Scientists are studying microbes inside the human body to develop new drugs for heart disease. Dr. Ambuj Roy said, “There is data to show that only 20% of people who should be on a statin, take statin in the long term.” Researchers now hope these gut bacteria offer better treatment options.

In mice engineered to develop atherosclerosis (fatty plaque in artery walls), the live bacterium shrank plaque by about a third, and the acid on its own halved it. In blood and stool from more than 200 donors, people with high blood fats had less of the acid, and those with heart disease carried fewer of the bacterial genes that make it.

Statins already work by the same route. The difficulty, said Dr Ambuj Roy, professor of cardiology at the All India Institute of Medical Sciences (AIIMS), Delhi, is adherence. “There is data to show that only 20% of people who should be on a statin, take statin in the long term,” he said. That – and statins’ plateau effect where they don’t help beyond a particular level -- is why science has been looking for alternatives.

First evidence in patients

Both chains so far rest on mice, but in cancer the gut’s influence on treatment has already been tested in patients. In a trial reported in Nature Medicine in January, researchers gave patients capsules made from screened donor stool alongside immunotherapy. Of 20 people with lung cancer, 80% responded, against the 39–45% typical with immunotherapy alone. Of 20 with melanoma, 75% responded, against a typical 50–58%. The trial, however, had no comparison group, and a randomised trial across Canada is now testing whether the gains hold.

The capsules carry a donor’s whole gut community. A more refined approach uses defined mixes of laboratory-grown strains. Dr Govind Makharia, professor of gastroenterology at AIIMS, Delhi, expects mixes to be the norm. “A single bacterium doesn’t work generally; it has to be a cocktail of bacteria,” he said.

The Indian gut question

B. uniformis is “almost there in every human gut”, including Indian ones, Makharia said. In August, though, researchers at the National Centre for Cell Science in Pune found 14 new gut bacterial species in eight tribal communities, and found that Indian strains differ genetically from Western ones. Whether Indian B. uniformis makes as much pentadecanoic acid has not been measured.

For the cholesterol finding, Roy said he is watching for the studies in humans now.