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What's Really Making You Sick?

New Blood Test Can Uncover the Real Cause of Your Symptoms

September 2010

By Lauren Russel, ND, and Jonathan V. Wright, MD

Inconvenient and Expensive Test Methods

Inconvenient and Expensive Test Methods

Diagnosis of a food sensitivity depends on many things, including your previous medical history, comprehensive physical examination, oral food challenges, and results of laboratory testing.7,29,30 There are several types of laboratory tests designed to detect food allergies and sensitivities. One of the best known allergy tests measures for food-specific IgE antibodies using a skin prick test, in which the patient is exposed to a variety of foods scratched into the skin and observed for a local allergic reaction. Although fairly accurate for inhalant allergies, the positive predictive accuracy of skin prick tests for food allergens is less than 50% compared to double-blind, placebo-controlled food challenges.31

There are two types of skin testing that may be far more accurate, but they take considerably more time. Performed almost exclusively by physician-members of the American Academy of Environmental Medicine (, they’re termed “provocation-neutralization” and “serial dilution titration.” In addition to accurate testing, these techniques can help you identify and resolve your food sensitivity issues.

The “radioallergosorbent” test (RAST) and its successor, the “enzyme-linked immunoassay” (ELISA) are both blood tests used to detect food-specific IgE and/or IgG responses. Most commonly, food sensitivities are assessed using the ELISA test to detect IgG4 antibodies to food antigens, a subclass of IgG antibodies. Between 45 and 95 separate foods are measured. Accurate testing requires the patient to eat a wide range of foods within 3 weeks of assessment for IgG4 exposure to be present.

A Cutting-Edge Detection Method

Fortunately, an advance in diagnostic technology is now available that uses a very small amount of your blood to assess your sensitivity to 45 of the most common food antigens. Instead of requiring blood to be drawn from a vein, a small lancet is used to prick the finger so that a few drops of blood can be placed on a blood spot collection card. After the card is allowed to air dry, it is returned to the laboratory for assessment of IgG4 antibodies to food.

Known as the FoodSafe™ test, this is a simple and effective way for you and your doctor to detect the foods your body can’t handle. Each test report comes with a personalized profile showing how you tested against 45 foods most commonly associated with food sensitivities. The report indicates whether the levels of antibodies to the various foods suggest they are “safe” to eat, best to eat in moderation, or foods you should avoid entirely. Results are ranked and reported to you and your doctor as either safe or not safe.

After reviewing your test results, you may wonder what’s left for you to eat, since it’s not uncommon for many of the foods causing you the most trouble to be your favorite foods. Although each person’s plan may vary, more than likely your doctor will ask you to avoid the foods that are considered “unsafe” on your test results. Generally, this means going on an elimination diet for up to 30 days, during which time you avoid the foods that you are most reactive to in your profile. It’s a good idea to also avoid foods that are from the same “family” as those foods you are reactive to. For example, sensitivity to one kind of shellfish may mean that you should avoid other types of shellfish for a certain length of time. For this reason, your doctor may prescribe a diet that contains foods less likely to trigger reactions and allows your body and gastrointestinal tract time to recover from the continuous assault it has unknowingly experienced.

A Cutting-Edge Detection Method

Does this mean you will never be able to eat these foods again? The answer depends on your problem foods and your symptoms. Obviously, if your allergic reaction is life-threatening, you’ll be advised to permanently avoid that food. There are other reasons for life-long avoidance, too, such as gluten intolerance, which makes absorption of many nutrients difficult and good health impossible.

In other cases, you may be able to add a food back into your diet after a period of avoidance, as long as you eat it less frequently. One approach is to avoid the “reactive” foods for a period of time specified by your physician, typically 2 to 4 weeks, and then re-introduce these foods back into your diet to see if you respond to them.32

When avoiding foods during trial periods, eliminate even very small amounts! Reading food labels and understanding the many ways foods are listed as ingredients is important. By avoiding foods for this length of time, your body and immune system have time to recover, and you’ll have a more accurate idea about whether the food can be re-introduced or not, and if so, how often.

During the “challenge” (re-introduction) phase of the elimination diet trial, your doctor may ask you to re-introduce one food that you were reactive to once every 4 days to see if symptoms recur. If you don’t develop symptoms, then it may be possible to include the food in your diet, but less frequently. If symptoms do recur, then you may have to avoid the food for 6 months or longer.

Rotation diets have been shown to be very effective for treating food sensitivities in some people.33 On the rotation diet, a food is only eaten once every 4 days, allowing the body to clear it between exposures. The rotation diet helps you avoid too much exposure to any one food and gives you a better idea what foods are contributing to your symptoms, in case they recur. If you are more sensitive to certain foods or clear them more slowly from the body, you may need to eat them no more frequently than once every 7-10 days.

Your plan may also include taking omega-3 fatty acids to lessen inflammation, probiotics to replenish gastrointestinal flora, and other products like glutamine that promote intestinal healing.9,34-36 One of the primary benefits of food sensitivity testing is that your doctor can more easily customize your approach based upon your history and test results.


An estimated 45-60% of the general population suffers from serious symptoms and health conditions whose causes cannot be identified. Many of them have no idea that various forms of food sensitivity may be to blame. Reactions to food are the hidden cause behind an extraordinary array of health problems, including headaches and migraines, insomnia, and digestive disorders. An advanced, convenient diagnostic blood test technology called the FoodSafe™ test now enables you and your doctor to zero in on the potential foods behind your health problems and methodically eliminate them—for lifelong relief and optimal health.

If you have any questions on the scientific content of this article, please call a Life Extension® Health Advisor at 1-866-864-3027.


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