Step into the grocery aisle and you’ll find a huge range of “probiotic” products, advertising billions of beneficial bacteria with each cup of yogurt or bottle of kombucha.
But what exactly have these commercial bacteria been proven to do? Maybe less than you think.
The important thing to remember is that probiotics aren’t all the same. “The reality is there are hundreds, thousands, who knows how many strains of bacteria that are good for us,” said Mary Scourboutakos, a Ph.D. in nutrition who has researched common probiotics in Canada.
It’s not a question of whether bacteria are good or bad, she said.
“It’s, which ones are specifically good for us, and which ones are good for certain purposes or certain benefits?”
Different bacteria do different things, so looking for just a “probiotic” isn’t exactly helpful. You have to know what benefit specifically you’re looking for.
A good place to start, according to Gregor Reid, the endowed chair in human microbiome and probiotics at the Lawson Health Research Institute and a professor at Western University, is a table that researchers have put together examining probiotic products in Canada and the science behind them.
It shows that certain strains of bacteria, like one found in DanActive yogurt, can help to prevent diarrhea associated with antibiotic use, for example. There’s also human research on some strains of bacteria that can help with constipation, irritable bowel syndrome, and prevent some common infectious diseases.
But no bacteria does everything.
“It’s like saying that all drugs are the same. You can’t say that. You have to be much more specific. What is it you want to achieve? What are you concerned about? Which products should therefore be chosen, based on the evidence so far?” said Reid.
Some of that existing scientific evidence can be “tricky” though, said Scourboutakos. In her research, she found that a lot of studies tested much higher doses of bacteria than you might find in a typical serving of yogurt.
Not only that, but because everyone has a unique mix of gut bacteria, people might need different doses in order to see an effect, she said.
More strains of bacteria aren’t necessarily better either. “Say you put three strains in a product. There’s no guarantee that when a person eats that product that those three strains are going to be equally represented. They’re living things. One might be growing faster than the others. One might outcompete the other.”
“When you put 11 strains in one product, you don’t even know what you’re consuming at the end of the day.”
Gut hype
Timothy Caulfield, Canada research chair in health law and policy at the University of Alberta, thinks that the current craze for probiotics is due to “gut hype.”
“It’s one of those areas right now that I thought was tremendously hyped and that people are leveraging the legitimate science that’s going on in this area in order to sell what I think are largely unproven products.”
A lot of products sold in supermarkets are sold under very general claims of promoting good health, which makes them difficult to check or regulate, he said. And while there is “genuinely exciting science” being done on the microbiome – the mix of bacteria that live on and in every person – and its effects on health, he thinks people should remain skeptical about probiotic products until more research is done.
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However, Scourboutakos and Reid both recommend including fermented foods or probiotics as part of your regular diet.
“I do think it is a staple of the human diet,” said Scourboutakos.
But probiotics aren’t the only way to promote good gut health, she said. Your overall diet also plays a huge role.
“The most important thing you can do for gut health is to eat fruit, vegetables and fibre. Because we already have good bacteria in us and when we eat fruit, vegetables and fibre, we promote the growth of that good bacteria that’s living in us.”
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