They are the rage these days—probiotics that promise to ease an upset stomach, mitigate the disastrous effects of antibiotics on the microbiomes in our gut and, promise good gut health, in general.
However, according to a new article published in the journal Lancet, we are better off not wasting our money on probiotics (highly concentrated supplements of the "good bacteria").
The article quotes two recent studies from the journal Cell, where researchers found that instead of helping the gut bacteria, probiotics actually did not help those who had them after a course of antibiotics.
Studies that investigated the recovery of the gut microbia after antibiotics found that probiotics might "perturb rather than aid the process". The probiotics rapidly colonised the gut but they also prevented the normal microbes from repopulating for up to five months, the study found.
Besides, the "gut colonisation" occurred in highly individualised patterns—while some people's gastrointestinal tracts rejected probiotics, others allowed the colonisation by the probiotic strain. The Lancet article also cited results of two large scale trials reported in the New England Journal of Medicine that suggest that probiotics did not prevent the development of moderate-to-severe gastroenteritis. In the trials, scientists used probiotics that are available over the counter in North America.
Results of these trials showed there was no significant difference from placebo (versus probiotics) in the duration of diarrhoea and vomiting, or the number of unscheduled health care visits.
Though the results of these studies cannot be generalised to other probiotic strains or preparations, they do show that there's some way to go in elucidating which probiotics might provide benefits in which clinical settings, the article says.
At the heart of the matter is the fact that all individuals have a unique gut microbiome. So, the effects of different bacteria on different people are likely to be highly variable, and probiotic use may need to be "personalised" for optimal benefits. The probiotic products available commercially might not contain the correct strains or quantities of bacteria to provide benefits.
According to the Lancet article, 3·9 million people in the US regularly take probiotic supplements. The promised benefits range from "improved digestion and immune function to improved mental health and prevention of heart disease". However, there isn't much evidence for these benefits, the authors of the article caution. Besides, since probiotics are often sold as supplements, manufacturers in many countries are not required to provide evidence of their safety and efficacy to regulatory bodies.
While probiotics are mostly safe, the authors of the article point to concerns such as the risk of contamination, possibility of fungaemia or bacteraemia (particularly in immune-compromised, elderly, or critically ill individuals), small intestinal bacterial overgrowth, and antibiotic resistance.
So, if probiotics are a waste of money, what is the key to good gut health? The old fashioned diet, that includes diverse food items, each of which has properties that aid in keeping the gut microbiome healthy.
