Food sensitivity testing has grown in popularity in recent years as more and more people realize that their diet can contribute to their chronic symptoms, but is food sensitivity testing worth it?
Before getting into the usefulness of food sensitivity testing, it is important to understand the difference between food sensitivities and food allergies.
Food Allergy vs Food Sensitivity
Food allergies are abnormal immune reactions to proteins in food [1]. Some of the most common foods that provoke allergic symptoms in certain predisposed people include eggs, dairy, peanuts, tree nuts, soy, wheat, fish, and shellfish [2]. Food allergies occur when immune cells make antibodies, known as immunoglobulin E (IgE) antibodies, that respond to certain foods. IgE antibodies bind to certain immune cells, and when a food is eaten that the IgE antibodies are reactive to, a release of chemicals is triggered from the immune cells and this causes allergic symptoms. The timing and severity of these symptoms is key in distinguishing a food allergy from a food sensitivity.
Food allergy symptoms usually occur just minutes to hours after someone eats a food they are allergic to, and allergic symptoms can sometimes be life-threatening. Allergic symptoms may include things such as a runny or itchy nose, sneezing, skin rash, swelling, difficulty breathing, wheezing, abdominal pain, diarrhea, and vomiting [1]. In contrast to this, food sensitivities are thought to result in more delayed symptoms that can occur several days after eating an offending food. These symptoms are usually less sudden and severe, and may include things such as abdominal pain, bloating, diarrhea, constipation, fatigue, headaches, and brain fog. Food sensitivities are thought to involve IgG antibodies rather than the previously mentioned IgE antibodies associated with allergic reactions.
The delay in symptoms associated with food sensitivities makes it more difficult to identify which foods may be at fault. For example, if a person with a suspected food sensitivity experienced brain fog and abdominal pain after eating wheat three days ago and cow’s milk two days ago, it can be challenging to figure out which food is to blame. Or did both foods lead to the symptoms? This is where food sensitivity testing comes in. Food sensitivity tests usually involve testing the blood for elevated levels of IgG antibodies to commonly eaten foods [5], then advice is typically given to patients recommending they avoid foods that provoke strong IgG responses.
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The Problem with Food Sensitivity Tests
Assessing food sensitivities based on IgG levels seems to make sense from a logical standpoint. After all, IgG antibodies are instrumental in protecting the body from pathogens such as bacteria and viruses [6], so it would seem to make sense that increased IgG levels to a particular food would indicate that that food is a threat to the immune system. However, the immune system is highly complex, and the best available scientific evidence indicates that elevated IgG levels towards food is not only NOT a problem, it is actually NORMAL [7].
About 70-80% of all immune cells in the body are located in the intestines, and these immune cells are tasked with determining if food components are dangerous or harmless [8]. If a food is deemed potentially harmful by the immune system, a protective response will be initiated such as in food allergies. However, even if a food does not appear to be a threat to the immune system, there will still be an immune response, and this response involves IgG antibodies.
Research has shown that IgG reactions to a particular food may simply indicate repeated exposure to that food [7]. Additionally, increased IgG levels to food occurs in perfectly healthy people. This was seen in one study where IgG levels in people with irritable bowel syndrome (IBS) were compared to people with indigestion and healthy people. The IBS group tended to have a greater IgG response to certain foods, however all three groups had elevations in IgG and there was no correlation between IgG levels and symptoms [9].
Organizations that recommend against IgG testing for food-related complaints [7]:
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A 2019 study echoed these findings when it was shown that 42% of healthy, asymptomatic people had increased IgG to certain foods, including corn, egg, milk, rice, soybean, tomato, mushroom, and codfish [10]. In the study, IgG levels did not differ significantly between healthy people and people with ulcerative colitis, a type of inflammatory bowel disease.
These studies demonstrate that food sensitivity tests do not accurately distinguish a healthy person from someone with chronic gastrointestinal issues. This calls into question whether food sensitivity tests provide any useful clinical information. This, along with the fact that food sensitivity tests can cost hundreds of dollars suggests that avoidance of these tests may be the best option.
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Alternatives to Food Sensitivity Testing
If you are someone who experiences symptoms after you eat certain foods, or you suspect that food could be contributing to your symptoms, there are other options for you rather than paying for a food sensitivity test.
One option is to temporarily undergo a diet that restricts commonly problematic foods. This type of diet is known as an elimination diet. Elimination diets involve the removal and careful reintroduction of foods to help identify specific trigger foods and improve symptoms. There are a number of different elimination diets and they all vary in how many foods are eliminated. Some examples of elimination-type diets that have been shown to improve health include a Paleo diet, Autoimmune paleo diet, low FODMAP diet, and a low histamine diet [11, 12, 13, 14].
Another option that goes hand-in-hand with an elimination diet is addressing the health of your gut. As mentioned above, most of the immune system is located in the gut [8], and poor gut health can be a major driver of inflammation. Inflammation can lead to leaky gut (also known as intestinal hyperpermeability), which occurs when the gaps between intestinal cells become too wide [15]. When leaky gut is present, food components and gut bacteria are able to pass through the lining of the intestines and into the blood, further driving inflammatory processes. An inflammatory gut environment may also be the result of dysbiosis, which is an imbalance between pro-inflammatory and anti-inflammatory bacteria [16], and this can contribute to symptoms as well.
Some factors that can help you address the health of your gut include the previously mentioned elimination-type diets, probiotics [17], digestive enzymes [18], and nutrients such as vitamin D and glutamine [19, 20].
Overall, IgG food sensitivity tests currently lack validity and there is no evidence that they are beneficial for food sensitivities or food allergies [21]. It is possible that eliminating foods based on IgG test results can improve symptoms. However, if this occurs it is likely due to the removal of foods that would have been excluded on an elimination-type diet anyway. So you can save yourself the hassle of getting one of these tests and rest easy knowing that you have other options.
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If you are experiencing symptoms and would like guidance in implementing any of the above mentioned dietary changes, SunCoast Functional Medicine can provide you with the necessary support and expertise to help you improve your health. Feel free to reach out and apply to become a patient.