Scientists have long known that a high-salt diet can lead to cardiovascular disease, but a new study from MIT has found that microbes living in the human gut may help protect against the effects of a high-salt diet.

 

In collaboration with German-based researchers, the MIT team found that in both mice and humans, a high-salt diet shrinks the population of a certain type of beneficial bacteria, causing pro-inflammatory immune cells (called Th-17 cells) to grow in number. These immune cells have been linked with hypertension, although the exact mechanism of how they contribute to the condition is not yet known.

 

Probiotics as part of a healthy diet

 

The researchers further showed that treatment with a probiotic could reverse these effects, but they caution that people should not interpret the findings as licence to eat as much salt as they want, as long as they take a probiotic. “I think, certainly, there’s some promise in developing probiotics that could be targeted to possibly fixing some of the effects of a high-salt diet, but people shouldn’t think they can eat fast food and then pop a probiotic, and it will be cancelled out,” said Eric Alm, Director of MIT’s Center for Microbiome Informatics and Therapeutics, and Professor of Biological Engineering and Civil and Environmental Engineering at MIT.

 

It is still unclear exactly how Th-17 cells contribute to the development of high blood pressure and other ill effects of a high-salt diet. “We’re learning that the immune system exerts a lot of control on the body, above and beyond what we generally think of as immunity,” Prof. Alm says. “The mechanisms by which it exerts that control are still being unravelled.”

 

The researchers hope that their findings, along with future studies, will help to shed more light on the mechanism by which a high-salt diet influences disease. “If you can find that smoking gun and uncover the complete molecular details of what’s going on, you may make it more likely that people adhere to a healthy diet,” he suggested.

 

Exploring the connections

 

Professor Alm and others at the Center for Microbiome Informatics and Therapeutics are also studying how other dietary factors such as fibre, fat, and protein affect the microbiome. They have collected thousands of different strains of bacteria representing the most abundant species in the human gut, and they hope to learn more about the relationships between those bacteria, diet, and diseases such as inflammatory bowel disease.

 

The research was funded by the German Center for Cardiovascular Research, the MIT Center for Microbiome Informatics and Therapeutics, and the MetaCardis consortium.