Amid the increasing rise of probiotic use in Western society, a recent journal article asks whether we should evaluate the products’ safety with a little more scrutiny.
Probiotics are popular, but what does the evidence say?
For millennia, humans have consumed foods rich with live bacteria.
Yogurt, for instance, dates back to at least 5000 B.C., and in Korea, kimchi — fermented vegetables — has also been consumed for thousands of years.
Today, however, live microorganisms are added to a range of products advertised as providing a wide array of medical benefits.
Creative marketing and a general fascination for gut bacteria have combined to create a huge market for probiotics.
Perhaps surprisingly, to sell a product that contains live microorganisms there is no legal requirement to provide evidence that it works or, importantly, that it is safe.
An article published this week in JAMA Internal Medicine argues that this is a dangerous state of affairs. The piece was written by Dr. Pieter A. Cohen from the Cambridge Health Alliance at the Harvard Medical School in Boston, MA.
The state of the evidence
Dr. Cohen begins by outlining the proven benefits of probiotics. For instance, Saccharomyces boulardii has been shown to help treat some types of diarrhea in children and reduce recurrence of Clostridium difficile infections in adults.
In spite of the specific cases mentioned, he argues that the strains used in foods and supplements have not been proven to benefit health and neither have they been shown to be safe.
Manufacturers claim that probiotics help maintain respiratory, cardiovascular, reproductive, and psychological health. However, Dr. Cohen writes that “despite the advertised indications, there are no large, long-term clinical trials proving that probiotics offer clinical benefits for people who are already healthy.” He continues:
“[W]idespread use, particularly among people who are healthy, has greatly outpaced the science.”
For instance, a comprehensive review of relevant literature published earlier this year concluded that “[t]he feasibility of probiotics consumption to provide benefits in healthy adults requires further investigation.”
In other words, there may be benefits, but the evidence simply does not exist to definitively say either way.
Despite this, manufacturers are legally permitted to tell consumers that their products “support the immune system” or “boost digestive health.” Perhaps even more worryingly, they are not required to add information regarding potential adverse effects.