How Feces Can Improve Our Understanding of Nutrition and Health

Saturday - April 29 2023, 02:36 UTC - 1 year ago

Analyzing feces has become a useful tool towards understanding nutrition and health. Fecal samples can indicate whether people have eaten individial foods, and studies to improve nutrition research that try to figure out how certain foods affect our health usually rely on volunteers to keep food diary which is inaccurate and incomplete. This study showed that microbes found in feces can indicate food consumption with 80-87% accuracy.

Feces are good for so much more than flushing.

Yes, our waste contains the stuff that our bodies are generally trying to get rid of. But it can also provide insight into our gut microbiomes and how they influence our health. And we’re getting closer to understanding the impact of individual foods.Scientists are getting better at collecting and making sense of this data. This week, I came across a fascinating study in which researchers tried to tell whether people had eaten individual foods—avocados, walnuts, broccoli, and others—just by analyzing their poo. For some of these foods, accuracy was upwards of 80%.

The scientists behind the work want to use this approach to aid research. But we could potentially use the same approach to improve our health. Other researchers hope to use stool analysis to provide people with personalized, microbiome-based diet advice, for example.But when it comes to the details, we’re still figuring out exactly how the relationships between diet, microbiome, and health work. Alterations in the microbiome have been linked to multiple diseases, including irritable bowel syndrome, Parkinson’s disease, and arthritis, to name a few.

Berry and her colleagues are trying to work out exactly how diet might influence the microbiome and, in turn, people’s health. And to find out, they’re turning to poo. As part of ongoing research, the team is collecting fecal samples, as well as dietary information and health data, from over a thousand volunteers.

It was tricky to find specific bugs associated with specific foods, but the presence of one particular microbe was a strong indicator of whether or not a person had been drinking coffee. Basically, if you’re a coffee drinker, a microbe in your feces will give you away.

The new study, by Hannah Holscher at the University of Illinois at Urbana-Champaign and her colleagues, takes a slightly different approach. Here, the team looked at fecal samples from volunteers who ate set amounts of specific foods on a daily basis. And rather than look at the presence of microbes themselves, Holscher’s team looked for metabolites—the chemicals microbes produce when they break down food.

Again, it was tricky—but the team was able to tell whether people had eaten almonds, broccoli or walnuts with 80 to 87% accuracy, depending on the food. The study was published online at the preprint server bioRxiv and has not yet been peer-reviewed. But it builds on similar work the team published last year.

Holscher’s team hopes to improve nutrition research. Studies that aim to figure out how certain foods affect our health usually rely on volunteers to keep food diaries. They’re a pain to maintain, and they’re usually inaccurate or incomplete. Analyzing a person’s poo instead could one day provide a painless alternative.

In theory, scientists might one day be able to provide diet recommendations designed to target specific microbes, and potentially guide the production of specific metabolites that might influence our appetites, metabolism, or even our moods, says Leeming.

"There’s so much you can learn from someone’s poo," she says.