Postbiotic supplement boosts body’s own GLP-1 and weight loss

A daily “postbiotic” supplement containing dead bacteria may help people lose weight by boosting the levels of GLP-1 hormone in the body, according to a small trial. The findings suggest it could provide a cheaper, more convenient alternative to drugs like semaglutide – or help to maintain weight loss after stopping these medications. GLP-1 drugs, which mimic an appetite-suppressing hormone made by the intestine, are widely used for weight loss. But about half of people who take them for this purpose in the US stop within a year due to high costs, drug shortages and side effects such as nausea, vomiting and stomach pain. This has fuelled interest in supplements, often containing bacteria or fibre, that claim to promote weight loss at a lower cost and with fewer side effects. Some of these are purported to boost the body’s production of GLP-1. Advertisement But most supplements haven’t been rigorously tested in randomised controlled trials, says Simon Cork at Anglia Ruskin University in the UK, who wasn’t involved in the study. Chariharth Vivek Lal at the University of Alabama at Birmingham and his colleagues recruited 80 adults in the US who were overweight or had obesity. They randomly assigned half the participants to take a daily supplement containing a dead bacterium called Lactiplantibacillus plantarum, which commonly enters the gut via fermented foods such as kimchi and olives. Prior studies suggest dead L. plantarum can boost levels of bacteria, such as Lactobacillus, that produce short-chain fatty acids. At high-enough levels, these can stimulate intestinal cells to release GLP-1. The supplement, sold as ResM, also contains vitamin D3, vitamin B12, white mulberry leaf, fenugreek seed extracts and chromium picolinate, a compound purported to improve metabolism. The remaining participants took placebo pills. After two months, the participants in the supplement group reported that they had lost 2.6 kilograms, or 3 per cent of their body weight on average. In contrast, those in the placebo group gained half a kilogram on average. The placebo group experienced more mild side effects, such as nausea and bloating, than those taking the supplement. Further analysis revealed that ResM seemed to more than double GLP-1 levels in the blood, suggesting this hormonal effect reduced food intake to enable weight loss, the team wrote in the paper. GLP-1 levels didn’t change in the placebo group. The results suggest ResM could offer a cheaper way to lose weight, or maintain weight loss, than GLP-1 drugs, with fewer side effects, says Cork. “If you can get a safe [supplement] that presumably is going to be cheaper that causes a good amount of weight loss long term, that could be an advantage.” But it is unclear exactly how the various supplement components contributed to the weight loss, says Cork. Other limitations are that self-reported weight measurements are prone to error, and participants reported their own adherence to taking the pills, which may not be accurate, he says. These limitations, paired with the small size of the study, mean ResM cannot be reliably compared to approved GLP-1 drugs, which have been more rigorously trialled in hundreds of people over much longer periods, says Cork. Larger studies in which hundreds of participants taking ResM are weighed on standardised scales – and where their adherence to taking the pills is checked – are needed to verify the results, he says. “If it does start to show really good weight loss at a larger scale, I think that’s a really exciting avenue.” Such studies could explore whether taking ResM for longer achieves even greater weight loss, says Cork. The weight loss seen in the study falls short of the 5 per cent reduction in body weight that is linked to substantial health benefits. “That’s when you start to see big changes in things like blood pressure and metabolism,” he says. For now, Cork recommends that people consult their doctor before trying any supplements for weight loss.