If you swear by probiotic foods and drinks, you may be wasting your money.
A Danish team of researchers reviewed current research on the supplements, and their findings suggest they may have zero impact on healthy adults.
Examining the results over the course of seven trials of the products, they found no evidence of changing compositions of fecal bacteria.
The hype for lacto-fermentation of foodstuffs – typically milk-based drinks, biscuits, sachets, or capsules – has been egged on by online writers and magazines. They’ve been touting the range of health benefits, including better digestion and a higher resistance to infections.
“While there is some evidence from previous reviews that probiotic interventions may benefit those with disease-associated imbalances of the gut microbiota, there is little evidence of an effect in healthy individuals,” said Oluf Pedersen, who led the research at the University of Copenhagen.
If you aren’t familiar with probiotics, they’ve been coined ‘friendly bacteria’. Probiotic foods contain live microbial food ingredients, which are said to provide health benefits through improving intestinal microbial balance. There are branded products that are specifically marketed as probiotic supplements, other natural probiotics include plain yoghurt, sauerkraut, miso and kefir.
Supporters of probiotics say they help with digestive health, allergies, immune response and obesity.
But after Pedersen & Co. reviewed the seven randomized studies to see if daily probiotic supplements had any effect on microbial composition of healthy adults’ feces, only one showed change.
“According to our systematic review, no convincing evidence exists for consistent effects of examined probiotics on fecal microbiota composition in healthy adults, despite probiotic products being consumed to a large extent by the general population,” said Nadja Buus Kristensen, a PhD student and junior author of the study.
Each of the seven studies had a wide variety of participants, varying in age and the amount of people. Amounts ranged from 21 to 81 participants, and subjects aged 19 to 88.
The researchers did note that they’ll need to increase the sample sizes, as well as accounting for the participant’s varying diets, for more concrete results.
“To explore the potential of probiotics to contribute to disease prevention in healthy people there is a major need for much larger, carefully designed and carefully conducted clinical trials,” Pedersen added.
“These should include ideal composition and dosage of known and newly developed probiotics combined with specified dietary advice, optimal trial duration and relevant monitoring of host health status.”
Their findings are published in the online journal Genome Medicine.