionnaire on farm
exposure in childhood in
2 French centers

Childhood farm
environment &
D14 C-159T
polymorphism

Atopic
sensitization

CD14 C-159T and farm
childhood environment
exposure may
modify the development
of atopy

Simpson et al.

[9]

Population-based birth
cohort study

Endotoxin in
home dust

Allergic
sensitization
and eczema

Increasing endotoxin exposure
is associated
with reduced risk of
allergic sensitization

Melén et al. [3]

Birth cohort study

Air pollution from
local traffic

Allergic
disease and
inflammatory
response

Long term exposure to
traffic pollutions
can increase allergy
sensitization

Lawlis et al.

[10]

Online survey of principals
on school allergy awareness

School environment

Food-induced
allergic
reactions
(i.e. anaphylaxis)
from milk, eggs,
peanuts,& seafood

Detailed awareness and
management
guidelines are integral for
schools to adequately
manage foodinduced allergic
reactions, in the
school environment

Makhija
et al.

[11]

Questionnaires on home
demographics of mothers
and fathers of food allergic
children

Home environment
and
demographic
characteristics

Eczema, atopic
diseases, & food
allergies

Parents of food allergic
children found
higher rates of sensitization to
foods and aeroallergens
compared with the
general population

Majowicz
et al. [12]

Conceptual model

Built and natural
environment

Foodborne illness,
food insecurity,
obesity, & food
allergy

Health practitioners should
consider how targeted
public health actions produce
positive or negative population
health impacts

Ben- Shoshan
et al.

[13]

Telephone survey of individuals
with probable self
reported food allergies

Personal/family
history of atopy,
sociodemographi cs,
& lifestyle habits

Food allergy (i.e.
milk, egg,
peanut, tree nut,
shellfish, fish,
wheat, soy,
or sesame)

Development of eczema in
the first 2 years of
life is consistently
associated with food allergies

Bedolla- Barajas
et al.

[14]

Questionnaire to parents of
children (6-14 yr.)
needing allergy treatment

Demographic and
clinical
data history

Oral allergy
syndrome
(OAS)

OAS is not uncommon
in our
environment; pineapple was the
main food related .
Quercus sp. was the pollen
associated

Xu et al. [15]

Questionnaire to parents
of Chinese
children (3-6 yr.)
with atopic dermatitis

Home environment

Atopic
dermatitis

Home renovation/ redecoration,
new furniture, indoor mold,
urban residency, heredity
disposition and
food allergy can be risk factors for
childhood allergy development

Table 2: Summary of the research articles from the peer-reviewed literature that relates an environmental factor to the onset of an allergic reaction, sensitization, or disease.

Conclusion

In conclusion, food allergies are a field that more research needs to be done in.

A lot of studies done own found correlations but own failed to prove causation. It is known that asthma can increase the risk of developing food allergies. There is also evidence supporting the environment playing a role but to what extent is still unknown and still being studied. Without causations and known ways to prevent food allergies, the epidemic will continue to grow and continue to affect millions of people.

References

Results

Using this search strategy, we identified a entire of 569 unique articles in English, while carefully eliminating any frequencies in search results among and between the search engines employed.

After other exclusion criteria were accounted for, 11 articles remained for review. The bibliographies of these 11 papers were also examined for additional relevant articles, but relevant cited articles were already captured in the initial analyses. These articles are limited to research studies with experimental designs and are summarized in Table 2. Our analysis is outlined as follows: first, brief overviews of Individual allergens, their prevalence and diagnoses; historical perspectives (Current era vs. past eras), discussion of Allergy vs. intolerance/sensitivity, and Known causes and pre-existing health conditions are discussed.

Second, the five working hypotheses in this field of study are explained. Third, the environmental factors contributing to the onset of food allergies are proposed.

Paper Reference

Brief Study Design

Environmental Factor
Measure

Human Health
Measure

Result

Gern et al. [5]

Pet exposure in the home
compared against
cytokine secretion in infants

Dogs

Indicators of atopy

Having a dog in infancy is
associated with higher
cytokine secretion
profiles and reduced allergic
sensitization

Kilpelainen et al.

[7]

Self-reported wheezing from
Finnish students
(18-24 yr.) collected via
questionnaire

Childhood farm
environment

Food allergy,
allergic
rhinitis and/or
allergic
conjunctivitis

The childhood farm
environment independently
reduced the risk for physician-
diagnosed allergies

Liu et al. [8]

Sensitization measured by
skin prick on Chinese
twin pairs (12-28 yr.)

Living conditions,
environment,

and genetics

Peanut and
shellfish food
sensitization

Sensitivity to common food
allergens is influenced
by genetic and
environmental f actors

Leynaert et al.

[6]

Questionnaire on farm
exposure in childhood in
2 French centers

Childhood farm
environment &
D14 C-159T
polymorphism

Atopic
sensitization

CD14 C-159T and farm
childhood environment
exposure may
modify the development
of atopy

Simpson et al. [9]

Population-based birth
cohort study

Endotoxin in
home dust

Allergic
sensitization
and eczema

Increasing endotoxin exposure
is associated
with reduced risk of
allergic sensitization

Melén et al.

[3]

Birth cohort study

Air pollution from
local traffic

Allergic
disease and
inflammatory
response

Long term exposure to
traffic pollutions
can increase allergy
sensitization

Lawlis et al. [10]

Online survey of principals
on school allergy awareness

School environment

Food-induced
allergic
reactions
(i.e. anaphylaxis)
from milk, eggs,
peanuts,& seafood

Detailed awareness and
management
guidelines are integral for
schools to adequately
manage foodinduced allergic
reactions, in the
school environment

Makhija
et al.

[11]

Questionnaires on home
demographics of mothers
and fathers of food allergic
children

Home environment
and
demographic
characteristics

Eczema, atopic
diseases, & food
allergies

Parents of food allergic
children found
higher rates of sensitization to
foods and aeroallergens
compared with the
general population

Majowicz
et al. [12]

Conceptual model

Built and natural
environment

Foodborne illness,
food insecurity,
obesity, & food
allergy

Health practitioners should
consider how targeted
public health actions produce
positive or negative population
health impacts

Ben- Shoshan
et al.

What is the hygiene hypothesis and what does it own to do with food allergies

[13]

Telephone survey of individuals
with probable self
reported food allergies

Personal/family
history of atopy,
sociodemographi cs,
& lifestyle habits

Food allergy (i.e.
milk, egg,
peanut, tree nut,
shellfish, fish,
wheat, soy,
or sesame)

Development of eczema in
the first 2 years of
life is consistently
associated with food allergies

Bedolla- Barajas
et al. [14]

Questionnaire to parents of
children (6-14 yr.)
needing allergy treatment

Demographic and
clinical
data history

Oral allergy
syndrome
(OAS)

OAS is not uncommon
in our
environment; pineapple was the
main food related .

Quercus sp. was the pollen
associated

Xu et al. [15]

Questionnaire to parents
of Chinese
children (3-6 yr.)
with atopic dermatitis

Home environment

Atopic
dermatitis

Home renovation/ redecoration,
new furniture, indoor mold,
urban residency, heredity
disposition and
food allergy can be risk factors for
childhood allergy development

Table 2: Summary of the research articles from the peer-reviewed literature that relates an environmental factor to the onset of an allergic reaction, sensitization, or disease.

Conclusion

In conclusion, food allergies are a field that more research needs to be done in.

A lot of studies done own found correlations but own failed to prove causation. It is known that asthma can increase the risk of developing food allergies. There is also evidence supporting the environment playing a role but to what extent is still unknown and still being studied. Without causations and known ways to prevent food allergies, the epidemic will continue to grow and continue to affect millions of people.

References

  • Stefka AT, Feehley T, Tripathi P, et al. Commensal bacteria protect against food allergen sensitization. Proceedings of the National Academy of Sciences 111 (2014): 13145-13150.
  • Du Toit G, Roberts G, Sayre PH, et al.

    Randomized trial of peanut consumption in infants at risk for peanut allergy. New England Journal Medicine (2015): 803-813.

  • Weiss C, Muñoz-Furlong A, Furlong TJ, et al. Impact of food allergies on school nursing practice. The Journal of School Nursing 20 (2004): 268-278.
  • Bedolla-Barajas M, Kestler-Gramajo A, Alcalá-Padilla G, et al. Prevalence of oral allergy syndrome in children with allergic diseases. Allergologia et Immunopathologia 45 (2017): 127-133.
  • Sicherer SH, Muñoz-Furlong A, Godbold JH, et al. Us prevalence of self-reported peanut, tree nut, and sesame allergy: 11-year follow-up.

    Journal of Allergy and Clinical Immunology 125 (2010): 1322-1326.

  • Gern JE, Reardon CL, Hoffjan S, et al. Effects of dog ownership and genotype on immune development and atopy in infancy. Journal of Allergy and Clinical Immunology 113 (2004): 307-314.
  • Wjst M. Another explanation for the low allergy rate in the rural alpine foothills. Clinical and Molecular Allergy 3 (2005): 7.
  • Sporik R, Hill DJ, Hosking CS.

    Specificity of allergen skin testing in predicting positive open food challenges to milk, egg and peanut in children. Clinical & Experimental Allergy 30 (2000): 1541- 1546.

  • Cummings AJ, Knibb RC, King RM, et al. The psychosocial impact of food allergy and food hypersensitivity in children, adolescents and their families: A review. Allergy 65 (2010): 933-945.
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    Residential risk factors for atopic dermatitis in 3-to 6-year ancient children: A cross-sectional study in shanghai, china. International Journal of Environmental Research and Public Health (2016): 13.

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    Health-related quality of life among adolescents with allergy-like conditions?with emphasis on food hypersensitivity. Health and Quality of Life Outcomes 2 (2004): 65.

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Figure 1: The progression of food allergy diagnosis. This figure shows the possible interactions a body can own to an allergen. The three stages are: no sensitivity to the food, food sensitivity, and food allergy.

Figure 2: Steps to overcome sensitivity related illness.

Figure 3: (A) Current hypothesized associations between food allergies and external factors and articles associated with them.

(B) Greatest number of papers published from search databases used versus the food allergy hypothesis number.

How can you recognise and avoid incompatible foods

Anyone who has an allergy or intolerance towards a food needs to study ingredients lists and change their diet. The genuine challenge in numerous cases, however, is to discover out exactly what it is that you cannot tolerate. We can tell you how to do that.

Harvard scientists own recently evaluated 2.7 million files of American patients.

Their result: Around four percent of every people suffer from some helpful of food allergy[1]. For Germany, similar numbers are available, and according to the German Nutrition Society, three to four percent of adults own an allergy towards food[2]. Significantly more common are food intolerances such as lactose intolerance which affect 15 to 20 percent of every people.

Concerned individuals must carefully study ingredient lists to stop any nasty surprises after dinner that can range from stomach rumbling, severe flatulence, rashes and dizziness to anaphylactic shock.

And it is not always simple to associate a specific foodstuff with the symptoms. The consequence: people finish up not finding out what is lacking in them.

In this article you will study what happens when you own a food allergy in the body, what symptoms are indicative of an allergy, and how you can get back on track with a blood test and an elimination diet. Also: the types, symptoms and treatment of food intolerances.

Figure 1: The progression of food allergy diagnosis. This figure shows the possible interactions a body can own to an allergen. The three stages are: no sensitivity to the food, food sensitivity, and food allergy.

Figure 2: Steps to overcome sensitivity related illness.

Figure 3: (A) Current hypothesized associations between food allergies and external factors and articles associated with them.

(B) Greatest number of papers published from search databases used versus the food allergy hypothesis number.

How can you recognise and avoid incompatible foods

Anyone who has an allergy or intolerance towards a food needs to study ingredients lists and change their diet. The genuine challenge in numerous cases, however, is to discover out exactly what it is that you cannot tolerate. We can tell you how to do that.

Harvard scientists own recently evaluated 2.7 million files of American patients. Their result: Around four percent of every people suffer from some helpful of food allergy[1].

For Germany, similar numbers are available, and according to the German Nutrition Society, three to four percent of adults own an allergy towards food[2]. Significantly more common are food intolerances such as lactose intolerance which affect 15 to 20 percent of every people.

Concerned individuals must carefully study ingredient lists to stop any nasty surprises after dinner that can range from stomach rumbling, severe flatulence, rashes and dizziness to anaphylactic shock. And it is not always simple to associate a specific foodstuff with the symptoms.

The consequence: people finish up not finding out what is lacking in them.

In this article you will study what happens when you own a food allergy in the body, what symptoms are indicative of an allergy, and how you can get back on track with a blood test and an elimination diet. Also: the types, symptoms and treatment of food intolerances.


Building the immune system

The thought is simple. When babies are inside the womb they own a extremely feeble immune system because they are given protection by their mother’s antibodies. When they exit the womb, though, the immune system must start working for itself. For the immune system to work properly, it is thought that the kid must be exposed to germs so that it has a chance to strengthen, according to the U.S.

Food and Drug istration (FDA).

The thought is similar to the training of a body builder. For a body builder to be capable to lift heavy objects, the muscles must be trained by lifting heavier and heavier objects. If the body builder never trains, then he will be unable to lift a heavy object when asked. The same is thought to be true for the immune system. In capable to fight off infection, the immune system must train by fighting off contaminants found in everyday life.

Systems that aren’t exposed to contaminants own trouble with the heavy lifting of fighting off infections.

Mutius hypothesized that the reason children who are not exposed to germs and bacteria are sicklier is due to how the human immune system evolved. She thinks there are two types of biological defenses. If one of the defense systems isn’t trained or practiced enough to fight off illness, the other system overcompensates and creates an allergic reaction to harmless substances love pollen.

Research by other scientists has found similar results.

Exposure to germs triggered an internal inflammatory response in children who were raised in cleaner environments, leading to ailments such as asthma, according to a 2002 article in Science magazine.

One researcher has personal experience has leads him to back the hygiene hypothesis. «I believe that there is a role in the development of a child’s immunity exposure to various germs and a vast microbiome diversity,» said Dr. Niket Sonpal, an assistant professor of clinical medicine at Touro College of Osteopathic Medicine, Harlem Campus. «I was born in India but moved to the U.S. and went to college in Virginia and medical school in Europe.

I am certain that the vast change in environment has played a role in my immunity. How has it? I don’t ponder we know just yet.»

In 1997, some began to question if there is a correlation between the hygiene hypothesis and vaccinations. The number of children getting vaccinations was going up, but so were the number of children afflicted with allergies, eczema and other problems. Could depriving the developing immune system of infections using vaccines cause the immune system to eventually attack itself and cause autoimmune diseases love asthma and diabetes? This is a highly contested issue.

Three studies conducted in the 1990s showed that vaccines had no correlation with children developing allergies and other ailments later in life.

In fact, vaccinations may assist prevent asthma and other health problems other than the diseases they were intended to prevent, according to The National Middle for Immunization Research and Surveillance. The thought that vaccinations can cause health problems does not consider the fact that children, whether vaccinated or not, are still exposed to pathogens that assist build the immune system. These pathogens also own no relation to the diseases that the vaccines prevent.


How does a food allergy develop?

Allergies are today talked of as a disease of modern civilisation. The number of allergic diseases has increased over recent decades more and more.

Scientists are not fairly certain why that is. A favorite explanation is the hygiene hypothesis, which has put the blame for allergies on a modern lifestyle away from dirt and germs[7]. Nevertheless, genetic factors also seem to frolic a role.

What role do the intestines frolic in the development of allergies?

The microbiome (archaically known as the intestinal flora) describes the composition of the billions of bacteria that inhabit our gut.

This microbiome plays a key role in helping our immune system develop from earliest childhood onwards. Researchers propose that our modern way of life affects intestinal bacteria, which in turn can own an impact on the development of allergies[12].

A study from Estonia showed that Estonian children, who still grow up relatively frequently on farms and spend a lot of time outdoors, own a much better bacterial colonisation of their intestines than children from Sweden, who are less likely to grow up on farms[10].

Does breast milk protect us from allergies?

For the immune system to develop healthily, it is ideal for mothers to breastfeed their infants for at least four months.

Until just a few years ago, strict nutritional guidelines were recommended. To reduce the risk of allergies, breastfeeding women had to avoid eggs, nuts, dairy products and wheat products. Experts also advised against touching baby porridge with their gluten-containing grains. And fish was just as much taboo, as sometimes were celery or carrots.

New studies own turned these recommendations on their head. They showed that children are more likely to tolerate foods if they own been in contact with them while still in the womb or breastfeeding[11].

Of course, this only applies if the kid has not already developed an allergy!

And this is excellent to know: Since if your baby has a food allergy, you, as its mom, should also avoid that food during breastfeeding.

Does dirt protect us from allergies?

The hygiene hypothesis is based on the observation that allergies are particularly prevalent in cities and much less common among children raised on a farm.

The theory goes that in the hygienic environments we inhabit in the Western world, our immune system seldom encounters foreign bodies such as pathogens, worms, and parasites. The defences own little meaningful to do and only rarely use their powers to defend themselves against harmless substances such as food and pollen – and this is how an allergy arises[2, 7, 9].

And this is excellent to know: whether we develop an allergy over the course of our lives is decided during the first months of life, and perhaps even in the womb. It therefore depends on the environment in which babies live at the beginning of their lives – and later holidays on the farm will not be capable to prevent any allergies.

Are allergies inherited?

As a law, nobody is born with an allergy.

But humans can own an inherited predisposition towards developing an allergy. In other words, you can own a significantly higher risk of developing an allergy. This often applies to allergies in general, i.e.: the children of parents with hay fever are susceptible to every allergies, whether it be against pollen, animal hair or food. This also applies to other so-called topical or contact diseases, which are closely related to allergies and which often happen together with them (such as with atopic dermatitis and asthma)[2, 8, 14].

And this is excellent to know: as an unborn baby, the womb is our home — and this influences how our body develops.

As such, the mother’s diet can also influence the development of allergies. Birth by caesarean section and a high age of the mom also seem to increase the risk of developing a food allergy[8].

How to prevent an allergy

The appearance of an allergy is a complicated process that scientists still do not fully understand. There are no binding recommendations for preventing allergies.

Medical guidelines, however, provide recommendations that make an allergy a little less likely. They are aimed at «»families at risk»», i.e.

at families in whom allergic diseases, atopic dermatitis or asthma also happen. Recommendations also include[15]:

  1. You should not hold a cat as a pet — unless the kid is at a high risk of developing a cat allergy. In this case an early contact can actually own a positive effect.
  2. Pregnant, breastfeeding and children should not come into contact with mould.
  3. That the mom and kid should not refrain from allergens in the diet, since even the consumption of fish by the mom can exert a protective effect.
  4. From pregnancy, mothers should also avoid tobacco smoke.
  5. You should be exposed to as little vehicle exhaust as possible


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