Should You Take a Probiotic Every Day?

What if you don't have a GI tract problem?


“One of the biggest misconceptions about probiotics is that you should be taking them daily like multivitamins,” says researcher Lynne McFarland, an associate professor at the University of Washington Medical Center. “If you don’t have any reason to think there’s something wrong with your digestive system, a probiotic probably isn’t going to do much for you.”

But if someone is struggling with GI problems, adds Mary Ellen Sanders, “I tell them to try the strain-specific probiotic products that have been tested and shown to have an impact on the symptom they’re trying to deal with.”  Sanders is Executive Science Officer of the International Scientific Association for Probiotics and Prebiotics, a group of academic and industry researchers funded by probiotics manufacturers and food companies.

Do probiotics contain what they claim?

Major brands, at least, seem to have what’s supposed to be in them and at levels high enough to be useful. When Consumerlab.com recently tested  19 popular brands of probiotic supplements, it found that all contained the organisms that were listed on the labels. And  18 of the  19 provided at least  1 billion live organisms. If a probiotic works, that’s the minimum dose needed, most researchers agree.

A new universe within and on us.

About 30 years ago, the GI tract, with its microflora of bacteria, was like a black box,” McFarland explains. “We weren’t even aware of most of the microbes in there because they don’t grow in a petri dish, which was the only way available then to identify them.”

Today, scientists can easily identify bacteria from fragments of their DNA.

And what they’re uncovering is a vast, largely unexplored world that may play a critical role in the body. Among other things, our gut bacteria help digest fiber and synthesize vitamin K. Some even secrete antibacterial compounds that can attack nasty bugs.

And there are hints—though so far little solid evidence—that our intestinal microflora may influence whether we become overweight or are susceptible to diabetes.

It’s enormous.  The collection of microorganisms in the gut—our microbiome—seems unimaginably large. By some estimates, as many as 500 to  1,000 species of bacteria inhabit our intestines, and the roughly  100 trillion microorganisms in those species are around  10 times greater than the number of cells in our body.

We don’t start out that way. When we’re born, our GI tract is sterile. But it immediately begins to be colonized by bacteria from the environment.

“This process doesn’t stabilize until we’re about three years of age and start to eat an adult diet,” notes Tiffany Weir, an assistant professor of food science and human nutrition at Colorado State University. From childhood on, your microbiome remains fairly stable.

What does a healthy microbiome look like? “It’s really difficult to define,” says Weir. “But one of the things we look for is diversity, because that tends to fill all of the ecological niches in the gut, which prevents pathogens from being able to come in and take hold.”

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