What’s the link between diet and the gut microbiome?

If you have ever wondered about the connection between your diet and what lives inside you – your microbiome – then here is a chance to find out! CLINICAL TRIAL participants needed.

While science has rightly focused on minimising the number of harmful bacteria to improve food safety and prolong shelf-life, we often forget about other microbes that may be found in fresh produce like fruits and vegetables.

“We are all familiar with fermented foods like yoghurt which contain beneficial microbes, but we have now discovered that some fruit and vegetables can naturally contain more bacterial diversity than yoghurt” said the Head of Hudson Institute’s Microbiota and Systems Biology Research group, Associate Professor Sam Forster.

“Our laboratory has found a remarkable number of different bacterial species living in minimally processed foods,” A/Prof Forster said.

“If they survive food preparation, we may consume food-derived bacteria that could ultimately colonise our gut microbiome.”

A/Prof Forster leads a research team of microbiologists and dietitians who were awarded an NHMRC Ideas Grant in 2020, to investigate what happens to these food-derived bacteria after they are eaten and whether they can potentially provide health benefits.

Major shift in diet and the microbiome

Researchers previously believed that the nutrient composition of food (fat, protein, dietary fibre) had the most influence on the composition of the human gut microbiota, but that idea is starting to change.

Recent studies have shown that dietary changes can induce major shifts in the gut microbiome within 48 hours and these changes are related more to which foods are eaten, rather than their nutritional composition.

Different individuals can also experience different effects on the gut microbiota from consuming the same food type, indicating that live non-harmful (commensal) food microbes may be helping to shape the human colonic microbiome.

“A greater variety of microorganisms living in the gut is associated with reduced chronic disease risk, so eating a wide range of minimally processed foods containing high levels of live bacteria might be more beneficial for health than consuming sterile, ultra-processed packaged foods” said Dr Nicole Kellow, a research dietitian at the Monash University Department of Nutrition, Dietetics & Food.

Clinical trial – diet and the microbiome

In order to further investigate the eventual fate and function of food-derived bacteria, the team is recruiting 20 participants for an eight-week clinical trial.

All food and drinks will be provided for four weeks free of charge, with meals designed by Hudson Institute research dietitian, Dr Marina Iacovou and cooked by qualified chefs.

Dr Iacovou specialises in formulating meals for clinical trials, and says that participants will be required to collect regular stool samples throughout the study.

“The food provided by the research team will have a known bacterial content so we will be able to detect them in stool samples if they have survived in the intestinal tract,” she said.

This project is approved by Monash Health HREC RES-21-0000-602A.