Food Intolerance Tests Are Shoddy Science and Traps for Disordered Eating
Trendy food intolerance tests aren't accurate, but they fuel our obsession with what we can and cannot eat.
I promised myself that on the day I wrote this article, I would eat oatmeal for breakfast with peanut and almond butter on top. Those are three foods that an at-home food intolerance test, Pinnertest, suggested I give up almost a year ago, and I’ve been struggling since to reintroduce them into my diet.
I first encountered Pinnertest while scrolling through Instagram. It was being marketed by health and wellness influencers, and many celebrities have lent their faces and accounts to the test as well. Other food intolerance tests have recently popped up too; one called Everlywell started showing up in my feed alongside perfectly plated food, manicured nails, and an assurance that a simple blood prick could easily tell you what foods were causing your stomach upset.
Yet scientists and allergists say that the science behind these tests is shaky at best, and completely misleading at worst. While they’re being promoted through attractive filters online, the people who take them are left with long lists of foods that they’re supposed to eliminate and confusion about what a food intolerance really is. Take me, for instance: I don’t think I’m actually intolerant to the foods from my results.
But getting test results that showed that my immune system had made an antibody called Immunoglobulin G, or IgG, in response to peanuts, oats, almonds, and egg whites, it was hard not to feel wary of those foods. And so, I’m ashamed to say, I still didn’t eat oatmeal for breakfast.
This is the true danger of these tests: not just that they could be incorrect, or have kept me from PB&Js for a whole year, but that they can be a sand trap for anyone with disordered thoughts and fears around eating.
Am I ever going to eat an oatmeal raisin cookie again?
A food intolerance is not the same thing as a food allergy. Allergies are a specific adverse reaction to a substance, which can be food, medicine, or venom, and they can be life threatening (think: kid you went to elementary school with who always carried an Epi-pen). If you’re genetically predisposed to be allergic to a food, when you encounter it, your immune system produces Immunoglobulin E, or IgE, antibodies, which travel to cells that release chemicals that cause the allergic reaction: itchiness or tightness in the throat, nose, mouth and airways. In severe cases, anaphylaxis can occur.
Food intolerances have a murkier definition. They’re described by the American Academy of Allergy Asthma and Immunology as “when a person has difficulty digesting a particular food.” The symptoms are mostly stomach-related, like intestinal gas, abdominal pain or diarrhea. But migraines, fatigue, eczema, and head fog have also been attributed to food intolerances. A basic way the AAAAI differentiates the two is that food intolerances involve the digestive system and food allergies involve the immune system. But wait, food intolerance tests, like Pinnertest and Everlywell, also look for an antibody: IgG.
It’s been a long debate as to whether IgG antibodies, a different kind antibody than IgE, have anything to do with predicting food intolerances. I asked Robert Hamilton, a professor of medicine at Johns Hopkins University who runs a diagnostic allergy laboratory, what the deal was. He didn’t his mince words: “There is no firm, peer reviewed data that verifies that IgG antibody is diagnostically useful,” he tells me. “This type of food sensitivity test is essentially a bogus test.” He says that the presence of IgG antibodies for a certain food in my blood could merely mean I was recently exposed to it, not that I was sensitive in any way.
That rang true for me: A couple weeks ago, I also took an Everlywell test to compare the results to my Pinnertest. A whole bunch of new foods had popped up, including walnuts, sunflower seeds, and cashews. Those were foods I only started to eat a lot of after my Pinnertest eliminations (walnuts and sunflower seeds in place of almonds and peanuts). The fact that I had IgG antibodies in my blood could be telling me what I already know: I'm eating these foods regularly.
“But it doesn’t mean that you are sensitive or intolerant to those,” Hamilton says. “And it certainly doesn’t mean you should avoid exposure to them, or avoid eating them. This type of test is basically totally inappropriate. And how it can get on the market, and be sold, with these claims, is very disturbing.”
All the food intolerance tests are considered “laboratory-developed tests, and are therefore not regulated by the Food and Drug Administration,” StatNews recently reported. And despite who’s vetting them, they’re selling well. Everlywell recently received a one million dollar investment from Shark Tank, and raked in $6 million in sales last year, Stat wrote. Everlywell also sells other at-home medical tests, but their food intolerance test is the best-seller. It costs $199 and Pinnertest costs $490; Everlywell screens for 96 common foods, while Pinnertest screens for 200. If you read the fine print, both tests say that their results are just meant to be a "guide" for elimination, not a definitive diagnosis. But even that, Hamilton says, reaches beyond what IgG antibodies can tell us.
“We’ve been fighting this for many years," Hamilton says. "I’m a firm believer in the lack of utility of this kind of antibody test in predicting or identifying food intolerance. All of our professional allergy societies, immunology societies, back that statement up with policies that they have.” AAAAI, which is the professional society in the United States, has a position statement on this issue, as do the Canadian Society of Allergy and Clinical Immunology and the European Academy: All say that IgG tests should not be used to diagnose food intolerance.
When I contacted Everlywell to ask about the validity of their test, a spokesperson replied saying the following: “We believe there is a divergence of views regarding IgG tests. We recognize that the AAAAI does not support any form of food sensitivity testing (which is not just limited to IgG testing), but they are not the entire 'medical community,' and AAAAI does not speak for all health care providers."
Hamilton thinks that food intolerances can be very real. But to identify those intolerances, you need to do a good old-fashioned elimination diet, which involves taking out the top food allergens, keeping a food diary, and consulting with an allergist or dietician. You could also do blind placebo exposures on yourself, with potentially troubling food. “Those and elimination diets are very tough to do and tough to interpret,” Hamilton says. “And for that reason, a lot of people fail at those types of tests and they want a quick and dirty way of assessing what they should avoid.”
At the root of an elimination diet there is a hope that some larger problem will be magically resolved. I was pretty vulnerable when I first saw Pinnertest as I was scrolling through Instagram. I had been traveling a lot for work, was finally settling back into my apartment and city, and my usually manageable OCD came out to play in a big way.
I have health and contamination phobias and obsessions, so the idea of getting a list of the foods that were contaminating me, to resolve vague (and probable anxiety-related) physical symptoms was appealing. I did research IgG antibodies before I ordered the test, and came across all the research saying it wasn’t legit. Here’s the thing: I didn’t care.
The problem with these tests isn’t that the truth is being hidden from consumers, it’s that: if you are struggling with any kind of disordered eating or thinking patterns, you will latch onto them despite what the evidence says. When I joined the Everlywell Facebook group, I saw a lot of posts from people who were confused at how some of their most frequently eaten foods showed up, and stressed at how to eliminate sometimes five to ten or more foods at the same time. I won’t quote any of their comments here because it’s a private group, but I saw a lot of myself in their worries.
Because of my OCD, I also love rules, and once I implement a rule, it’s extremely difficult for me to break it, as it becomes a ritual. As last year went on, and I got my anxiety under control again, I still couldn’t manage to eat those foods.
My specific mental trappings might be a bit unique, but Hamilton says that he’s heard of many people using the elimination foods as an excuse to restrict more, and lose more weight. People with anorexia or orthorexia—the obsession with healthy and clean eating—are especially at risk.
On the Facebook group, you can also find people who said they their symptoms–wide ranging in nature–improved as the result of cutting out foods. Everlywell directed me to a webpage filled with testimonials from people who eliminated foods and ended up feeling better.
Maybe some people happened upon the food they really did have an intolerance to; it’s not impossible. But for others, it could all be wrapped up in how much influence our minds, expectations, and fears have on our eating. The same reasons I couldn't bring myself to eat oatmeal.
I got in touch with Emeran Mayer, who is the director of the Oppenheimer Center for Neurobiology of Stress Ingestive Behavior and Obesity Program at the David Geffen School of Medicine at UCLA. He treats patients with GI issues, like irritable bowel syndrome and disorder, but tells me that most of his patients who have encountered these intolerance tests have what's called "functional GI disorder"—when a person has continuing symptoms but no definitive diagnosis.
He thinks everyone is vulnerable to the underlying mental booby traps these tests put out there: The idea that there are foods, healthy foods, that are secretly making you sick. The anxiety such a thing creates is not benign, he says. While a placebo effect could make some people get better from cutting out pineapple or green peas, such an effect could just as easily be contributing to upset stomachs, causing the very symptoms people are trying to avoid. Mayer also studies the interaction of the gut and the brain; he recently wrote a book called The Mind-Gut Connection.
He tells me that when people have extreme anxiety, the brain generates stress signals that travel to the gastrointestinal tract through the autonomic nervous system and the vagus nerve. This stress can change a lot of aspects of the gut and digestion. It can alter transit time of food through the digestive system, it can change blood flow or immune responses, it can change secretion of mucus, and all of those changes can then affect the bacteria that live in your gut, or your microbiome.
“If you’re walking around being stressed around your food and being constantly worried, that is becoming kind of a self-fulfilling prophecy from the nocebo effect," he says. (The nocebo effect is when the suggestion of negative effects might actually bring about those negative effects.) "But also it changes your gut-environment context in a way that can compromise the proper digestion of food. There’s a really close link between anxieties, food-related stress, and gut dysfunction.”
Whenever I sat down to try to reintroduce a food from my elimination list, I would wait nervously for the backlash. I began to pay way too much attention to my stomach, and how it was feeling. That negative expectation, according to Mayer, could make me feel sick regardless of what the food was actually doing to me.
Mayer puts his patients with digestive issues on a classic elimination diet: He tells them to keep a food diary, and write down if a symptom is noticeable enough to disrupt them from their day. If they want to, they can try eliminating it for a week. If that makes them feel better, they can choose to stay away, or just eat it in low amounts. This may not sound too different from what Pinnertest and Everlywell suggest, but Mayer says being in control makes all the difference.
“It has the benefit that it empowers the patient,” he says. “It’s the patient who makes the determination, it’s not some lab telling them what they can’t eat. And most of them will end up with a relatively small list. Often it’s only one item.”
If I take a step back, I can see how weird it is that food intolerance tests are "trendy." What's cool about a medical test?
Lisa Hayim is a clinically trained registered dietician who got her master's degree from Columbia University in nutrition, exercise, and physiology. She also happens to have a foothold in the Instagram “wellness” world, with more than 50,000 followers on her account, @thewellnecessities. (She’s never posted about a food intolerance test.) Hayim says that many of us can be unconsciously seeking out reasons to not eat certain foods, because of an unhealthy mental relationship with food. If a new client comes to see Hayim after having taken one of these tests, “we sort of have to take a big step backwards.” She says she’ll take it into consideration, but like Mayer and Hamilton, would rather rely on a more general elimination diet, if she thinks it's needed.
She tells me that even if the results of at-home food intolerance tests were one day valid, people would still be left with the aftermath: “What do I do next?” she says. “And that is the problem. That’s what can cause this form of disordered eating. Not necessarily related to weight gain, but a disordered relationship to being hyper-healthy.”
Hayim says she sees this a lot and in response, she co-founded a course called Quiet The Noise, hosted with Dr. Naomi Arbit, that brings people together to talk about food fears, intuitive and mindful eating, and food freedom. A lot of people, especially those immersed in the wellness world, can be stuck in similar mindsets that food intolerance tests create: That foods are either “good” or “bad.”
Hayim says that an understated risk of these tests is that it can affect your nutritional health as well. “You basically end up sticking to the foods that are so safe but aren’t necessarily bringing in all the important nutrients and vitamins into your body," she says.
If I ended up quitting all the foods that Everlywell told me to, that’s exactly what I’d do. Instead of eating curiously and with pleasure, or trying foods of all types, I’d be bogged down by rules and end up settling for what I knew (or thought I knew) was safe.
Hayim doesn’t think that bloggers or influencers need to necessarily stop sharing their experiences with these tests or diets, but they do need to be more transparent about where they’re coming from. “They’re allowed to share their story and their experience and I think that’s really insightful,” she says. “What worked for somebody might work for another person. But it also might not. So I really appreciate disclosures. Many of these tests have not been formally validated and just because they are testing your blood, which seems so cellular and fact-based, doesn't mean that they are the end-all.”
I'm a little more cynical; I have yet to see an Instagram account say: I took this test and decided not to eliminate these foods. Nor have I seen one that questioned the science behind IgG prediction of food intolerance. And that’s probably because influencers are being paid to promote these products.
Instagram aside, if you’ve found yourself unwittingly placing foods in the “bad” category, for whatever reason, Hayim has some tips for bringing them back into your life. “Give yourself an opportunity to do what you think is so bad,” she says. “That’s really important. I even do that for myself. There are foods that used to be on my 'bad' list and I will eat one or two of them at dinner. I might say to myself, 'Lisa, let’s see how mentally strong you are. Let’s see if you can tackle this food.' And I’ll have one or two and that’s the end of it."
Remember: this doesn’t apply for true food allergies, or foods that through a proper elimination diet you’ve decided don’t sit right with you. But if you’re like me, and you’ve eliminated a whole bunch of foods for no valid medical reason, it’s good to challenge ourselves and bring them back, without fear. Hayim suggests starting slow, and if you’re feeling nervous, to try a food again at home, by yourself; not out at a crowded restaurant with your in-laws.
Armed with her advice, I’m going to try again. I am proud that I when I got my Everlywell results I felt I had the power to ignore them; I even ate a handful of walnuts as I was reading it. Maybe combining three of my banned foods into one super-triggering oatmeal breakfast wasn’t the best way to start, but I think there’s a spoonful of almond butter straight from the jar in my very near future.