Are Gut Boosters BS?

Supplement companies claim that prebiotics (which are one thing) and probiotics (another thing!) can strengthen immunity, aid weight loss, and even extend life. MELISSA MATTHEWS fact-checks all that.


They’re soluble fibers, so they attract water during digestion. They also contain oligosaccharides, sugars eaten by gut bacteria, says Bethany Doerfler, R.D., a clinical research dietitian at Northwestern University.

After your gut bacteria feast upon these oligosaccharides, they release short-chain fatty acids, which may relieve discomfort in people who have inflammatory-bowel disorders or conditions like IBS.

WHY TAKE THEM If you’re not hitting the recommended 38 grams of fiber daily, you’re at risk of constipation (at best) and heart disease (at worst).

Prebiotic supplements help with fiber intake, but Doerfler says she likes to see the $30 to $40 per month that people might spend on a dietary supplement go toward buying healthy foods that are rich in prebiotics. IF YOU BUY THEM Go with a mix of soluble fiber, such as psyllium, and an oligosaccharide that has at least five grams of fiber per serving, says Doerfler.

(The label may list chicory root, artichoke hearts, inulin, or oligosaccharides—same difference.) Ignore claims about a company’s “signature” blend. It’s just marketing.


They’re microorganisms found in fermented foods like yogurt and kimchi, says Jack Gilbert, Ph.D., a researcher at the University of California, San Diego.

Companies claim their probiotic supplements can improve your immunity or help you lose weight. The jury is still out on those benefits, but science does show that probiotics can relieve symptoms of Crohn’s disease, inflammatory-bowel disease, and food allergies, says Gilbert.

WHY TAKE THEM You suffer from chronic constipation, diarrhea, or other gastrointestinal distress— and your physician recommends taking something, says David Poppers, M.D., Ph.D., a gastroenterologist at NYU Langone.

Everyone else can save their money because there’s no evidence that probiotic supplements offer any benefit to already healthy people, says Gilbert. IF YOU BUY THEM Your doctor will recommend a probiotic shown to help with your specific complaints, says Dr. Poppers. For example, one bacteria, Lactobacillus Rhamnosus GG, is better for those with diarrhea, compared with other strains, Gilbert says.

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