What is the Difference Between a Food Allergy, Food Sensitivity and Food Intolerance? And What are the Best Tests?

Many of my patients ask me about food allergies and what the best tests are. I thought I'd write an article to clarify. There has been a sharp rise in food allergies and I've noticed many urban restaurants now have gluten free options. Servers will often ask a party if there are any food allergies before taking orders. More people are much more conscious of food sensitivities. In fact, there are studies showing links between food sensitivities and difficulty losing weight, autoimmune diseases, and gastrointestinal diseases. Some patients achieve some type of relief by avoiding certain foods.

However, I've seen patients who are so sensitive that the list of foods they can tolerate is so small, that their quality of life does not seem so fun. I feel it is important to identify food sensitivities and avoid them for a period of time to allow the body to calm down. I do not feel that it is optimal for a person to be permanently "allergic" to say 50% of all foods tested. This often means that there may be intestinal permeability issues that allow too much exposure of food antigens to the immune system. In these cases, it is very important to also work on improving intestinal health as well as immune modulation in addition to working with food allergies.

More information on food allergies, sensitivities, intolerances and testing options are below.

Food Allergies:

IgE Food allergies occur when the immune system makes antibodies to foods. This is a very specific reaction like a lock and key. If the antibodies made are IgE antibodies, the reaction is usually immediate. These reactions can be immediate fatigue, immediate hyperactivity, swollen lips, abdominal discomfort and respiratory symptoms. An IgE mediated reaction is what we classically call a food allergy. Usually anaphylactic reactions fall into this category.

If the antibodies produced are predominantly IgG antibodies, the reaction is often delayed sometimes 24-48 hours after eating the offending food, making it more difficult to pinpoint a correlation. Sometimes the symptoms that show up may be subtler, such as poor concentration, chronic respiratory symptoms, chronic behavioral issues, and frequent illness.  These non-distinct reactions make it difficult for people to realize that they have a food allergy but knowledge of this can be very helpful. For example, people with chronic diseases such as autoimmune diseases, chronic pain and inflammation, allergies, asthma, headaches, itching and fatigue tend to have underlying food allergies.

Food Intolerances:

Food intolerances occur when the body lacks enzymes to digest a certain type of food. A classic example of an intolerance is lactose intolerance, where an individual lacks the enzyme lactase that breaks down lactose, a sugar found in dairy products. Thus people with lactose intolerance usually will have symptoms such as abdominal pain, flatulence, diarrhea or fatigue when consuming milk products. A lactose intolerant individual may also have an allergy to milk in addition to the intolerance. People who have an intolerance often feel better by avoiding the food, but in mild cases can consume the food with a digestive enzyme given to help the body break down the food.

Food Sensitivities

This is a non-specific immune response to food. For example, white blood cells may swell, change morphology, or rupture in response to exposure offending agent. This is not an allergy because an antibody is not produced. These reactions are often harder to identify and may be an underlying problem contributing to weight problems, chronic disease, behavioral issues to name a few. These types of sensitivities often show up with an ALCAT testing when a skin prick test or RAST test is negative. 

Testing:

Skin prick allergy tests usually measure IgE antibodies. They are very good for detecting environmental allergens and some food allergies that tend to be more severe such as peanut allergies. Skin prick tests are generally not good tests to test for foods because they often show false negative results. A RAST test is a blood IgE test that may be more accurate for foods than a skin test.

IgG blood tests give some additional insight and show allergies that are subtler and delayed. These reactions still trigger an inflammatory response that is usually not as acute or obvious. But this chronic low-grade inflammation can be enough to release enough inflammatory chemicals that can cause more oxidative damage to the body.

The gold standard for finding problematic foods is the elimination challenge test. Patients restricted to 4 non-allergenic foods for 2 weeks, then re-introduced one food at a time and monitored for reactions. Data shows this is more accurate than any of the laboratory tests. However, this is often difficult to do and very labor intensive.

ALCAT Laboratories offers a blood test that measure the change in size of white blood cells when exposed to certain foods, thus measuring the immune reaction to the food, rather than anti-bodies. The immune system can react to what it perceives as an intruder without making antibodies. This test is personally my favorite test and seems to be much more clinically relevant than the RAST test. A study done at the Department of Pediatrics in Pavia Italy showed that patients with gastrointestinal symptoms who tested negative for allergies (skin prick, and RAST), when following the ALCAT food elimination had improvements in their symptoms. ALCAT tests picked up what some of the other tests did not. Another study showed that patients who were unable to lose weight on a low calorie diet, who followed the diet plans according to their individualized ALCAT tests observed significant decrease in body weight according to the Middle East Journal of Family Medicine. Lastly according to the Medical School of Cape Town Africa, ALCAT testis high a high degree of reproducibility.

Some doctors such as myself will also use kinesiology or muscle testing in addition to the blood tests. I sometimes find that muscle testing gives more accurate results than any one of these blood tests used alone, and I postulate that muscle testing combines all types of reactions the body has to the food, as we attempt to energetically get information from the body.

According to Dr. Mark Hyman MD, these are symptoms to look for if you suspect a reaction to certain foods. Many of these symptoms are generally not thought of in relation to a food, but can be a tell tail sign that there may be some benefit to finding out if you have any food sensitivities or intolerances. Many of these symptoms are vague and may be associated with other medical conditions as well, so consult your health care provider. 

Brain fog	Cough	Pain
Depression	Headache	Fatigue
Anxiety	Sleep problems	Changes in skin (acne, eczema, rash)
Anger	Joint/Muscle aches	Changes in digestion or bowel function
Hyperactivity	Respiratory congestion	Difficulty remembering things