Scientists use the term “probiotics” to describe live microbes that have been tested in human studies and found to provide a health benefit. But the Food and Drug Administration doesn’t regulate the use of the term, and marketers use it liberally, sometimes to describe products that haven’t been thoroughly researched.
To tell if a product is truly a probiotic, you might need to check product websites to see if the claims are backed up by results from actual studies. Here are some other things to look for on the product label.
• Strain. A probiotic is defined by its genus (e.g. Lactobacillus), species (e.g. rhamnosus), and strain designation (often a combination of letters or numbers, such as “GG”). In studies of antibiotic-associated diarrhea, researchers used a variety of Lactobacillus species and strains, and the yeast Saccharomyces boulardii. These organisms can be found in many probiotic foods and supplements, including DanActive dairy drink, and pills and packets of powder with the brand names BioK Plus, Culturelle, Florastor, and VSL#3.
• Dose. Probiotics are measured in colony forming units, or CFUs. Different probiotics have been found to be effective at different levels, and it’s not possible to provide a one-size-fits-all recommendation. To prevent antibiotic-associated diarrhea, taking 10 billion CFUs per day might be more effective than taking a lower dose. In most probiotic studies, patients started taking one at the same time as an antibiotic and continued with the treatment for up to two weeks after the antibiotic was stopped. Probiotic yogurt, powders, and pills should work equally well if they contain an effective dose of the right strains.
• Manufacturer. Probiotics are regulated as foods or dietary supplements in the U.S., which means they aren’t scrutinized as closely as prescription and over-the-counter drugs and don’t have to meet the same standards for effectiveness. Studies have shown that some probiotic products might not contain the dose of the organisms listed on the label, or that they might contain bacteria that aren’t listed. A reputable company should include an expiration date for the dosage of live bacteria on the label. It should also provide storage instructions, including refrigeration.