Little Evidence Popular Food Intolerance Tests Work

Patient pricks her finger for an at-home test to collect blood.  (Lauren Hanussak/KQED)

Numerous online companies are trying to drive a revolution in lab testing by making it possible for you to skip the doctor and test for fertility, sleep hormones and even vitamin deficiencies -- all from the privacy of your bathroom -- no lab visit required.

Do-it-yourself testing kits cost anywhere from about $35 for an individual test to $450 for a battery of tests.

Last November on "Shark Tank," the reality show featuring budding entrepreneurs who think they have a hot idea, contestant Julia Cheek hawked her company's home-testing kits to the program's panel of investors.

"EverlyWell is transforming lab testing — a $25 billion market — to be simple, convenient and useful for you," Cheek pitched.

"I think the product is brilliantly crafted," said Lori Greiner, who is also known as "The Queen of QVC."

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"I think this gives people an empowered way to check on some things."

Cheek walked away from the show with a million-dollar commitment for her Austin-based company.

But that was TV, of course. Some doctors worry EveryWell is promising more than it can deliver.

One Woman's Success Story

The company's food-sensitivity test is its best seller, and the kit is especially hot in the Bay Area. San Francisco resident Regina Du says the test has changed her life. For years Du missed work due to stomachaches, headaches and inflamed welts.

“I just felt crummy," said Du. "I would just like uncontrollably scratch myself because I was so itchy."

Doctors couldn’t figure out what was wrong. Eventually Du landed under the care of an allergist, who ordered a test. But Du balked when she learned her insurance wouldn’t cover the $700 cost.

“I just had total sticker shock," Du said.

So, she poked around online and found EverlyWell's food sensitivity kit for a couple hundred bucks.

Instructions inside the neatly packed kit explain how to prick your finger and dribble drops of blood onto a white collection card. Du completed the test in less than 20 minutes during her lunch break. A few days later she got an email suggesting she avoid gluten, dairy and green beans.

Almost immediately: Du started feeling better. Within a few weeks she felt normal for the first time in eight years.

Does it Work?

The test is supposed to measure whether a person’s immune system reacts to certain foods by making an antibody called Immunoglobulin G (IgG), which EverlyWell describes on its website as the potential cause of  symptoms like migraines or irritable bowel syndrome according to some small studies.

Julia Cheek, CEO of EverlyWell, on a November 2017 episode of 'Shark Tank.' (Courtesy ABC/Sony Pictures Television)

The American Academy of Allergy, Asthma & Immunology does not recognize the validity of IgG tests in diagnosing food sensitivity, also called food intolerance.

"It is important to understand that this test has never been scientifically proven to be able to accomplish what it reports to do," the AAAAI writes on its website. "The scientific studies that are provided to support the use of this test are often out of date, in non-reputable journals and many have not even used the IgG test in question. The presence of IgG is likely a normal response of the immune system to exposure to food."

Dr. Neha Shah, a rheumatologist and immunologist at Stanford University, is one doctor who is skeptical.

“What we don’t have is proof that having a high IgG level against a particular food item means that that food is causing your symptoms," said Shah.

Shah shares the story of her sister, who bought a test and then was told to avoid swordfish.

“We’ve been vegetarians all our whole lives," said Shah. "And there was really no reason why she had a high sensitivity, a high IgG level against swordfish.”

Shah also says IgG levels can elevate simply because you eat a specific food, so it doesn't necessarily mean that your body is reacting negatively. For all these reasons, Shah does not administer food sensitivity tests in her practice. She suggests patients save the money and go straight to an elimination dietwhere you remove commonly reactive foods like gluten or dairy and see if you feel better.

Test for Heavy Metals, Stress or Metabolism

Dr. Marra Francis, EverlyWell's executive medical director, stands by its products as a valuable first step for patients to take their health into their own hands.

"A lot of times this testing can be a bridge between vague symptoms and an actual plan that you create with your provider," she said. EverlyWell does recommend patients double-check test results with an elimination diet.

Tina Heilman, a spokesperson for EverlyWell, wrote in an email:

"EverlyWell recognizes 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. IgG tests are currently ordered by thousands of medical providers in the U.S."

No Oversight

Besides its IgG test, the company markets 22 other home wellness tests, everything from cholesterol to testosterone. Internet ventures like LetsGetChecked, Thorne and Health Test Express offer a similar array.

But some doctors worry about a booming market that's not regulated by the Food and Drug Administration.

“A lot of this kind of huxterist testing is keying off of the placebo effect," said Dr. Norman Paradis, a clinical lab expert who teaches at the Geisel School of Medicine at Dartmouth College, referring to the industry in general and not to a particular product.

In other words, just believing a test is valid and taking action on it may make you feel better. Paradis is also worried that home tests could inspire patients to overreact to results. Hypothetically, a patient may discover she's deficient in vitamin d and compensate by taking toxic doses, he said. Or a test result may inspire a patient to seek medical care they don’t need.

“For instance, let’s say a test inaccurately said you may have colon cancer," said Paradis. "And then you went and got a colonoscopy and were injured during the colonoscopy. Well the test actually created that harm.”

Dr. Gilbert Welch, the author of "Overdiagnosed: Making People Sick in Pursuit of Health," said, "You can't test your way to health."

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For unexplained symptoms he suggested starting with the long-ignored advice from your grandmother: Eat real food, set a regular sleep schedule, and get some exercise.

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