The Co-op Food Stores of New Hampshire and Vermont

added 05/08/11

by Mary Saucier Choate, M.S., R.D., L.D.
Dietitian and Co-op Food and Nutrition Educator

Eight major foods are responsible for 90 percent of emergency room visits due to a food allergy. Can you name them? Do you know the symptoms of a food allergy? Can you tell a food allergy from a food intolerance? Why would you want to know the difference?

The latest food allergy guidelines can help to answer questions about food allergy—starting with correctly identifying whether or not you or your child has one.

The National Institute of Allergy and Infectious Diseases (NIAID) worked with an expert panel made up of scientists and researchers from more than thirty professional, government, and patient health advocacy groups to develop the new “Guidelines for the Diagnosis and Management of Food Allergy in the United States.” The guidelines are based on the “best practices” of up-to-date, science-based research. Becoming familiar with the guidelines can help you to become a more informed health care consumer in this perplexing area.

Food Allergy

A food allergy occurs when a specific food protein causes an immune reaction in an individual. This reaction happens each time the food is consumed. A true food allergy involves two components: an allergic sensitization to the food allergen, and the development of specific signs and symptoms when exposed to that food. Sensitization occurs when an individual produces an antibody specific to a given food allergen. It is possible to be sensitized without having signs or symptoms of an allergic reaction when eating the food. In this case, a true food allergy does not exist.

Food allergies can occur with many foods. However, eight major food allergens cause the majority of reactions in the United States: milk, eggs, peanuts, tree nuts, fish, shellfish, soy, and wheat. Some of these allergies may be outgrown; others, such as peanut and shellfish, will remain lifelong. People with a true food allergy cannot tolerate even a tiny amount of the allergen-containing food without the risk of severe symptoms.

Symptoms of a food allergy may include a rash, hives, or red itchy skin; stuffy or itchy nose, sneezing, or itchy and teary eyes; vomiting, stomach cramps, or diarrhea; and facial swelling. Some people with food allergies can experience a severe, whole-body reaction called anaphylaxis. Anaphylaxis symptoms develop rapidly and may include difficulty breathing, swelling of the throat, confusion, slurred speech, palpitations, weakness, a drop in blood pressure, or loss of consciousness. Anaphylaxis can be life-threatening without proper treatment.

Food Intolerance

Individuals may confuse non-allergic food reactions, such as food intolerance, with food allergies. While some research indicates that up to 35 percent of people reporting a reaction to food believed they had a food allergy, oral food challenge studies suggest that the true incidence is about 3.5 percent. An intolerance, such as lactose intolerance is not a true food allergy. An individual with food intolerance, as opposed to an allergy, can generally consume a small amount of the offending food without experiencing symptoms. The specific amount tolerated may be different for each individual.

The following food intolerances are often mistakenly called food allergies. Some of the symptoms are similar to those of food allergy.

Lactose Intolerance

Lactose intolerance is the inability to properly digest the naturally occurring sugar in milk (lactose). This is caused by missing or low levels of lactase enzymes in the lining of the small intestine. Because the lactose is not broken down effectively, it is fermented by colon bacteria. This results in intestinal gas and causes symptoms of bloating, abdominal pain, and sometimes diarrhea.

Food Additive Sensitivity

A reaction to certain food additives is another kind of food intolerance. Added preservatives and flavor enhancers, such as monosodium glutamate (MSG) and sulfites, can cause symptoms that can be mistaken for food allergy symptoms. In large amounts, MSG can cause temporary symptoms such as flushing, sensations of warmth, headache, and chest discomfort. These temporary reactions occur soon after eating food containing high levels of MSG.

Sulfites may be in the form of preservatives added to foods and also occur naturally in certain foods. Symptoms of sulfite intolerance can occur within 15 to 30 minutes after consumption. Research studies indicate that those mainly at risk of a sulfite reaction are people with severe asthma who depend upon steroid-based asthma control drugs. Adverse reactions to sulfites in people without asthma are extremely rare.

Histamine Toxicity

A person who eats foods with high levels of histamine may show symptoms that are similar to food allergy. Histamine toxicity, known as scombroid poisoning when it involves fish, is a reaction to high levels of histamine in foods. Fish, particularly tuna and mackerel, that are not refrigerated properly may develop high levels of histamine due to bacterial growth. Histamine toxicity has also been associated with aged cheeses and red wines. Elevated levels of histamine can occur naturally in these foods.

Reactions To Certain Foods

Some people develop uncomfortable intestinal gas after eating high-fiber foods such as beans, peas, broccoli, or cabbage. These “gas-producing” foods contain indigestible carbohydrates which are fermented in the colon by gas-producing bacteria. This can be avoided by starting a high-fiber diet slowly and in small portions, gradually increasing the amount of these healthful foods.

Food Poisoning

Some of the symptoms of food allergy, such as abdominal cramping, nausea, and vomiting, are common to food poisoning. Food poisoning, also known as food-borne illness, is caused by harmful microbes, such as viruses, parasites, bacteria, and bacterial toxins that can contaminate food.

Appropriate Testing

According to the NIAID report, skin prick tests, intradermal tests, total serum IgE, and the atopy patch test are not sufficient to provide a correct food allergy diagnosis. The recommended “gold standard” for diagnosing food allergies is the double-blind, placebo-controlled oral food challenge. Because having this test can place you at risk for a severe allergic reaction, it must always be performed by a healthcare professional who has the appropriate experience and resources to perform this test

Allergies in Children

Accurate testing for diagnosis of food allergy is critical. If a food allergy is incorrectly diagnosed in a child, whether by the child’s parents or via insufficient testing as noted in the above report, the child’s diet may be unnecessarily severely restricted, putting the child at risk for vitamin, mineral, and other nutritional deficiencies
If a food allergy is identified, the parents can learn the specific allergenic foods to avoid. They can also receive assistance from a nutrition professional on how to assure adequate nutrition from non-allergenic food choices. In most cases, children outgrow milk, wheat, soy, and egg allergies, but not as often fish, shellfish, tree nut, and peanut allergies. Your child should be re-tested periodically to see whether he or she is still allergic.

Mother’s Diet During Pregnancy and Lactation

The guidelines recommend a normal varied and healthful diet during pregnancy and lactation for optimal infant growth and development. While the panel reported that there is no strong evidence that breast-feeding has a protective role in preventing food allergy, exclusive breast-feeding until four to six months of age has numerous well-documented benefits, unless breast-feeding is inadvisable for medical reasons. The guidelines specifically do not recommend substituting soy infant formula for cow’s milk infant formula as a strategy for preventing food allergy.

Food Allergen Labeling: Good News and Not So Good

Clear, unambiguous labeling is becoming increasingly important as foods are exported and imported, crisscrossing the globe. The panel warns that globalization of the food supply and exposure of Americans to new foods or culinary practices may lead to increases in the number of major food allergens in the United States. Different foods cause allergic reactions in different populations. For example, in the European Union, celery, mustard, sesame, lupine, and molluscan shellfish (oysters, clams, mussels, and scallops) have been identified as major allergens. Buckwheat is a major allergen in Japan, as are chickpeas in India.

The good news is that since the passage of the 2004 Food Allergen Labeling and Consumer Protection Act, food labels on products sold in this country are required to state the presence of any of the eight major food allergens present. The unfortunate news is that the law does not address so-called precautionary labeling. Examples of precautionary labeling are statements such as: “This product may contain trace amounts of milk” or “This product is produced in a factory that also manufactures tree nuts and peanuts.” The problem is that precautionary labeling is voluntary and it is used at the manufacturer’s discretion. This kind of ingredient labeling is not completely effective in preventing unintentional exposure to allergens. The expert panel warns that products with precautionary labeling, such as “this product may contain trace amounts of allergen,” be avoided.

Food Allergy Questions

For up-to-date information on all of your food allergy questions, go to The Food Allergy & Anaphylaxis Network (FAAN) website, www.foodallergy.org.

Should you suspect a food allergy in yourself or your child, be sure to consult the “Guidelines for the Diagnosis and Management of Food Allergy in the United States” for reliable information on proven tests to look for and unproven procedures to avoid. (http://www.niaid.nih.gov/topics/foodAllergy/clinical/Documents/FAGuidelinesExecSummary.pdf)