It's a daunting aisle in the supermarket, filled with tubs of yogurt. Before you grab one, keep in mind that not all probiotic products are equal, according to a new study.
Mary Scourboutakos, a postdoctoral researcher, was inspired to study probiotic yogurt when she was trying to figure out what to eat. Her study, published Wednesday in the journal Nutrient, starts to provide some clues.
"What we wanted to do with this study is cut through the hype," Scourboutakos said.
What are probiotics?
Probiotics are beneficial bacteria added to food products. They were originally studied to restore the balance of gut microbes after taking antibiotics. Now probiotic yogurts are promoted to help digestion and even improve specific conditions.
To find out what probiotics are in which product, and how much there actually is, Scourboutakos and her co-authors searched a national database of product labels that covers three-quarters of the grocery market share in Canada.
To make the basic claim "promotes a healthy gut flora" in Canada, a yogurt needs to contain one billion units of probiotics. The study's authors say that minimum standard was met.
To look for potential additional benefits beyond gut health, the researchers looked through 29 randomized clinical trials on various health effects, ranging from preventing the common cold, to reducing cavity-causing bacteria among healthy populations.
Most studies funded by probiotic makers
Most of the studies were funded by probiotic makers. Some results also need to be interpreted with caution, said study co-author Elena Comelli, an assistant professor of nutritional sciences at the University of Toronto.
Comelli pointed to four additional potential benefits:
- Improving intestinal health.
- Crowding out harmful bacteria.
- Preventing the common cold.
- Helping with irritable bowel syndrome symptoms.
"For these additional benefits, some of them, they are proven. There is research to back these up. But in order to get them by consuming these yogurts, we would have to consume more than the actual serving, up to 25 more [servings]."
The World Health Organization recommends that suggested serving sizes on the product label deliver the effective dose related to a health claim.
No agreement on which is best
For the additional health benefits related to cold and flu or diarrhea, the researchers say one to three servings of a yogurt drink are needed.
Kefir products had more helpful bacterial strains and often at the highest doses, but the strain mixes haven't been studied yet.
The researchers summarized the potential health benefits in this chart.
The study's authors noted there is no consensus on what strain, minimum dose or product is best. More research is needed.
What's more, the benefits could vary depending on an individual's lifestyle or normal levels and types of gut microbes.
Dietitians also advise people to check the sugar, artificial sweetener, fat and calorie content when choosing yogurt.
About four ingredients are all you need, said Christy Brissette, a registered dietitian in Toronto.
"Some yogurts can be the equivalent of having a cup of soda, so you definitely want to make sure that you're looking at that ingredients list," Brissette said.
Fermented foods, such as sauerkraut and kimchi, are also sources of probiotics.