Newsworthy: previous dietary experience and gut microbial exchange with other individuals have implications on affecting a person’s response to new diets. 

EATING HEALTHILY is at the top of the list for many of those setting New Year’s resolutions. However, changing your diet could be more complicated than you think—researchers have found that your previous dining experience could impact your new diet efficiency through gut microbiota. This might explain why so many New Year diets don’t work.

Gut Microbiota: Our Native Flora by Micah Lidberg

But hold on… researchers also found that if there’s another person in your household who already eats healthily, you might have a better chance of
success. The reason might be that their gut microbes are influencing your dietary practices, according to a recent study published in Cell Host & Microbe. The implications suggest possibilities in developing probiotics that simulate a similar healthy gut microbiota community to support your dietary changes.

The study conducted by Dr. Jeffery I. Gordon, director of the Center for Genome Sciences & Systems Biology at Washington University in St. Louis and his team, was interested in if and how, gut microbiota—the tens of trillions of microorganisms in our intestine—affect, and are affected by, our dietary practices. These tiny microbes usually live happily within our gut and pay the “rent” to our body by helping digest food and synthesize essential vitamins such as vitamin B and K. Gut microbiota also function as an armor for our intestine to defend against other aggressive microorganisms.

Previous studies suggest that typical unrestrictive American diets might result in a weakened gut microbiota, which can compromise overall health. To put this idea to the test, Dr. Gordon and his colleagues genetically analyzed fecal samples from 34 adult donors who have maintained healthy diets and 198 donors who have typical unrestrictive American diets. The results indicated that people who practice healthy diets bear a significantly richer and more diverse gut microbiota than people who do not, including many microbes that seem to only be associated with a healthy diet.

Dr. Gordon’s team also found that when transferring the fecal microbiota from the unrestricted-diet individuals to germ-free mice, these mice were not able to adjust to a new diet as easily as their counterparts, who were received healthy-diet microbiota. Based on these results, the researchers suggest that reduced bacterial diversity caused by the prior dietary practice can influence our body’s response to a new diet.

However, there is still hope in the story of gut microbiota. Although each of us has our unique collection of gut microbiota, it is never isolated or static. Instead, we are constantly shedding our microbiota—picture that we are all surrounded by a cloud of our microbes. Our microbiota and other individuals’ microbiota come together and make up a large microbial community called a metacommunity. Within the metacommunity, we continuously exchange our microbes with people who live in close association with us.

In a follow-up experiment, Dr. Gordon and his colleagues created an artificial metacommunity by placing together mice harboring unrestricted-diet microbiota and mice with healthy-diet microbiota to further understand whether promoting bacterial dispersal between these mice could affect their responses to diet change. Interestingly, it turned out that mice with unrestricted-diet microbiota, which previously showed inefficient response to the new diet, have significantly improved their digestive performance by being in close proximity to mice with healthy-diet microbiota.

These findings suggest important implications for how dietary practices can be prescribed for success. However, since this study was primarily on mice, it will take more research to determine the health outcomes of the interpersonal microbiota exchanges for humans. The researchers believe that with a richer understanding of how humans exchange microbiota with other individuals and its effects on health, one day our concept of “social” diseases will be refreshed to incorporate perspectives of metacommunity dynamics in public health.

For many people, switching a diet can be challenging. Therefore, uncovering microbial potentials and ensuring a positive response to new diets for our body have always been a major goal of these studies. The hope in the near future is to be able to identify microbes that are associated with different dietary practices and use these microbes to make probiotic products in order to enhance people’s digestive responses to their new diet.

After all, switching to a healthy diet is always a smart choice for your health!


It’s Not Yet Clear How to Boost the Microbiome. But Diet Is the Best Bet” – TIME