A food allergy is defined as an abnormal immune reaction caused by the ingestion of a food or food additive. The most dramatic form of food allergy reaction occurs within minutes, usually in response to certain foods such as shellfish, peanuts, or strawberries. The effects are similar to those of a bee sting allergy, involving hives, itching, swelling in the throat, and difficulty breathing; this immediate type of allergic reaction can be life-threatening.

Other food allergy reactions are more delayed, causing relatively subtle symptoms over days or weeks.1 These include gastrointestinal problems (constipation, diarrhea, gas, cramping, and bloating), rashes, and headaches. However, because such delayed reactions are relatively vague and can have other causes, it has remained a controversial subject in medicine.

Some food allergy-like reactions do not actually involve the immune system. These are termed food sensitivities (or food intolerance). In most cases, the cause of such sensitivities is unknown.

Delayed-type food allergies and sensitivities might play a role in many diseases, including asthma, attention deficit disorder, rheumatoid arthritis, vaginal yeast infections, canker sores, colic, ear infections, eczema, irritable bowel syndrome, migraine headaches, psoriasis, chronic sinus infections, ulcerative colitis, Crohn’s disease, and celiac disease.2-9,64, 68 However, not all experts agree; practitioners of natural medicine tend to be more enthusiastic about the food allergy theory of disease than conventional practitioners.

Conventional treatment for immediate-type food allergy reactions includes desensitization (allergy shots), emergency epinephrine (adrenaline) kits for self-injection, and the antihistamine diphenhydramine (Benadryl).

Delayed-type food allergies are much more difficult to identify and treat. Although skin and blood tests are sometimes used, their reliability is questionable.10-16,65,66 A particular blood test called ALCAT has shown some promise, but much more study is necessary to establish its accuracy.17 The  double-blind food challenge is the only truly reliable way to identify delayed-type food allergies. This method uses some means of disguising the possibly allergenic food, usually by mixing it with other, nonallergenic foods. Individuals are randomly given either the possibly allergenic food or placebo on a number of occasions separated by 1 or more days. Neither the physician nor the participant knows which is real possibly allergenic food and which is not. Evaluation of the response can then determine whether an allergic response is really present or not. Studies suggest that perhaps only one-third of people who believe they are allergic to a given food actually experience an allergic reaction when they are given it in a double-blind fashion; in addition, reactions are often milder than individuals believe.18,19

Although it is the most accurate way of determining food allergies, the double-blind food challenge is still mostly used in research. The elimination diet with food challenges (described below) is the most common technique in use.

Another conventional approach for delayed-type food allergies is oral cromolyn (a drug sometimes used in an inhaled form for treating asthma and other allergic illnesses).20 A double-blind, placebo-controlled study of 14 children with milk and other food allergies found that cromolyn was effective in preventing allergic reactions in 11 of 13 cases, whereas placebo was effective in only 3 of 9 cases.21 In another study, 32 individuals were given cromolyn one half hour before meals and at bedtime.22 If their food allergy symptoms were prevented, the participants were entered into a double-blind, placebo-controlled crossover study using cromoglycate. Of the 31 people who completed the study, 24 experienced relief of gastrointestinal symptoms when taking cromolyn as compared to 2 when taking placebo. In addition, systemic allergic reactions were also blocked with the cromolyn. Unfortunately, the drug also had many side effects.

Principal Proposed Natural Treatments

There are no well-documented natural treatments for food allergies. The most obvious approach would be to remove known allergenic foods from the diet. Some alternative practitioners offer lab tests to identify such allergens. However, as described above, no lab tests have been proven accurate for this purpose.

The elimination diet is another approach for identifying allergenic foods. This method involves starting with a highly restricted diet consisting only of foods that are seldom allergenic, such as rice, yams, and turkey. If dietary restriction leads to resolution or improvement of symptoms, foods are then reintroduced one by one to see which, if any, will trigger reactions.23 There is some evidence that the elimination diet may be effective for chronic or recurrent hives;24-26 it has been tried for many other conditions as well, including irritable bowel syndrome,27-34,68asthma,35chronic ear infections,55,56reflux esophagitis,36 and Crohn’s disease.37,38

Still another method involves simply eliminating the most common allergens. Cow’s milk protein intolerance is thought to be the most common childhood allergy,39 followed by allergies to eggs, peanuts, nuts, and fish. Some evidence indicates that use of special hypoallergenic infant formulas rather than cow’s milk formula may help prevent eczema, urticaria, and food-induced digestive distress.40,41,67,69 In addition, eliminating cow’s milk from the diets of breastfeeding infants and their nursing mothers might reduce symptoms of infantile colic,42-51 although not all studies have found benefit.52-54

In hopes of preventing food allergies and diseases related to them, some authorities recommend that pregnant and breastfeeding mothers as well as their children should avoid allergenic foods.57-61 However, it is not clear if this method actually provides any benefit. For example, one study evaluated 165 children at high risk of developing allergic symptoms.62 Careful avoidance of allergenic foods in the diets of the mothers and infants did not reduce the later development of eczema, asthma, hay fever, or food allergy symptoms.

Other Proposed Treatments for Food Allergies and Sensitivities

Digestive enzymes such as bromelain and other proteolytic enzymes have been proposed as a treatment for food allergies, based on the reasonable idea that digesting offending proteins will reduce allergic reactions to them. However, there is no real evidence as yet that they are effective against food allergies.

Thymus extract is a supplement derived from the thymus gland of cows. Highly preliminary evidence suggests that by normalizing immune function, thymus extracts may be helpful for food allergies.63 However, there are significant safety issues, and this study did not prove the supplement to be effective. See the Thymus article for details.

Probiotics (eg, Lactobacillus species) are friendly bacteria that have been studied for their ability to prevent or treat respiratory allergies and various gastrointestinal symptoms, most notably diarrhea. However, at least study found that probiotics were not helpful in treating cow’s milk allergy among infants.70

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