There is much ambiguity about the differences (and similarities) between food allergies and food intolerances. There are many ways that food can affect someone adversely, with the reactions that occur anywhere between a few minutes to a few days after consumption. Those who react rapidly to a food most likely are experiencing an allergic food reaction. This type of reaction involves the immune system. For instance, if you have an allergic reaction to shellfish, your body will overproduce an certain immunoglobulin (IgE) to proteins on the shellfish which travel to cells that release chemicals, causing an allergic reaction. A food allergy can cause a serious or even life-threatening reaction by eating a microscopic amount, touching or inhaling the food. Hives, difficulty breathing and anaphylaxis are associated with this type of reaction. According to a study released in 2013 by the Centers for Disease Control and Prevention, food allergies among children increased approximately 50% between 1997 and 2011. Six foods accounted for 90 percent of all reactions: milk, eggs, nuts, soy, wheat and shellfish. I suspect that this rise in reactivity has to do with controversial animal husbandry practices and/or the presence of preservatives, dyes, GMOs and unnatural chemical biproducts in our foods, but this is a topic for another day.
Food intolerances are more subtle and much more insidious. Eating a food you are intolerant to can leave you feeling miserable. Migraines, eczema, psoriasis, joint pain, emotional disturbances, ADHD, depression, inflammatory bowel syndrome, gas and bloating, allergies and many other health issues persist due to consumption of hidden intolerances. Reactions to foods may take place three days after eating the food, making the offending food difficult to identify. A food intolerance response takes place in the digestive system. It occurs when you are unable to properly breakdown the food. This could be due to enzyme deficiencies, secondary immune responses such as an increase in cytokines (inflammatory compounds), sensitivity to food additives or reactions to naturally occurring chemicals in foods. Because of the time lag associated with reactivity, most people innocently continue to eat the offending food; constant exposure results in “leaky gut”, a phenomenon in which the gastrointestinal tract becomes inflamed. If the swelling persists, the gastrointestinal tract begins to lose its integrity, which allows foods that are not fully digested to pass into the blood stream, creating further havoc for the immune system. Like food allergies, food intolerances may also lead to an increase in immunoglobulins, IgG and IgA.
In general there are two approaches to recognition of the offending food(s). One method, the gold standard, is the elimination diet. An elimination diet involves removal of all of the most likely candidates for six weeks and observance for any improvement in symptoms. After significant improvement is noted, (but not before the six weeks are completed) the foods are added back in, one at a time, at a rate no faster than one food per week. Any return of symptoms can then be associated with that food. The advantages to this approach include a financial incentive (its free) as well as its precision in successful identification of “bad” foods. The disadvantage lies with the fact that it is extremely time consuming and requires a high degree of patient motivation and compliance.
Laboratory testing is also available. However, these tests are fraught with controversy. Conventional medicine looks for IgE reactions by pricking the skin with a tiny amounts of food and looks for wheels (hives) on the skin, indicating potential reactivity. This test is reproducible, but often misses subclinical reactions. In other words, it is good as catching food allergies, but less reliable if you are looking for food sensitivities. Many physicians instead rely on serum tests whose outcome (e.g. IgG and IgA levels) is associated with food sensitivities. The testing facilities use plates of finely ground up foods that are exposed to the patients’ serum; lab technicians then observe the plate for a classic immune reaction and arbitrarily designate these reactions as being absent, low or high. A high reaction ostensibly indicated a need to avoid that food. However, the problems that may be associated with this preparation are enormous. For one, all food (organic and non-organic) is coated with microorganisms. The most common of these include bacteria and fungi but viruses and parasites may also be found on fruits, vegetables, grains, milk and meat products. Microorganisms have many antigens that are highly immunogenic. It is common knowledge that most people have high circulating levels of IgG to a number of common microorganisms. To this likely wealth of microorganisms on the testing plates, there is the presence of possible pesticides and organic solvents that are not (according to the technologist interviewed) rinsed away during preparation. All misgivings aside, testing is easy and convenient for both patient and physician. One need only submit a blood sample from the patient and the laboratory returns not only the foods the patient is “allergic to” but a “rotation” or “elimination” diet for the patient. Testing costs between $200 and $500.
A third method of testing, the Alcat Test, uses a similar method to the test previously discussed, with one key difference. Rather than using IgG or IgA to assess reactivity to food, the Alcat test measures reactions to food via stimulation of white blood cells. This is a key difference as food can trigger reactions through many mechanisms, not just via an IgG or IgA response. Supporters of this test feel that white blood cells will cause an inflammatory response regardless of the mechanism by which a food irritates the body; hence it is a more thorough and reliable test that can be used to identify the offending food.
Ultimately, I believe both approaches have their time and place. As ever, consider consulting your friendly neighborhood alternative health practitioner for guidance and advice.