Private food tests promise to reveal your food sensitivities. But is it just a pseudoscience?

The tests claim to be able to identify food sensitivities associated with headaches, lethargy, brain fog, depression and an huge array of other symptoms

Sharon Kirkey, National Post 7 minute read December 17, 2019

Dr. David Stukus recently used a trendy at-home food sensitivity test, complete with alcohol swabs, gauze, lancets and a biohazard bag.

He cleaned his ring finger with the alcohol prep pad, pressed a lancet against the “puncture site” until it clicked, squeezed his finger to get a good drop of blood to form and then dabbed it on the blot card.

Seven days after mailing off his dried blood sample, the results came back suggesting Stukus was sensitive to sesame, sunflower, black walnuts, cashews, watermelon, yogurt, carrots, cottage cheese, asparagus, tarragon, safflower, tomatoes, brewer’s yeast, broccoli, chicken, barley, soy beans, baker’s yeast, white potatoes, cow’s milk, cheddar and mozzarella cheese. Twenty-two foods.

“It even broke down mozzarella versus cheddar cheese, which is just ridiculous,” said Stukus, a pediatric allergist at Nationwide Children’s Hospital in Columbus, Ohio.

In a live Twitter video, Stukus shared his experience with the IgG test, which identifies immunoglobulin G, the most common antibody found in blood and other bodily fluids. It plays an important role in the body’s immune system, but IgG tests claim to be able to identify food sensitivities associated with headaches, lethargy, brain fog, memory problems, depression, insomnia, ADHD, bloating, puffiness and an astonishing array of other symptoms. Once the “reactive” food is eliminated from someone’s diet, unpleasant symptoms are supposed to disappear.

Except, according to allergy and immunology groups the world over, the test is a marketing gimmick wrapped in pseudoscience and has never been scientifically proven to be able to accomplish what it claims to do.

Allergists in Canada say they are seeing a growing number of people being referred to their offices brandishing the results of IgG food tests — a trend that’s being helped along by online marketing, endorsements from self-help celebrity gurus (no dairy, grains, gluten, meat or shellfish for Gwyneth Paltrow) and a tendency to self-diagnose in today’s risk-obsessed society.

It’s also a product of some serious confusion around food reactions.

A true food allergy causes an immune response and the production of another antibody, immunoglobulin E. It usually happens within minutes, and it happens every time the person eats the food. But food sensitivity is a vague, nebulous term often used by naturopaths and other alternative medicine practitioners that has no clear definition.

“It’s just kind of thrown around loosely, it’s not a specific medical diagnosis,” said Dr. Harold Kim, president of the Canadian Society of Allergy and Clinical Immunology.

People can also have a food intolerance, if they lack the ability to digest certain foods. One of the most common is lactose intolerance, a deficiency in lactase, the enzyme needed to break down milk sugars. The lactose molecules travel through the gut undigested, drawing water into the intestines and causing cramping, diarrhea and bloating. Celiac disease is different. It’s an autoimmune disorder that causes damage to the small intestines. People can’t tolerate even small amounts of gluten, the gluey protein found in wheat, barley and rye. Only one per cent of Canadians have celiac disease, but more than 20 per cent have eliminated or reduced gluten in their diet.

With a food intolerance, the symptoms are primarily limited to the gut. But proponents of IgG tests blame food sensitivities for everything from poor sleep and brain fog to autism.

Labs that market IgG tests claim that food sensitivities are delayed reactions to certain foods that are triggered by the IgG antibody. Reactions, they say, can take hours or even days to develop, which makes it that much harder to determine exactly which food is responsible without testing.

Critics say the costly tests not only lack biological plausibility, they risk increasing warped and disordered ideas around eating and “nutrichondria”— a hyper preoccupation with food.

“Many patients suffer from physical, psychological, and psychosomatic conditions for which conventional medicine cannot provide diagnosis or treatment,” Dr. John Kelso writes in the Journal of Allergy and Clinical Immunology: In Practice.

“Such patients understandably turn to practitioners who tell them that these ailments are the result of ingestion of certain foods” and that eliminating them based on sensitivity testing will ease their symptoms. Many people feel better “because they feel like they have an explanation for their illness,” he said.

The concern is that, in addition to the cost, IgG testing can increase anxiety and lead to useless food avoidance diets, and possible nutritional deficiencies.

People could become obsessed, “reading labels and taking extra precautions to make sure they don’t have an accidental bite of a food they’re not even sensitive to in the first place,” Stukus said.

Stukus describes IgG as a “memory” antibody that forms after exposure to vaccines, infections and most any other environmental exposure, including food.

“It’s a normal physiological response to the food we eat,” Stukus told the Post. “Even if it is elevated — and we don’t even know what a ‘normal’ level is — it doesn’t indicate anything bad. If you eat a food you will produce IgG.”

If anything, the antibody indicates tolerance, not intolerance, he said. Studies have shown that, as allergies wane, IgE goes down and IgG goes up.

Sometimes reactions appear for foods rarely eaten. Stukus tested sensitive for cottage cheese, something “I’ve never eaten in my life.” (The companies claim the reaction may be the result of “cross-sensitivity” with a related food.)

There is also the risk that a true, bonafide food allergy will be missed, because it tests for the wrong antibody.

Dr. Harold Kim recently saw a man whose IgG test came back negative for shrimp. Kim conducted a skin test, which measures IgE antibodies — the antibodies involved in allergic reactions. “The skin testing was strongly positive” for shrimp, Kim said.

In severe cases, shellfish allergies can lead to life-threatening anaphylaxis, when lips, tongues and airways swell.

In 2012, Kim’s group — the Canadian Society of Allergy and Clinical Immunology — warned that no body of research exists to support the use of IgG testing to diagnose adverse reactions to any food. The statement holds true today, Kim said.

“The labs are charging hundreds of dollars for these tests. I heard from one patient recently who paid $900 for this test by her naturopath. She was referred to us to rule out allergies to the 40 or 50 different foods that were picked up,” he said.

“I think it should be the responsibility of the regulators, the government, the laboratories, and the medical people at the laboratories to say, ‘You know what? I don’t think we should be doing this because it’s not scientifically validated and it doesn’t seem like the right thing to do.’”

While Americans can order at-home IgG tests online, Canadians require a requisition signed by a doctor, naturopath or nurse practitioner. In Ontario, Dynacare charges $325 for an IgG blood test that tests for 200-plus foods.

“Dynacare relies on the professional expertise of the ordering professional to determine the appropriateness of ordering a particular test,” the company said. “While debate exists, there are peer-reviewed articles suggesting there is use for the food IgG test.”

For example, one 2004 study involving 150 people with irritable bowel syndrome found those who excluded foods to which they had raised IgG antibodies showed an improvement in symptoms after 12 weeks. Other studies have suggested IgG-based “elimination diets” can help with migraines and  symptoms of Crohn’s disease.

Kelso, writing earlier this year, said a placebo effect might be at work for some. “Although it is important to be sympathetic with these patients, as scientists, it is also important for us to gently explain that these tests have not been validated by science.”

Stukus suggests that, if someone suspects a food is causing a particular problem, they should eliminate it and then reintroduce it to see if the symptoms return.

“But there is zero indication to ever just do a bunch of tests for random foods and see what you get,” he said.

National Post

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