Allergies and Sensitivities
About This Condition
Allergies are responses mounted by the immune system to a particular food, inhalant (airborne substance), or chemical. In popular terminology, the terms “allergies” and “sensitivities” are often used to mean the same thing, although many sensitivities are not true allergies. The term “sensitivity” is general and may include true allergies, reactions that do not affect the immune system (and therefore are not technically allergies), and reactions for which the cause has yet to be determined.
Some non-allergic types of sensitivity are called intolerances and may be caused by toxins, enzyme inadequacies, drug-like chemical reactions, psychological associations, and other mechanisms.1 Examples of well-understood intolerances are lactose intolerance and phenylketonuria. Environmental sensitivity or intolerance are terms sometimes used for reactions to chemicals found either indoors or outdoors in food, water, medications, cosmetics, perfumes, textiles, building materials, and plastics. Detecting allergies and other sensitivities and then eliminating or reducing exposure to the sources is often a time-consuming and challenging task that is difficult to undertake without the assistance of an expert.
Common symptoms may include itchy, watery eyes; sneezing; headache; fatigue; postnasal drip; runny, stuffy, or itchy nose; sore throat; dark circles under the eyes; an itchy feeling in the mouth or throat; abdominal pain; diarrhea; and the appearance of an itchy, red skin rash. Life-threatening allergic reactions—most commonly to peanuts, nuts, shellfish, and some drugs—are uncommon. When they do occur, initial symptoms may include trouble breathing and difficulty swallowing.
Healthy Lifestyle Tips
People with inhalant allergies are often advised to reduce exposure to common household allergens like dust, mold, and animal dander, in the hope that this will reduce symptoms even if other, non-household allergens cannot be avoided.118 Strategies include removing carpets, frequent cleaning and vacuuming, using special air filters in the home heating system, choosing allergen-reducing bed and pillow coverings, and limiting household pets’ access to sleeping areas.
Acupuncture may be helpful in the treatment of some types of allergy. Studies of mice treated with acupuncture provide evidence of an anti-allergic effect with results similar to treatment with corticosteroids (cortisone-like drugs).119, 120, 121 A preliminary trial found a significant decrease in allergy symptoms following acupuncture treatment. It was found that the decline in symptoms coincided with a decline in laboratory measures of allergy. Relief persisted for two months following the treatment.122 Other preliminary trials have also demonstrated positive results.123 One controlled trial reported a reduction in allergic complaints following acupuncture treatment, but the results were not statistically significant.124 In the future, controlled trials with larger numbers of subjects may help to determine conclusively whether allergies can be successfully treated with acupuncture therapy.
Provocation-neutralization is a controversial method of both allergy testing and treatment. Treatment consists of injecting minute dilutions of foods, inhalants, or (in some cases) chemicals into the lower layers of the skin. This approach is not the same as traditional desensitization injections given by medical allergy specialists. Preliminary125, 126 and double-blind127, 128 research suggests treatment of allergies by provocation-neutralization may be effective, though negative double-blind research also exists.129
Allergy treatment using extracts of allergens taken orally is another controversial method advocated by some alternative healthcare practitioners.130 Most131, 132, 133, 134 but not all double-blind trials135, 136 have found this approach effective for house dust allergy. Preliminary137 and double-blind138, 139, 140 trials have reported success using this method for other allergies as well.
Treatment of food allergy using very small but increasing daily doses of actual foods has been reported,141 and in one controlled trial142 12 of 14 patients successfully completed the program and could tolerate previously allergenic foods.
All desensitization programs require the guidance of a healthcare professional. While none of these approaches has been unequivocally proven, several show promise that people with allergies may be treatable by means other than simple avoidance of the offending food or inhalant substance.
What tests can detect allergies? Several tests or procedures are used by physicians to detect allergies. Most of these tests remain controversial.143 Some clinicians (cited below), however, believe some of these tests can be effective.
This form of testing is one of the most widely used. A patient’s skin is scratched with a needle that contains a portion of the food, inhalant, or chemical that is being tested. After a period of time, the skin is examined for reactions. If there is a reaction, it is determined that an allergy exists. Although this test is accepted by most allergists, scratch testing is subject to a relatively high incidence of inaccurate results, some tests showing positive when the person is not truly allergic to the substance (false positive) and some tests showing negative when an allergy really exists (false negative).
RAST/MAST/PRIST/ELISA (and other tests that measure immunoglobulins)
The radioallergosorbent test (RAST) indirectly measures antibodies in the blood that react to specific foods. It is used by many physicians and has been shown to be a somewhat reliable indicator of allergies.144, 145 It does not, however, help diagnose non-allergic food sensitivities and is therefore associated with a high risk of false negative readings. In an attempt to avoid this problem, a variety of modifications have been made to tests related to RAST (such as MAST, PRIST, and ELISA). Some of these changes may have reduced the risk of false negative readings somewhat but are likely to have increased the risk of false positive readings. A number of conditions associated with food sensitivities, such as migraine headaches and irritable bowel syndrome, have shown remarkably poor correlation between RAST results and the actual sensitivities of patients.
The cytotoxic test views a patient’s serum under a microscope to see whether it is reacting to certain substances. The test is subject to numerous errors and is not generally considered to be reliable.146
Clinical ecology (provocation-neutralization; end-point titration)
This branch of medicine is considered very controversial. Testing is done using intra-dermal (under the skin) injections of minute dilutions of foods, inhalants or (in some cases) chemicals. Based on reactions, additional dilutions are used. This test not only determines whether an allergy exists but also operates on the theory that one dilution can trigger a reaction while another can neutralize a reaction. Preliminary research suggests this approach may have beneficial effects,147, 148 A similar method uses these dilutions under the tongue to test for allergies.149 Double-blind research has not found this method effective. 150
Elimination and reintroduction
The most reliable way to determine a food allergy is to have the patient eliminate a suspected food from the diet for a period of time and then reintroduce it later. Once a food is eliminated, the symptoms it may be causing either improve or resolve, typically after several days to three weeks. The body then becomes more sensitive to the food, so when the food is reintroduced, the symptom is more likely to recur. This tool shows with a high degree of certainty which foods are problem foods. The testing requires a great deal of patience and, as with all other forms of allergy testing, is best undertaken with the help of a physician who can monitor the diet.151 Reintroduction of an allergenic food has been reported to lead occasionally to dangerous reactions in some people with certain conditions, particularly asthma—another reason this approach should not be attempted without supervision.
Bioelectric tests are controversial procedures that attempt to measure changes in electrical activity at acupuncture points when a potential allergen is brought into proximity. A preliminary study reported that the EAV (Electroacupuncture According to Voll) device, also called the Vega test, identified the same allergens as RAST testing in 70.5 percent of tests.152 Another preliminary study found the Vega test identified the same neutralization doses as clinical ecology testing (see above) in 66% of tests.153 More research is needed to better evaluate these testing techniques.
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The information presented in Aisle7 is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. Self-treatment is not recommended for life-threatening conditions that require medical treatment under a doctor's care. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires June 2014.