By Mary Carpenter
THE LATEST self-tests that claim to detect “food intolerances”— to proteins, grains, fruits, vegetables, seafood, gluten, additives and preservatives—boast of relieving low-level chronic health complaints, such as digestive issues and fatigue. While most self-tests rely on blood and urine samples, “5Strands,” which costs as low as $50, offers “bioresonance” analysis of hair (five strands) to assess energy patterns and wavelengths for indications of reactions to about 600 food and beverage ingredients.
The accuracy and usefulness of self-tests, including those based on blood and urine samples, are in question, however, as is their vocabulary: “intolerances,” “sensitivities” and “allergies” to food. The only accepted diagnosis of digestive issues related to gluten is celiac disease—not an intolerance or sensitivity but an autoimmune disease —which requires a gut biopsy for the final determination.
As for 5Strands detecting energy patterns and wave lengths in a body’s response food, the American Academy of Allergy, Asthma, and Immunology told the “Today” show there is “no scientific evidence.” Also, biologic reactions to food ingredients depend on a host of factors and vary widely among individuals, making it difficult to establish the population-wide reference levels on which self-tests rely; and documenting any link of health improvements to the elimination of any specific food ingredients requires very large studies lasting over months or years.
Hair sample testing has, however, led to successful treatment of patients in alternative and functional medicine practices, for complaints of chronic, low-level health issues that have not been addressed or taken seriously by traditional health-care practitioners. By itself, however, close attention to an individual’s difficulties can lead to improved health, as can encouragement for anyone to pay greater attention to diet.
For DNAweekly reviewer Sara Turner, 5Strands testing detected a high intolerance to dairy products and beef, which she eliminated and afterwards “felt better”—leading to her enthusiasm for finding “a diet that lets me consume bacon, alcohol and noodles!” On the other hand, Turner pointed out that, despite personal experience with data analysis, it took more than five hours for her to make sense of the results —provided in long lists of obscure chemical ingredients.
Fatigue, aches and brain fog lifted “almost immediately,” Seattle hiking supply store owner Kristi Wood told the New York Times, based on InsideTracker blood testing that showed excessive levels of Vitamin D and led her to stop taking the supplements. And for ex-Army ranger Joseph Roberts, InsideTracker results prodded him to make changes, such as cutting back on the energy drinks responsible for his elevated vitamin B12 level—and he proclaimed the test “life-changing.”
An evaluation of 1,032 individuals using InsideTracker focused on vitamin D and LDL cholesterol—both having “important implications for a spectrum of health-related physiological processes,” according to Tufts University researchers. Vitamin D has correlated, for example, with nutrient intake and lipid metabolism; and LDL with iron storage and electrolyte status.
Interventions leading to healthier levels of both—and consequently to improvements in related biomarkers — included increasing vitamin D supplements; and, for LDL cholesterol, adding oats, green tea and dairy products to the diet. But researchers cautioned that improvements could result simply from information about “problematic biomarkers inspiring lifestyle changes independent of any recommendations received,” and that their analysis was observational and meant for “hypothesis generation only.”
For diet-related health problems, most self-test blood measurements assess levels of immunoglobulin G (IgG) antibodies —which are one element in a body’s immune reaction but are unreliable because they fluctuate daily depending on recent food consumption. More importantly, different, IgE, antibodies are the ones involved in true allergic reactions—and these vary so widely among individuals that it’s impossible to depend on single reference levels used in self-testing results.
But unreliable vocabulary may be indicative of the most undermining problems of self-testing—notably “food intolerance,” which most products use interchangeably with “food allergy” and “food sensitivity.” Unlike food allergies, which are related to the immune system, food intolerance arises from the lack of a specific enzyme required for digestion— as with lactose intolerance—which are not assessed by self-tests and are often accompanied by other factors that are difficult to test for.
As for “food sensitivities,” one review from a generally reliable site notes that these “are caused by an immune reaction driven by antibodies such as immunoglobulin G” and others, but never mentions the true food-related antibodies, IgE. Also the review includes such disclaimers as “some studies suggest that the presence of these antibodies may not be an accurate or reliable marker of a food sensitivity”; and “at-home food sensitivity tests are not recommended for diagnosing food sensitivities.”
And despite the review’s focus on food sensitivities, there is no mention of these for “Best at-home food intolerance test” (FoodMarble AIR) or “Best at-home food allergy test” (Labcorp food allergy test). Yet, included under a third category —Best if you already took a DNA test” (Vitagene), which “tests your DNA to see how your genetics influence your health” — is the disclaimer that “it is not possible to identify food sensitivities based on your genetics.”
“Omics” —global analysis techniques—might, on the other hand, in the future help create “precision nutrition,” based on an individual’s DNA along with such influences as environment, nutrition and lifestyle exposures. But, according to Spanish and Dutch researchers, “we are still far from being able to define and use” the iPop (integrated personal omic profile) as a preventive and diagnostic tool.
While self-testing is tempting as a way to inspire more careful attention to my diet, especially trial eliminations, such as dairy foods linked to inflammation and arthritis pain, which people constantly recommend I avoid. But because my salient food issues are not sensitivities but are instead related to the mechanics of digestion, I already avoid enough foods that are notoriously difficult to digest including beans, nuts and whole grains—even popcorn—and for now that’s the most attention I can devote to diet.
—Mary Carpenter regularly reports on need-to-know topics in health and medicine.