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• Posted February 19, 2025

Blood Test Could Guide Better Diet For Irritable Bowel Syndrome

A blood test can help people with irritable bowel syndrome cut out specific trigger foods most likely to worsen their condition, a new study suggests.

About 60% of IBS patients who followed a diet guided by the results of the blood test wound up suffering less stomach pain, researchers reported recently in the journal Gastroenterology.

By comparison, 42% of IBS patients who didn’t get the blood test experienced a reduction in stomach pain, results show.

The test “requires additional validation but could move us one step closer to a ‘precision nutrition’ approach, in which providers can offer personalized dietary recommendations to each patient with IBS,” researcher Dr. William Chey, chief of gastroenterology and hepatology at the University of Michigan, said in a news release.

The blood test, called inFoods IBS, tests for the potential of 18 foods to worsen IBS symptoms in specific patients. These include wheat, oat, rye, whole egg, yeast, cow’s milk, black tea, cabbage, corn, grapefruit, honey, lemon and pineapple.

The test looks for blood levels of an antibody called immunoglobulin G (IgG) that’s produced when the gut has an allergic reaction to a type of food. Higher levels of this antibody mean a person likely would benefit from cutting this food from their diet.

About 10% to 15% of Americans have IBS, and it’s well-known that certain foods can worsen symptoms and cause flare-ups, researchers said in background notes.

“We have patients all the time who say, ‘I know food is a problem for me. Is there any way to figure out which foods I'm sensitive to?’ ” lead researcher Dr. Prashant Singh, a University of Michigan gastroenterologist, said in a news release.

For the study, researchers recruited nearly 240 IBS patients. All provided a blood sample that was used to detect which foods were most likely to worsen their IBS.

They then were randomly assigned to either follow a diet that eliminated foods based on the blood test results, or to follow a “sham” elimination diet.

In the sham diet, people were asked to cut out foods that were similar to those for which they tested positive for allergic reaction. For example, a person who tested positive for walnuts would be asked to eliminate almonds from their diet.

Results showed that more people had less stomach pain in the group that ate based on the blood test.

The benefits were most pronounced in people who had IBS with constipation (67% versus 36%) or a mixture of constipation and diarrhea (66% versus 30%).

Elimination diets can help people treat their IBS without resorting to anti-inflammatory drugs, but these diets are often tough to follow because they restrict a wide range of foods, researchers noted.

This test can help patients by targeting only a few specific trigger foods, based on their own individual test results.

“Our diets are complex and identifying dietary triggers can be difficult,” senior researcher Dr. Anthony Lembo, vice chair of research at the Cleveland Clinic’s Digestive Disease Institute, said in a news release. “This IBS-specific IgG test can help patients who suffer from IBS identify specific dietary triggers."

The clinical trial was funded by Biomerica, developer of the inFoods IBS blood test.

The blood test has not yet been cleared or approved by the U.S. Food and Drug Administration, according to the company.

More information

The Cleveland Clinic has more on irritable bowel syndrome.

SOURCE: University of Michigan, news release, Feb. 13, 2025