The Truth About Probiotics

 Photograph by Shana Novak

Probiotics seem to be everywhere. These microorganisms, which multiply in the gut and balance out bad bacteria, are now added to cold-brew coffee, kale chips, nut butters, frozen burritos, and even bottled water. Sales of probiotic supplements, meanwhile, hit $1.7 billion last year and are projected to reach $2.3 billion by 2018. Not so shocking, given that food and drug companies now push probiotics as a way to fend off everything from eczema to depression and migraines.

Popping a pill or devouring a bean burrito to safeguard health is alluring. But there's a problem: "The strength of evidence is not sufficient for healthy individuals, without any medical problems or digestive issues, to be investing in daily probiotics," says Dr. K.T. Park, a gastroenterologist at Stanford University School of Medicine.

One reason is that most supplements provide a single strain of bacteria — but your gut is home to hundreds. Finding the right strain of probiotic supplement to help boost your unique microbiome is a crapshoot at best, says Dr. Tod Cooperman, president of ConsumerLab, an independent supplement-testing company.

If you do take an uncoated capsule, there's a good chance your stomach acid will kill many of the bacteria strains before they can work. "Unless it's encapsulated and designed for delayed release, the average probiotic won't survive long in your body," says Jeremy Burton, deputy director of the Canadian Centre for Human Microbiome and Probiotics. One study found that just 10 to 25 percent of uncoated strains survive once swallowed.

Another issue: To aid the gut, microorganisms must be alive when consumed — but many of those inside a supplement, food, or drink are often DOA. In fact, ConsumerLab reports that roughly half of the organisms initially put into a product are dead by the time they hit store shelves.

As for the ever-growing number of probiotic-infused chocolate bars, ice creams, crackers, and frozen foods, no research has proved that they have probiotic benefits, and experts say most are merely gimmicks to lure the health-obsessed. "If a food is inherently unhealthy, sprinkling a little good bacteria on it won't make it any better for you," says Park.

That's not to say the microorganisms themselves are problematic. Science shows that naturally occurring probiotics are beneficial for your microbiome. But they should be consumed in whole foods — yogurts, sauerkraut, kimchi — that are loaded with billions of colony-forming units (CFUs) of friendly bacteria, along with fiber that feeds the microorganisms in your gut. Cooperman says you want at least a billion CFUs to get a positive effect. While a serving of kimchi may provide several billion CFUs from a variety of bacteria strains, many supplements and fortified foods barely reach a half billion of one strain — if they're even alive when you consume them.

Park's advice is simple: "Instead of expensive supplements, spend that money on a plant-based diet that includes fermented foods. That will give your gut bacteria enough fiber to create a healthy biome."

How to Get the Most from Probiotics

Three rules to ensure you're loading up on the best good bacteria.

Watch for sugar.

Yogurts and drinks like kombucha are rich in naturally occurring probiotics, but many brands are sweetened with 20-plus grams of sugar. This can negate the gut benefits. Skip any product for which a sweetener is one of the first ingredients listed on the label.

Be smart about supplements.

If you buy them, look for shelf-stable capsules with at least a billion CFUs per dose. Because bacteria can die during shipping, you want a brand that lists its CFU number with a "best by" date, not "present at time of manufacture."

Eat fermented foods frequently.

Occasionally topping a ball-game bratwurst with kraut doesn't do much for your microbiome. To get the benefits of fermented foods, you must eat them often. Work yogurt, tempeh, and pickled produce into your daily diet.