Many people turn to the internet with health questions, but how reliable is the information you find? When it comes to probiotics, a new study urges caution.
The research found that of 150 websites that came up with a search of probiotics, most were commercial sites, hoping to sell a product. Others were news sites or health portals (providing links to other sites). Many of these sites mentioned potential benefits of probiotics, though not all had scientific evidence to back up those claims. And just one in four of the websites mentioned any potential side effects from taking probiotics.
"This study demonstrates that a number of online claims on the health benefits of probiotics are not supported by scientific evidence," said study co-author Dr Michel Goldman, a professor of immunology at the Universite Libre de Bruxelles in Belgium.
Probiotics are "good" bacteria found in yogurt and other fermented foods and in dietary supplements, according to the US National Center for Complementary and Integrative Health. Some of these bacteria are also found naturally in the human body. They may help digest food, fight germs that can cause disease, or produce vitamins.
Some broad claims
"Probiotics can clearly be helpful in the management of infectious diarrhoea, in pregnant women with gestational diabetes, and as an adjunct to food allergy desensitisation therapy," Goldman said. He added that probiotics might also be helpful for the skin condition eczema and for some urinary or genital infections in women.
But his team saw some broad claims online about probiotics' benefits, such as being beneficial in treating cancer. There's no scientific evidence to support those claims.
For the study, Goldman and his colleagues looked at the first 150 pages brought up by Google in response to a search for "probiotics". They reviewed the information on these pages for reliability and searched a large database of clinical trials for evidence supporting those claims.
One bright spot was that Google appears to prioritise more reliable sources of information over commercial websites.
Still, consumers should be wary of health information they get online.
Less reputable information
"Consumers should look whether there is scientific information published in peer-reviewed medical journals supporting claims to probiotics and over-the-counter health products that are not regulated as rigorously as prescription drugs. They should discuss with their doctors, the benefits they can expect from probiotics," Goldman said.
Dr Melinda Ring, executive director of the Osher Center for Integrative Medicine at Northwestern University in Chicago, said she wasn't surprised by the findings.
"This is a big problem in the natural product and dietary supplement area. There's a preponderance of less reputable information from sales and commercial sources," said Ring, who wasn't part of the research.
"People really need to look at the claims websites are making. Are they promising unrealistic cures? Are they referencing scientific data?" she said.
One area where probiotics may be helpful is in maintaining the body's natural balance of beneficial bacteria – the gut microbiome. "We know the human microbiome is incredibly important to our health and the development of disease, but we're just in the infancy of understanding how to manipulate the microbiome," Ring said.
If you're interested in improving your gut's microbiome, the first place to start is improving your diet, because what you eat is also food for your microbiome, Ring said. Focus on vegetables, fruits and whole grains.
The most trusted sources
A number of foods have probiotics, such as yogurt and fermented foods. But sometimes the probiotics that occur naturally in foods can be destroyed by processing and preserving. Ring recommended looking for "live cultures" on the packaging.
If you take probiotic supplements, she suggested sticking with reputable brands, and perhaps taking more than one product to make sure you're getting a diversity of probiotics.
Andrea Wong is senior vice president of scientific and regulatory affairs for the Council for Responsible Nutrition (CRN), which represents the supplement industry. She said that research demonstrates that probiotics are safe and have health benefits.
"When it comes to reliable information on probiotics and other dietary supplements, doctors and other health care practitioners are the most trusted sources. CRN encourages consumers to be smart shoppers and practise due diligence when looking for dietary supplement information," Wong said.
The findings were published in Frontiers in Medicine.
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