For years when new patients came to my clinical nutrition practice and filled out paperwork that asked them to list their food allergies or intolerances, their answers were predictable and understandable. They’d often list foods like peanuts or shellfish, which are among the top eight food allergens in the U.S. and represent the allergies least likely to be outgrown after childhood. In the spring and fall allergy seasons, patients would frequently list foods like raw apples, peaches or carrots, which commonly cause itchy mouth or throat in people with severe pollen allergies — a common condition called oral allergy syndrome. Finally, I’d see dairy or lactose listed pretty often, which made perfect sense to me as a clinician working in a racially and ethnically diverse place like New York City: the majority of the world’s non-European/Caucasian population develops lactose intolerance at some point before adulthood.
[See: 8 Dairy-Free Desserts.]
But about five years ago, these lists began growing longer and more specific — and making less and less sense. First, new patients started routinely arriving with a self-reported gluten intolerance. Then, they began arriving with lists including specific types of refined plant oils like canola or safflower; specific species of finfish like tilapia, but not sole; certain plant members of one botanical family, but not others (broccoli, but not cauliflower); or certain types of mammalian (red) meat, but not others.
What’s going on? It’s all traceable to an explosion of “food sensitivity” tests, or blood tests that purport to measure non-allergic, but supposedly inflammatory, reactions to a variety of foods. (I won’t name names, but if your lab result printout is in full color or is based on “IgG” antibodies, then you’ve encountered such a test.) Gluten, dairy, corn and soy are always included on these lists. In fact, I’ve never seen a food sensitivity test result that didn’t include them as ingredients to be avoided. Understandably, patients who’ve undergone these tests come to me in a state of confusion bordering on panic: Now that they’ve been “diagnosed” with literally dozens of food sensitivities, how are they supposed to navigate eating?
The answer is not to starve; it’s to question these tests. None of them have been scientifically validated to diagnose anything, which is why insurance doesn’t cover them. (I’ve seen patients spend well over $1,000 on these unproven tests.) Many such tests measure levels of an antibody called IgG, which research shows is actually a mark of food tolerance — not intolerance! Other types of proprietary tests hide behind the pretext of “trade secret” equipment and methodologies to examine blood samples for supposed food sensitivities. In other words, the scientific community cannot vet and validate their results to see whether they are biologically plausible and would hold up in blind, controlled challenges.
To be sure, food intolerances do exist. Here are some of the most common ones I see — none of which, by the way, are diagnosable by blood test:
— Enzyme Deficiencies: Some adverse digestive reactions are due to enzyme deficiencies, like lactose intolerance or discomfort related to eating high-FODMAP foods, including certain wheat-based foods. In fact, enzyme deficiencies may explain why so many people feel better on gluten-free diets. Recent double-blind, randomized controlled trials have suggested that the vast majority of people who believe themselves to be “gluten intolerant” — somewhere between 60 and 95 percent, depending on the study — are actually reacting to a carbohydrate in wheat called a fructan that we humans lack enzymes to digest. (Some gluten-rich foods like sourdough bread are low in fructans and are well-tolerated by most people with suspected gluten sensitivity.) There are some commercially available enzyme supplements that can improve tolerance of certain such foods (think lactase for dairy intolerance). But no enzyme supplements are available (yet) to aid in digestion of foods containing fructans.
[See: Foods That Cause Bloating.]
— Pharmacological Reactions: Some food intolerances result from a biochemical reaction to specific compounds in a food or beverage — not unlike how one might react to a drug. These compounds’ presence in a food often depend on the method of processing, food additives or the food’s age.
— Histamines: Histamine is a signaling molecule that’s derived from a protein component called histidine, often as the result of aging or bacterial fermentation. Some people — particularly those with a strong history of environmental allergies — can be especially reactive to foods high in histamine, and consuming them can trigger a range of symptoms that may include rashes, hives, rapid heartbeat, “brain fog,” bloating, diarrhea and acid reflux. The severity of the reaction may vary based on how much of the food you consume and how high the burden of environmental allergens is at the time of eating, making it tricky to nail down the cause without the help of a trained dietitian.
— Tyramine: Like histamine, tyramine is a molecule derived from a protein component and can be high in aged and fermented foods. For some people, high tyramine foods trigger migraines. Those who use medications called MAO inhibitors can experience an acute and dangerous spike in blood pressure related to consuming tyramine-rich foods.
— Sulfites: Sulfites are food additives commonly used as preservatives in wine, dry fruit, processed fruit juices, frozen shellfish, processed potatoes and condiments. They can trigger asthma attacks in asthmatic people, or allergic-type symptoms like abdominal pain, diarrhea, nausea, vomiting, wheezing, hives, facial swelling or flushing in otherwise sensitive individuals.
[See: 8 Surprising Facts About Asthma and Seasonal Allergies.]
Don’t waste your money on unproven “food sensitivity” testing. Instead, maintain a record of the food(s) or dishes that seem to have provoked symptoms for you in the past. Include specifics, too, about the type of reaction you had and the time frame in which it occurred. Bringing such a list to a credentialed registered dietitian or allergist/immunologist may help you identify the true culprits behind your mysterious food reactions.
More from U.S. News
How to Survive Ragweed Allergy Season
6 Common Indoor Allergy Triggers and How to Avoid Them
Pharmacist Recommended Cough, Cold and Allergy Medicines
Should You Get Tested for Food Sensitivities? originally appeared on usnews.com
