Supplement companies claim that prebiotics (which are one thing) and probiotics (another thing!) can strengthen immunity, aid weight loss, and even extend life. But is any of that true?
Here’s what you should know:
What are prebiotics?
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.
What are probiotics?
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.
When to take prebiotics:
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.
When to take probiotics:
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.
What to look for on the label:
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.
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.
The bottom line: If you’re a healthy man without GI concerns, you should put your money toward fiber-rich whole foods rather than supplements. Head to the doctor, though, if you suspect a food allergy or an inflammatory-bowel condition isbehind your stomach woes. It’s best to let them decide on the pre- or probiotic you should take.