Worldwide, the value of the nutrition and supplement market is estimated to be somewhere in the high tens of billions. That includes sports nutrition products like energy bars and various powders, as well as multivitamins and herbal supplements. It also includes a segment that is growing in popularity: food allergy and food tolerance tests.
One of the most popular tests available right now is an IgG (immunoglobulin G) test. It looks for antibodies in the blood that oppose certain food substances and it is often marketed as a way to identify hidden food sensitivities or intolerances. The test offers reports on multiple foods--often as many as 100 foods with a single panel test--and claims that removal of foods with high IgG levels can lead to improvement in multiple symptoms.
However, evidence shows that the IgG test (which is different from the IgE blood test) is more likely to indicate the foods we are often exposed to, commonly eat , and tolerate well. This is the opposite of sensitivity. IgG antibodies are produced by most of us in reaction to the foods we eat. In other words, the presence of food-specific IgG is a marker of food tolerance and exposure. Positive test results for food-specific IgG are to be expected in normal, healthy adults and children.
The science behind this, and other questionable tests has been discredited by medical groups around the world. Most major allergy and immunology organizations worldwide advise against IgG testing. As well as the costs of these tests (anywhere from $100 to $500) and the falsity of their quick-fix claims, they cite three main reasons:
1) The inappropriate use of these tests increases the likelihood of false diagnoses being made. It could also increase the likelihood of overlooking other conditions or factors that may have been the true cause of recognized symptoms.
2) These tests have mostly NOT been proved either scientifically or medically sound and may lead to unnecessary dietary restrictions and/or nutritional deficiency.
3) Consumers that receive results for a food intolerance test are often confused about the results and request additional referrals to see a specialist.
This is not to say that cutting certain foods won’t relieve people from bloating or dizziness. Instead, what experts agree on is that IgG food sensitivity testing is not reliable and will likely be a waste of time and money.
Worsening the controversy surrounding many of the available allergy and sensitivity tests is the media. Marketing and advertising around these tests tend to make no difference between the terms "allergy" and "sensitivity". In reality, they are very different--one is not a synonym for the other.
A food allergy is an immune-system response to food proteins. Typical food allergies involve the production of immunoglobulin E (igE) antibodies that are a part of our body’s immune system. Food allergy symptoms may include red eyes, an itchy rash, sneezing, a runny nose, shortness of breath, or swelling. Food allergies can be severe and in some cases life-threatening, so it is important to get an accurate diagnosis.
Diagnosing a food allergy is complicated. Only someone with proper training can obtain a detailed clinical history, conduct tests and interpret the results. Often, an allergist will survey a patient's medical history and perform both a skin-prick test and an immunoglobulin E (IgE) blood test. A skin-prick test involves a teeny puncture on the skin and the application of a diluted allergen. If the patient is allergic to the substance the puncture will turn red and itchy after roughly 15 minutes.
However, both skin and blood IgE tests have high rates of false-positive results. This is one of the reasons why diagnosing food allergies is complicated and requires a specialist with proper training. Results need to be interpreted in the proper clinical context alongside a full understanding of what symptoms occur when a particular food is ingested. In other words, the tests are reliable, but only when used appropriately and interpreted in the proper context.
A food sensitivity, or intolerance, involves adverse reactions to foods that do not include an autoimmune response. Metabolic disorders, nausea, inhibition of regular digestive function and other responses to active food components are considered a “food intolerance” or “food sensitivity”. As you can see, it is a broad term used to describe foods that the body has difficulty tolerating.
Food sensitivity reactions can take hours or even days to develop. This makes pinpointing them challenging and means that no blood test is validated for the diagnosis of food intolerance. As a general rule, people who experience gastrointestinal symptoms after eating should see a doctor or dietitian to help them identify the trigger food. Often these specialists recommend an elimination diet, where patients stop eating certain types of potentially problematic foods, then reintroduce them one at a time. This helps to zero in on the food that might be causing digestive issues.
As consumers, we are bombarded with health information and dietary advice from all directions. However, not all of this information is true or science-based, and not everyone is a trusted authority.
If you suspect a severe food allergy or a major food sensitivity, or are experiencing digestive symptoms like abdominal pain, bloating and change in bowel movements, don’t self-diagnose or use test kits. Food allergies are very serious and the first step should be to get an assessment by a trained medical professional.
Alternatively, if you have no major issues but still suspect you react to some foods better than others, then a good option is to start a food journal. Journaling your dietary habits will help make sense of the links between food, energy, mood, and performance. Best of all, it requires no additions or restrictions, and it will make a specialist's job much easier should you choose to visit one in the near future.