Allergies and Sensitivities
|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.
What are the symptoms of allergies?
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.
What conditions are related to allergies?
According to J. C. Breneman, M.D., author of the book Basics of Food Allergy,2 many health conditions are related to allergies and have been the subject of independent studies. Even so, any relationship between the condition and the allergy needs to be considered with the aid of a doctor. More information about the relationship between specific health conditions and allergies or other sensitivities can be found in the following articles:
The following conditions may also be related to allergies and other sensitivities:
Bed-wetting (Nocturnal enuresis)
Cyclic vomiting syndrome
In a small, preliminary trial, people with IgA nephropathy consumed a hypoallergenic diet (rice, olive oil, turkey, rabbit, lamb, green vegetables, potatoes, pears, apples, salt, and water) for 14 to 23 weeks. Laboratory parameters for kidney function improved significantly, and all participants remained relapse-free while maintaining the diet.104
Multiple Food Protein Intolerance (MFPI) of infancy
Multiple chemical sensitivity
Musculoskeletal pain (including back pain)
Leaky gut syndrome
Dietary changes that may be helpful for allergies and sensitivities
A low-allergen diet, also known as an elimination diet or a hypoallergenic diet is often recommended to people with suspected food allergies to find out if avoiding foods that commonly trigger allergies will provide relief from symptoms.118 This diet eliminates foods and food additives considered to be common allergens, such as wheat, dairy, eggs, corn, soy, citrus fruits, nuts, peanuts, tomatoes, food coloring and preservatives, coffee, and chocolate. Some popular books offer guidance to people who want to attempt this type of diet.119 120 The low-allergen diet is not a treatment for people with food allergies, however. Rather, it is a diagnostic tool used to help discover which foods a person is sensitive to. It is maintained only until a reaction to a food or foods has been diagnosed or ruled out. Once food reactions have been identified, only those foods that are causing a reaction are subsequently avoided; all other foods that had previously been eaten are once again added to the diet. While individual recommendations regarding how long a low-allergen diet should be adhered to vary from five days to three weeks, many nutritionally oriented doctors believe that a two-week trial is generally sufficient for the purpose of diagnosing food reactions.
Strict avoidance of allergenic foods for a period of time (usually months or years) sometimes results in the foods no longer causing allergic reactions.121 Restrictive elimination diets and food reintroduction should be supervised by a qualified healthcare professional.
Lifestyle changes that may be helpful for allergies and sensitivities
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.122 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.
Nutritional supplements that may be helpful for allergies and sensitivities
Probiotics may be important in the control of food allergies because of their ability to improve digestion, by helping the intestinal tract control the absorption of food allergens and/or by changing immune system responses to foods.123 124 125 One group of researchers has reported using probiotics to successfully treat infants with food allergies in two trials: a double-blind trial using Lactobacillus GG bacteria in infant formula, and a preliminary trial giving the same bacteria to nursing mothers.126 Probiotics may also be important in non-allergy types of food intolerance caused by imbalances in the normal intestinal flora.127
Thymomodulin® is a special preparation of the thymus gland of calves. In a double-blind study of allergic children who had successfully completed an elimination diet, 120 mg per day of thymomodulin prevented allergic skin reactions to food and lowered blood levels of antibodies associated with those foods.128 These results confirmed similar findings in an earlier, controlled trial.129
According to one theory, allergies are triggered by partially undigested protein. Proteolytic enzymes may reduce allergy symptoms by further breaking down undigested protein to sizes that are too small to cause allergic reactions.130 Preliminary human evidence supports this theory.131 Hydrochloric acid secreted by the stomach also helps the digestion of protein, and preliminary research suggests that some people with allergies may not produce adequate amounts of stomach acid.132 133 134 However, no controlled trials have investigated the use of enzyme supplements to improve digestion as a treatment for food allergies.
Many of the effects of allergic reactions are caused by the release of histamine, which is the reason antihistamine medication is often used by allergy sufferers. Some natural substances, such as vitamin C135 136 and flavonoids,137 including quercetin,138 139 have demonstrated antihistamine effects in test tube, animal, and other preliminary studies. However, no research has investigated whether these substances can specifically reduce allergic reactions in humans.
Are there any side effects or interactions with allergies and sensitivities?Refer to the individual supplement for information about any side effects or interactions.
Herbs that may be helpful for allergies and sensitivities
See the articles on specific health conditions listed above for information on the effectiveness of herbs for each condition.
Are there any side effects or interactions with allergies and sensitivities?Refer to the individual herb for information about any side effects or interactions.
Holistic approaches that may be helpful for allergies and sensitivities
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).140 141 142 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.143 Other preliminary trials have also demonstrated positive results.144 One controlled trial reported a reduction in allergic complaints following acupuncture treatment, but the results were not statistically significant.145 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. Preliminary146 147 and double-blind148 149 research suggests treatment of allergies by provocation-neutralization may be effective, though negative double-blind research also exists.150
Allergy treatment using extracts of allergens taken orally is another controversial method advocated by some alternative healthcare practitioners.151 Most152 153 154 155 but not all double-blind trials156 157 have found this approach effective for house dust allergy. Preliminary158 and double-blind159 160 161 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,162 and in one controlled trial163 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.164 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.165 166 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.167
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,168 169 A similar method uses these dilutions under the tongue to test for allergies.170 Double-blind research has not found this method effective. 171
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.172 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.173 Another preliminary study found the Vega test identified the same neutralization doses as clinical ecology testing (see above) in 66% of tests.174 More research is needed to better evaluate these testing techniques.