Tiny Molecule Made by Gut Bacteria Could Cut Type 2 Diabetes Risk

A study led by researchers at Imperial College London (ICL) suggests that a compound made by gut bacteria could be important for the management and prevention of type 2 diabetes.

Trimethylamine (TMA) and type 2 diabetes: a microbial metabolite with potential

The molecule in question is trimethylamine (TMA). It is a common bacterial metabolite-one of the chemicals microbes naturally generate as they convert nutrients into energy and other building blocks.

Using human cell models and laboratory mice, the scientists found evidence that TMA may help shield the body from certain harms associated with a high-fat diet. In particular, it appears to reduce inflammation and enhance insulin response, two changes that together lower the risk of type 2 diabetes.

Testing TMA in high-fat diets, obesity and inflammation

Earlier studies had already hinted at links between TMA and insulin resistance, but TMA’s precise part in the biochemical “conversation” between gut microbes and their host had not been fully defined.

To address this, the team ran a series of experiments that screened individual metabolites and then assessed whether TMA could lessen the effects of high-fat diets in mice and in human tissues. Their results indicate that this abundant microbial chemical may disrupt parts of the chain connecting diabetes, obesity, and persistent low-level inflammation.

"This flips the narrative," says ICL biochemist Marc-Emmanuel Dumas. "We've shown that a molecule from our gut microbes can actually protect against the harmful effects of a poor diet through a new mechanism."

Choline, eggs and meat: how gut microbes produce TMA

TMA is generated when microbes in the gut break down choline, an essential nutrient present in foods such as eggs and meat. The researchers showed that raising choline levels in high-fat diets prevented some of the most damaging outcomes.

IRAK4, kinases and the microbiome’s signalling switches

Further work found that TMA inhibits the protein IRAK4, which would normally activate an inflammatory response when a high-fat diet is detected. Looking ahead, the same kind of protection might be achieved with drugs, limiting the amount of inflammation produced by diets high in fat.

The study also points to broader, meaningful implications: it demonstrates that the bacteria in our guts can release chemicals (such as TMA) that interact with and regulate kinases (such as IRAK4)-signalling switches involved in a wide range of biological pathways and processes.

"It's a new way of thinking about how the microbiome influences our health," says Dumas.

"Our work opens exciting possibilities with kinases as a new repertoire of targets accessible by microbiome-based therapeutic interventions in obesity and diabetes."

TMA, TMAO and cardiovascular disease: a surprising twist

TMA has previously been linked with cardiovascular disease, partly via the related compound trimethylamine N-oxide (TMAO). Against that backdrop, the suggestion that TMA itself may provide benefits to the body is an unexpected development.

"In view of the growing threat of diabetes worldwide and its devastating complications for the whole patient, including the brain and heart, a new solution is direly needed," says cardiologist and professor of medicine Peter Liu, from the University of Ottawa in Canada.

"Our team's work connecting Western-style foods, TMA produced by the microbiome, and its effect on the immune switch IRAK4, may open entirely new ways to treat or prevent diabetes, a known risk factor for heart disease."

What comes next for this early-stage research

This work is still at an early stage, and the findings will need to be reproduced in human participants over longer timeframes. If confirmed, it could point towards a fresh approach to managing insulin resistance that can progress to type 2 diabetes.

The research has been published in Nature Metabolism.