By Stephanie Stahl

PHILADELPHIA (CBS) — Millions of people take a supplement of probiotics, but a new study says labels on many probiotics do not give consumers the information they need to make an informed purchase. Probiotics are live micro-organisms that are good and healthy bacteria, and are found in things like yogurt.

Probiotic supplements are taken to improve digestive health and the immune system. But scientists say labeling on them can be lacking.

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Katie Linden is a holistic health coach and a busy mom. She strongly believes in the benefits of probiotics.

“It helps with my digestion, so less bloating, ease of digestion, ease of elimination, helps my skin,” Linden said.

But she says choosing a probiotic is not easy.

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“That’s a bit challenging when you look at the grocery stores and the health food stores. But you really want to research the company,” Linden said.

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New research examined the labels of 93 different types of probiotics commonly found in drug stores. The study revealed only 33% of the probiotic labels could be linked to health benefits supported by clinical evidence and many lacked basic information consumers need to make an educated choice.

“Often, they wouldn’t list a dose, they wouldn’t list a strain. This is not illegal, but it’s just not helpful for people to know if there’s evidence or not,” Dr. Dan Merenstein, with Georgetown University Medical Center, said.

Researchers say the best way to know you’re getting the kind of probiotic you want is to look for a label that lists the family, species and strain of the live bacteria. A high number of strains is not necessarily a good thing.

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“Let’s say I have 10 different strains, but every one of them is a super low dose, it’s probably not going to do anything, probably not even going to survive to get through the stomach,” Merenstein said.

Researchers say there’s a growing number of studies that show the benefits of probiotics. That’s why Linden vows to keep doing the research for herself and her clients.

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Probiotics are sold as dietary supplements, which do not require FDA approval.

Stephanie Stahl