Food is one of life’s pleasures, but it can also be a source of pain — especially if you’re among the tens of millions who regularly experience digestive issues such as heartburn, abdominal pain, bloating or diarrhoea. When those symptoms strike, you may wonder: are certain foods to blame?

Food-sensitivity tests promise to supply answers. For decades, these tests were offered mainly in providers’ offices in alternative-medicine settings. Now, they are increasingly available as at-home tests you can purchase online or in drugstores. Manufacturers claim that with several drops of blood or a few plucked hairs, they can identify the foods that are causing your discomfort. Once eliminated from your diet, you’ll be on the road to relief.

That a simple test could guide dietary changes and improve common, disruptive symptoms is certainly appealing. But do these tests work? We asked some experts and looked into the research to find out.

What is a food sensitivity, anyway?

According to Dr David Stukus, director of the Food Allergy Treatment Center at Nationwide Children’s Hospital in Columbus in Ohio in the United States, the term food sensitivity is used more in marketing than in medicine. “There really is no consensus definition of what a food sensitivity is,” he said.

The companies selling these tests typically describe food sensitivity as what happens when a specific food triggers digestive issues or gut inflammation, causing symptoms such as abdominal pain, bloating or headaches. Symptoms may appear hours or even days after eating, and often resolve when the offending food is avoided.

When physicians or dietitians refer to such issues, they’re more likely to use the term food intolerance, Stukus said (although some may use food sensitivity, too), such as with lactose intolerance, which can cause constipation, diarrhoea and bloating as a result of the difficulty in digesting the sugar found in milk. Similarly, people with irritable bowel syndrome, or IBS, may be sensitive to certain kinds of carbohydrates called Fodmaps, and altering their diet may relieve their symptoms.

A food intolerance or sensitivity is different from a food allergy, which is an immune reaction to certain foods that can cause more severe symptoms such as vomiting, hives, shortness of breath or even life-threatening anaphylaxis, usually within minutes of eating even a small amount. There are also more chronic immune reactions to foods, such as those from celiac disease, a serious autoimmune condition triggered by gluten.

At-home food-sensitivity test kits can be ordered online or purchased over-the-counter at drugstores. Depending on the test type, you pluck several hairs or prick your finger to drop blood onto a paper card, and then mail in your sample. Within weeks, you’ll receive digital results, including a list of foods causing problems.

Some tests claim to determine your sensitivity to hundreds of foods and ingredients by measuring the “bioresonance” of your hair, an unproven technique used in holistic or complementary medicine that involves measuring the energy wavelengths coming from your body. Others measure the levels of certain antibodies, called IgG antibodies, in your blood to come up with results.

Still other tests, called Alcat and MRT tests, require a blood draw from a lab and measure how the size of your blood cells change after exposure to food extracts in a test tube, said Dr John Kelso, an allergist at Scripps Clinic Carmel Valley in San Diego, US.

Aside from the breath tests that gastroenterologists sometimes use to diagnose certain intolerances, such as those to lactose or fructose, there aren’t validated tests for food intolerances or sensitivities, said Tamara Duker Freuman, a registered dietitian at New York Gastroenterology Associates in New York City, US. The only way to figure out if you are sensitive to certain foods or ingredients is to see how your symptoms change after eliminating them from your diet, ideally with the help of a registered dietitian or physician, she said.

This can be a slow process involving trial and error, and the companies selling food-sensitivity tests market them as a shortcut. But medical organisations, including those in the United States, Europe and Canada, have recommended against using food sensitivity or intolerance tests because there is no good evidence that they actually work.

“There isn’t anything in your hair that would tell you anything about your sensitivity to food,” Kelso said. And the antibodies measured in the IgG tests are produced as part of the immune system’s normal response to foods; they haven’t been shown to correlate with symptoms or intolerances, Stukus said. “It’s really just a reflection of what you’ve eaten.”

There can be downsides to trying these tests.

Food sensitivity testing can cause people to unnecessarily avoid a long list of foods, missing out on those they enjoy and potentially becoming susceptible to nutrient deficiencies, said Dr Frances Onyimba, a gastroenterologist and assistant professor of medicine at the University of Maryland School of Medicine, US.

The tests can also leave people anxious about eating, which can sometimes develop into eating disorders, Stukus said.

NYTNS