What are food allergies/sensitivities
Having a kid evaluated as soon as possible will identify the offending food and permit parents to eliminate it from the child's diet. Numerous allergists, or doctors who specialize in allergies, will do a skin-prick test followed by a blood test. The skin-prick test is a series of pricks on the child's skin with a plastic applicator that contains a single food in concentrated form. A food allergy has been identified if the child's skin reacts by welting or becoming red.
The skin-prick test for foods (not for aeroallergens) has a high incidence of untrue positives; that is, the test may be positive but the kid is not truly allergic, or does not own symptoms from the food. This test is not used on a kid with severe anaphylactic reactions or on children with widespread eczema, a skin disorder.
The allergist may also do a food challenge in the doctor's office. The kid is fed the suspected food in increasing amounts to see what helpful of reaction occurs.
One of the tests allergists use is called the RAST (Radio-Allergo-Sorbent Test). It measures the quantity of IgE antibody in the blood that is produced for certain known food allergens.
Love the skin-prick test, RAST and other antibody tests own a high rate of untrue positives.
Some doctors will put the kid on an elimination diet for one week to 10 days. The basic elimination diet is a series of foods that own proven not to be allergy triggers.
This diet consists of foods such as lamb, poultry, rice, vegetables, and every fruits, except citrus and berries. One new food is introduced each week. Parents record the child's reaction to each food. If the kid has no reaction, the food is considered safe and can remain in the diet.
If there is a reaction, it is noted and the food is removed. The kid continues the elimination diet for a few more days, at which time another food is introduced. The elimination diet is often done after skin testing, so there is a logical guide for what to eliminate.
There are several shop-bought tests available that claim to detect allergies, but should be avoided.
- kinesiology testing – claims to detect food allergies by studying your muscle responses
- vega testing – claims to detect allergies by measuring changes in your electromagnetic field
- hair analysis – claims to detect food allergies by taking a sample of your hair and running a series of tests on it
- alternative blood tests (leukocytotoxic tests) – claim to detect food allergies by checking for the «swelling of white blood cells»
Many alternative testing kits are expensive, the scientific principles they are allegedly based on are unproven, and independent reviews own found them to be unreliable.
They should therefore be avoided.
Food allergies can start in adulthood.
No food allergies now? Don’t assume that will always be true.
Food allergies are more common in children than in adults. While “most kids grow out of milk and egg allergies,” says Ciaccio, “a lot of people never grow out of peanut, tree nut, and shellfish allergies.”
But food allergies can start at any age.
Shellfish allergy is the most likely to strike adults. One study found that shellfish was responsible for roughly half of adult-onset food allergies.
An allergy isn’t just any reaction to food.
“A food allergy is an inappropriate immune response to a harmless protein in a food,” explains Roxanne Oriel, a physician and assistant professor of pediatrics, allergy and immunology at the Icahn School of Medicine at Mount Sinai Hospital in New York.
To assist diagnose an allergy, doctors may use a skin prick test or a blood test that measures antibodies called immunoglobulin E (IgE).
IgE is the alarm system that alerts certain immune cells that invaders own arrived.
Many doctors don’t know how to diagnose allergies.
Ever had a panel test, where a doctor uses skin pricks or blood samples to measure your IgE levels in response to a variety of foods?
That approach is backwards, says Oriel. “Never, ever do panels.”
Those tests only tell if your immune cells are sensitized—that is, if they’ve been primed to react to a food. But if they’ve been sensitized and you’ve had no symptoms, you aren’t allergic.
That may be news to your doctor.
In a survey of 407 primary care physicians, 32 percent incorrectly believed that blood or skin prick tests alone were sufficient to diagnose a food allergy.
“When I’m diagnosing a patient, I enquire about what they ate, the symptoms they had, if they’ve reacted more than one time to that food, and so on,” says Oriel.
“That history serves as a guide for what, if anything, I decide to test for using skin prick or blood tests.”
But even then, those tests aren’t perfect, adds Oriel.
“If there is a compelling history and the skin or blood test shows that you’re not sensitized, I would more than likely do a food challenge before saying ‘Go ahead and eat it.’”
A food challenge—watching for symptoms after a patient eats a food—is the gold standard for diagnosing a food allergy.
But they’re time consuming and done only in clinics that can handle a severe allergic reaction.
What about IgG panels, applied kinesiology, electrodermal testing, mediator release testing, and other tests that are offered online or by alternative health practitioners?
“Those tests aren’t dependable and shouldn’t be used to diagnose food allergies,” says Christina Ciaccio, a physician and interim chief of allergy and immunology at the University of Chicago Medical Middle.
The National Academy of Medicine agrees.
It’s not clear how numerous people own food allergies.
“More than 1 in 10 U.S. adults has a food allergy, study finds,” ran the CNN.com headline in January.
That study based its estimates on the symptoms reported by roughly 40,000 people.
(Before the researchers excluded people with non-allergy-like symptoms, almost two out of ten claimed to own a food allergy.)
Ten percent of adults seems “surprisingly high,” notes Ciaccio. Most estimates range from 3 to 9 percent of people of every ages.
“But food allergies in adults own been ignored for a endless time, so we probably don’t own a excellent handle on what’s going on,” says Ciaccio.
And just asking people about symptoms doesn’t yield an precise head count.
“We need studies based on oral food challenges, where a patient eats a suspected food and you diagnose them based on whether or not they own allergic symptoms,” says Oriel.
Are allergies on the rise?
“Almost any allergist, myself included, would tell they are,” says Ciaccio.
“They seem more common and more severe than they used to be. But the evidence isn’t 100 percent convincing.”
Food labels don’t guarantee safety.
“For anyone with a food allergy, eating becomes incredibly restrictive because they don’t know if foods that were prepared exterior the home are safe,” says Ciaccio.
“There’s the fear of accidental ingestion. If you’re at a restaurant and tell you own a peanut allergy, maybe it only gets as far as the wait staff, and it never gets back to the kitchen. And then they serve you a sauce with peanut in it.”
If a packaged food contains one of the eight major food allergens as an ingredient, the label must list the common name of the allergen in the ingredient list—“whey (milk),” for example—or bear a statement love “Contains milk.” (The Middle for Science in the Public Interest, Nutrition Action’s publisher, has asked the FDA to add sesame to the major-allergens list.)
But cross-contamination can happen if companies use the same equipment to make foods with and without allergens.
Whether or not the food actually contains an allergen, “some companies slap a label on it that says something love ‘May contain’ or ‘Processed in a facility that also processes,’” says Ciaccio.
But those labels aren’t required.
So their absence doesn’t guarantee that a food is free of allergens.
Allergy symptoms can vary.
“Most people with IgE-based allergies develop symptoms within two hours of eating the food,” says Oriel.
Allergic symptoms are triggered by the immune system’s response to the “foreign” protein. “Food allergy symptoms can range from mild, love a few hives, to severe and potentially fatal, love anaphylaxis,” says Oriel.
Anaphylaxis is life threatening because your airway narrows, blocking your air supply. That’s why some people with allergies carry a device love an EpiPen, to inject themselves with epinephrine to reverse an anaphylactic reaction.
And don’t assume that if your final reaction was mild, the next one will also be, adds Oriel.
“Your symptoms can be more mild or more severe than before.”
Almost any protein in food can trigger an allergic reaction—that is, can act as an allergen. But eight foods account for the lion’s share: peanuts, milk, eggs, wheat, soy, tree nuts, fish, and crustacean shellfish (like shrimp, crabs, and lobster). Every eight must be declared on food labels.
New therapies are on the way.
Is there a way to make allergies less deadly? Researchers are testing oral immunotherapy, which feeds people tiny, increasing doses of an offending food.
“The goal is to lift the threshold at which your allergy cells release histamine,” Oriel explains.
In a recent company-funded study across 10 countries in North America and Europe, researchers randomly assigned roughly 500 children (aged four to 17) with a peanut allergy to take a placebo or AR101, a peanut protein powder, in doses ranging from 3 to 300 milligrams a day.
After a year, 67 percent of the children who took AR101—but only 4 percent of the placebo takers—were capable to eat roughly two peanuts safely.
“It’s not a cure,” says Ciaccio, who co-authored the study.
“It’s what we call ‘bite safe.’ If they own a bite of a food that contains peanuts, it’s unlikely to be fatal.” (AR101 is currently under review by the FDA.)
“Many other exciting treatments are on the horizon,” says Oriel. “That includes other forms of immunotherapy, a possible peanut allergy vaccine, and more.
We could be having a extremely diverse conversation about food allergies a year from now.”
Illustration: adapted from the Royal Society of Biology/ https://thebiologist.rsb.org.uk/biologist/158-biologist/features/1512-focus-on-allergies.
The information in this post first appeared in the May 2019 issue of Nutrition Action Healthletter.
Find this article exciting and useful?
Nutrition Action Healthletter subscribers regularly get sound, timely information about staying healthy with diet and exercise, yummy recipes, and the inside scoop on healthy and unhealthy foods in supermarkets and restaurants.
If you don’t already subscribe to the world’s most favorite nutrition newsletter, click here to join hundreds of thousands of fellow health-conscious consumers.
Have a comment, question, or idea?
Send us an email at[email protected]. While we can’t reply to every email, we’ll be certain to read your message.
Food allergies and sensitivities
A food allergy or sensitivity is a person's immune system reaction to eating a specific food.
The expression allergy comes from two Greek words: alos, meaning "other" and argon, meaning "action." When one has an allergy, he or she has a reaction other than the one expected.
Food allergies and sensitivities are the body's reaction to a specific food. In a food allergy or sensitivity, when the kid eats a specific food, (such as eggs, for example) generally by the time the eggs reach the stomach or the intestines, the body reads the presence of eggs as an allergen (something harmful).
It sends out immunoglobulin E (IgE), an antibody, to destroy the eggs and protect the body, releasing histamines. The body remembers and produces histamines every time the food is eaten. These histamines trigger allergic symptoms that affect numerous areas of the body, particularly the skin, respiratory system, nervous system, and digestive system. Digestive disorders after eating specific foods are not always allergies. These reactions can be food sensitivities or intolerances.
They can also be symptoms of other, more serious digestive diseases and malfunctions.
In the United states, 90 percent of every food allergies are caused by wheat, peanuts, nuts, milk, eggs, shellfish, soy, and fish. Numerous other foods can be at the root of food allergies or sensitivities, especially berries and other fruits, tomatoes, corn, and some meats love pork. Migraine headaches own been associated with sensitivities to chemicals contained in red wine, deli meats, aged cheeses, and the tannins in tea.
Generally, when a kid is allergic to one food in a food family, he or she will most likely react to other foods in that food family. For example, if a kid is sensitive to one type of fish, he or she also may be sensitive to other types of fish. This is called cross-reactivity.
Referral to an allergy clinic
If your GP suspects a food allergy, you may be referred to an allergy clinic for testing.
The tests needed can vary, depending on the type of allergy:
- if the symptoms developed quickly (an IgE-mediated food allergy) – you’ll probably be given a skin-prick test or a blood test
- if the symptoms developed more slowly (non-IgE-mediated food allergy) – you’ll probably be put on a food elimination diet
An alternative to a skin-prick test is a blood test, which measures the quantity of allergic antibodies in the blood.
During a skin-prick test, drops of standardised extracts of foods are placed on the arm.
The skin is then pierced with a small lancet, which allows the allergen to come into contact with the cells of your immune system.
Occasionally, your doctor may perform the test using a sample of the food thought to cause a reaction.
Itching, redness and swelling generally indicates a positive reaction. This test is generally painless.
A skin-prick test does own a little theoretical chance of causing anaphylaxis, but testing will be carried out where there are facilities to deal with this – usually an allergy clinic, hospital, or larger GP surgery.
Food elimination diet
In a food elimination diet, the food thought to own caused the allergic reaction is withdrawn from your diet for 2 to 6 weeks.
The food is then reintroduced.
If the symptoms go away when the food is withdrawn but return once the food is introduced again, this normally suggests a food allergy or intolerance.
Before starting the diet, you should be given advice from a dietitian on issues such as:
- if any alternative sources of nutrition are needed
- how you should interpret food labels
- the food and drinks you need to avoid
- how endless the diet should final
Don’t attempt a food elimination diet by yourself without discussing it with a qualified health professional.
Almost three million children in the United States own been diagnosed with food allergies.
Almost 600,000 of them own severe allergies to peanuts and possibly twice as numerous own severe shellfish allergies. Each year about 200 adults and children in the United States die from food-related anaphylaxis , an extreme reaction that causes swelling of the throat and bronchial passages, shock, and a severe drop in blood pressure. Nevertheless, food allergies tend to be under-diagnosed by doctors.
Genetics seems to frolic a part in food allergies. If one parent has a food allergy, the child's risk of having a food allergy is doubled. If both parents own food allergies, the risk is even higher. The kid, however, may be allergic to a completely diverse food from the one to which the parent has demonstrated sensitivity.
There also is increased risk when there are other kinds of allergy-related diseases in the family, such as hay fever or asthma .
Causes and symptoms
Food allergies and sensitivities can produce a wide range of symptoms involving the skin, respiratory system, and nervous system. Children may own watery eyes, runny noses, and sneezing.
Skin rashes or hives can range from measles-like rashes to itchy welts. The rashes or welts can appear on a specific part of the body or can be widespread.
Some children own swelling of the eyes, lips, and/or tongue.
Symptoms vary among children, even those who are sensitive to the same food. One child's specific reaction to an offending food does not mean that every children react the same. Nut allergies and shellfish, however, seem to be the most documented triggers for anaphylaxis. Nevertheless, anaphylaxis is not limited to those foods. IgE-mediated allergic reactions can progress to other allergic symptoms. For example, a kid who has had hives is at risk for angioedema (swelling of the blood vessels) and anaphylaxis.
Symptoms also vary in intensity and by the quantity eaten. One kid may own a mild rash on the forearms when eating half a dozen strawberries.
Another may be covered with a rash after eating only one. This variation is individualized and is a factor in the body's sensitivity to the target food.
Although the time between ingestion and symptoms is somewhat variable for allergic reactions (IgE-mediated), the vast majority happen within minutes. Almost every happen within two hours. Reactions due to intolerances, love lactose, may happen somewhat later. Symptoms occurring days after a food is ingested are not likely related to the food.
Allergies are caused by the immune system's reaction to a specific food.
Generally, a kid will own had a prior exposure before IgE or specific histamines are produced.
Food intolerance is often put into the same category as food allergy, even though there may be an entirely diverse mechanism involved. In these cases, the digestive tract reacts to a specific part of the food; for example, the protein or the sugar in a specific food. The digestive system rebels, resulting in gas, bloating, upset stomach, diarrhea , nausea , or vomiting .
Numerous times, these responses are due to eating food contaminated with bacteria, rather than a true food allergy. In other cases, the child's reaction is due to an underlying digestive disorder such as irritable bowel syndrome , which is a chronic condition that is often triggered by specific types of food.
Gluten intolerance is not an allergy. It is a disease called celiac disease , or gluten-sensitive enteropathy. The body cannot process gluten found in wheat and other grains. Though the immune system is involved, celiac disease does not act as a true allergy. Its treatment is love numerous food allergies, namely avoidance of the offending substance, which in this case is gluten.
Some children may lack a specific enzyme needed to metabolize certain foods. About 10 percent of every adults and older children own lactose intolerance . There are two forms of lactose intolerance: inherited and acquired. The inherited form (autosomal recessive) is extremely rare and severe.
The acquired type is extremely common, and occurs in older children (not infants) and adults. It is distressing, but not life-threatening, and occurs with increased frequency in African Americans.
Sometimes infants, as well as older children and adults, own a transient lactose deficiency after an episode of diarrhea.
Children with lactose intolerance own a lactase deficiency that keeps them from processing milk and milk products. These children can often drink milk that has had this enzyme introduced into the product. Some children can drink milk that has acidophilus bacteria put into it. This bacteria breaks below the lactose, or milk sugar, in the milk so that the kid can tolerate it.
Some children with lactose intolerance cannot drink whole milk, but can eat cheese or drink low-fat buttermilk in little quantities. This is diverse from a true milk allergy where even a little quantity of any dairy product will produce a reaction.
Some children may also be intolerant of food colorings, additives, and preservatives. Among these are yellow dye number 5, which can cause hives ; and monosodium glutamate, which produces flushing, headaches, and chest pain . Sulfites, another additive, own been found to cause asthmatic reactions and even anaphylactoid reactions.
Sulfites are preservatives used in wines, maraschino cherries, seafood, and soft drinks. They are sometimes put on unused fruits and lettuce to maintain their unused appearance, on red meats to prevent brown discoloration, and even in prepared deli foods love crab salad. Sulfites appear on food labels as sodium sulfite, sodium bisulfite, potassium bisulfite, sulfur dioxide, and potassium metabisulfite. The U.S. Food and Drug istration (FDA) has banned the use of sulfites as a preservative for fruits and vegetables, but they are still in use in some foods.
When to call the doctor
Anaphylaxis is an extreme reaction to a food, generally peanuts or nuts.
It causes swelling of the throat and bronchial passages, a drop in blood pressure, shock, and even death. A kid with anaphylaxis should be taken to the emergency room immediately. If an emergency epinephrine pen is available, it should be istered immediately.
If a kid experiences any type of allergy symptoms after eating, the kid should be evaluated. Of specific concern are digestive symptoms that hold the kid from eating properly or cause the kid to lose weight. Equally significant are neurological symptoms, especially headaches.
Digestive and neurological symptoms could also be an indication of other underlying disorders. Therefore, the kid should be seen by a doctor.