Don't judge a food by its label: Individual gut responses to foods found to vary

13 Jun 2019 --- Foods that look the same on nutrition labels can have vastly different effects on our microbiomes, a recent study has found, further expanding knowledge on the intricate relationship between gut bacteria and overall health. The impact of leafy greens on the gut, for example, can be vastly different from the influence of carrots, despite their nutritional profiles being similar. The researchers have now developed a new approach for measuring and comparing the different foods – based on the gut.

“Nutrition labels are human-centric,” says senior author Dan Knights of the Department of Computer Science and Engineering and the BioTechnology Institute at the University of Minnesota. “They don’t provide much information about how the microbiome is going to change from day to day or person to person.”

In the study, the investigators enrolled 34 participants to record everything they ate for 17 days. Stool samples were collected daily and shotgun metagenomic sequencing was performed. This allowed the researchers to see at a very high resolution how different people’s microbiomes, as well as the enzymes and metabolic functions that they influence, were changing from day to day in response to what they ate. The study provided a resource for analyzing the relationships between dietary changes and how the microbiome changes over time.

A new nutritional system?
“We expected that by doing this dense sampling – where you could see what people were eating every single day and what’s happening to their microbiome – we would be able to correlate dietary nutrients with specific strains of microbes, as well as account for the differences in microbiomes between people,” Knights says. “But what we found were not the strong associations we expected. We had to scratch our heads and come up with a new approach for measuring and comparing the different foods.”

What the researchers observed was a much closer correspondence between changes in the diet and the microbiome when they considered how closely foods were related to each other rather than simply comparing their nutritional content. Following this, the researchers developed a tree structure to convey the statistical information of closely related foods.

Two people in the study consumed nothing but Soylent, a meal replacement drink that is popular with people who work in technology. Although it was a very small sample, data from these participants showed variation in the microbiome from day to day, suggesting that a monotonous diet does not necessarily lead to a stable microbiome.

“The microbiome has been linked to a broad range of human conditions, including metabolic disorders, autoimmune diseases and infections, so there is strong motivation to manipulate the microbiome with diet as a way to influence health,” Knights concludes. “This study suggests that it’s more complicated than just looking at dietary components like fiber and sugar. Much more research is needed before we can understand how the full range of nutrients in food affects how the microbiome responds to what we eat.”

The microbiome: A complicated picture for health?
Digestive health is an ongoing discussion and science continues to link a healthy microbiome to nearly every facet of health. For example, research has pointed to a relationship between the gut and the gastrointestinal tract and the central nervous system, known as the “gut-brain axis.” There is also mounting evidence linking imbalances in the microbial species that make up the gut microbiome to a number of health problems including allergies, autoimmune disorders and psychiatric mood disorders. Probiotics have even been flagged as a potential avenue of treatment to alleviate bipolar and other psychiatric mood disorders, such as depression. 

A wealth of investments have also been donated to the space to accelerate understanding and innovation. In March, European venture capital firm Seventure Partners completed the first closing of its second dedicated fund focused on the microbiome and health, nutrition and digital/connected health sectors with a target for the final close of over €200 million. 

Also earlier this year, The Master Project, which aims to harness microbiome knowledge and DNA sequencing to boost food chain sustainability, received EU funding of nearly €11 million. 

 The continuous media reporting on gut health has also helped stimulate consumer interest in probiotics. The gut health platform offers a wealth of opportunities to formulators, but due to regulatory demands, research data gaps and increasing consumer scrutiny, a clear view of how to navigate this space is vital.