Dr. Robert F. Kidd
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Dental & General Health
Food sensitivities and allergies:
Hippocrates is supposed to have said: "The secret to good health is to know what to eat, and to know what not to eat." This section is about what we should not eat.
Adverse reactions to certain foods occur in many individuals, and the reactions are not always obvious. This is especially true for the foods that we eat every day. Even though the individual is experiencing symptoms, the symptoms may be present all the time and are therefore considered "normal".
In addition, people react in a variety of ways. A certain food in one person will cause heartburn, in another a skin rash, and in yet another fatigue. These individual vulnerabilities can be explained partly by genetics (these symptoms often run in families), but also by "tissue memory". In other words if a person has in the past experienced a particular symptom, or even collection of symptoms, these symptoms can be triggered or worsened by exposure to a certain food.
A third reason that food sensitivities may be difficult to identify is that the reaction may be delayed, in some cases up to four days after exposure. In contrast, an allergic reaction is immediate. This is one of the main differences between food sensitivities and food allergies. Food sensitivities are therefore often called "delayed food sensitivities".
Food allergy involves a particular component of the immune system, the part that secretes IgE antibodies. The reaction is immediate, may involve hives or running from the nose and eyes, and constriction of the throat. This can be serious, even life-threatening and is the condition that allergists concern themselves with. Testing usually involves patch testing, (scratching the inside of the forearm, applying test reagents to the scratch, and measuring the skin response).
Food sensitivities are different. Another type of immune response occurs, involving IgG and IgA antibodies. As mentioned above, a wide variety of reactions to foods are possible, and the response may be delayed. Also, more than one food may be involved. For these reasons, delayed food sensitivities are harder to identify.
One simple, inexpensive way to identify food sensitivities is the "elimination-challenge" test. The suspect food is eliminated from the diet for a couple of weeks. If the symptom or symptoms improve, but the change is subtle, the food is re-introduced. An exacerbation of symptoms indicates food sensitivity.
This method is probably the "gold standard", but does have its limitations. When more than one food provokes symptoms, it may be hard to sort the sensitivities out. Or if other factors, such as stress or another change in diet enter the picture, the situation may become confusing.
Food sensitivities may also be identified through energetic testing. One method involves placing a food sample on or near the subject's body and testing for an autonomic nervous system response (e.g. change in strength of an indicator muscle or tone of an arterial pulse). Another technique measures change in electro-galvanic skin response at certain acupuncture points with the introduction of a test food into the body's magnetic field (electro dermal testing). These methods are controversial, and are not accepted by many in medical circles. One reason is that the science behind this testing is not fully understood. Another is that results seem to depend on the skill of the operator.
A third method of testing for food sensitivities is measurement of serum IgG or foecal (stool) IgA antibodies to specific foods. The foecal IgA method would seem to be a more direct measurement of reactivity for gastrointestinal disorders, and the serum IgG for systemic (body-wide) reactions. However, many in the medical community also consider these controversial, likely because no large-scale studies have been performed to assess their value.
Despite these limitations, these tests can be useful if their limitations are recognized. One principle to understand is that negative results can be false. In other words, very few antibodies to a food does not mean that the body will not react when exposed to that food. In fact, it is not unusual to see the antibody level to a certain food drop when the food is not ingested for a period of time. And then see the antibody level increase after re-introducing the food.
However, positive results can be very helpful. In other words, if a significant level of antibodies is found to a certain food, there is a good chance that that food is causing symptoms in the subject. This is especially helpful when a number of foods are causing reactions. When this is the case, removing these foods from the diet may eliminate or at least reduce symptoms.
After a rest period of a few months, the body may sometimes accept these foods, without reaction. It is always best to re-introduce such foods gradually. A "rotational diet", i.e. return of the food into the diet but only every few days is the safest way.
Once a food sensitivity has been identified, one might ask: What causes food sensitivities?
At least some of the answers lie in the small intestine and how it works. The small intestine is the biggest immune organ in the body. It also has its own nervous system - a system so large and complex that it has its own name: the mesenteric nervous system. The interior of the small intestine is a world of its own, a fluid environment filled with digested and partially undigested food, enzymes, bacteria, yeast and other microorganisms.
The small intestine is the part of the gastrointestinal tract that not only absorbs nutrients, but also rejects molecules that are not wanted. This is the job of the immune system (with the assistance of the nervous system). When the internal environment is healthy, it goes about its job without muss or fuss.
However, if this internal environment is disturbed, the immune system becomes irritable. It starts to react to foods it sees frequently, and even more so when these foods contain certain proteins such as those found in wheat or dairy products. This is why the most common food sensitivities in a western diet are to dairy, eggs and gluten, foods consumed by westerners on a daily basis. (Vegetarians typically develop sensitivities to other foods, reflecting what they eat most often.)
The internal environment can be disturbed by poor diet, poor stomach function, infections and a variety of drugs, the worst offenders being antibiotics, antacids, and anti-inflammatory medication. This is why food sensitivities generally do not appear by themselves. They usually are accompanied by other problems and often eliminating the offending foods alone is not enough to correct the situation.
Identifying and eliminating foods that cause sensitivity reactions can be very helpful in putting an end to unpleasant symptoms. However food sensitivity is usually found in combination with other medical problems and needs to be considered only part of a treatment plan.