The trillions of microscopic bacteria that live in our gut play a huge role in our health.
TOM LEACH / SCIENTIFIC PHOTO LIBRARY
We often hear talk about how something is good for our microbiome and, in turn, good for our body. health. But it wasn't entirely clear what a healthy gut microbiome consists of. Now, a study of more than 34,000 people has brought us closer to understanding the combination of microbes that reliably signal that we have low inflammation, good immunity and healthy cholesterol levels.
Your gut microbiome may influence your immune systemspeed aging And your risk of poor mental health. Despite the abundance of home tests that promise to reveal your gut structure, their usefulness is debatedbecause it is difficult to determine what a “good” microbial mixture is.
Previous measures mainly focused on species diversity: the more bacteria, the better. But it is difficult to identify the specific communities of interacting organisms that are involved in a particular aspect of our health because microbiomes vary greatly from person to person.
“There is a very complex relationship between the food we eat, the composition of our gut microbiome and the impact that the gut microbiome has on our health. The only way to try to map these connections is to have large enough sample sizes,” says Nicola Segata at the University of Trento in Italy.
To create such a map, Segata and colleagues assessed a dataset of more than 34,500 people who took part in the PREDICT program in the UK and US, run by microbiome testing firm Zoe and compared the results with data from 25 other cohorts from Western countries.
Of the thousands of species found in the human gut, researchers focused on 661 species of bacteria that were found in more than 20 percent of Zoe study participants. They used this to identify the 50 bacteria most associated with markers of good health (measured using markers such as body mass index and blood glucose levels) and the 50 most associated with poor health.
The 50 species of “good bugs,” 22 of which are new to science, appear to influence four key areas: cholesterol levels; inflammation and immune health; distribution of fat in the body; and blood sugar control.
Participants who were considered healthy because they had no known medical conditions had about 3.6 more of these types than people with the condition, while people at a healthy weight had about 5.2 more of these types than people with obesity.
Researchers suggest that good or bad health outcomes may be linked to the vital role that the gut microbiome plays in releasing chemicals involved in life processes. cholesterol transport, reduction of inflammation, fat metabolism And insulin sensitivity.
In terms of the specific species that were present, most of the microbes, both “good” and “bad”, belong to the class Clostridia. In this class, species of the family Lachnospiraceae occurred 40 times, of which 13 had a beneficial effect and 27 had an unfavorable effect.
“The study identifies groups of bacteria that can be further studied for their potential positive or negative effects. [on] health conditions such as high blood glucose or obesity,” says Ines Moura at the University of Leeds, UK.
The relationship between these microbes and diet was assessed using nutrition questionnaires and data recorded in the Zoe app, where users are advised to consume at least 30 different plants per week and at least three servings per day of fermented foods, with an emphasis on fiber and not too many ultra-processed options.
The researchers found that most of the germs were either associated with generally healthy people. diet and better health, or with worse nutrition and poor health. But 65 out of 661 microbes did not fit.
“These 65 bacteria are evidence that the picture is still more complex than what we saw,” says Segata, who also serves as Zoe's consultant. “The effects may depend on the other microbes present, the specific strain of bacteria, or the specific diet.”
This sorting of “good” and “bad” bacteria allowed the researchers to create a ranking scale from 0 to 1000 to assess the overall health of a person's gut microbiota, which is already being used as part of Zoe's gut health tests.
“Think of a healthy gut microbiome as a community of chemical factories. We want a large number of species, we want more good ones than bad, and when you get that, you'll produce really beneficial chemicals that have effects throughout the body,” says a team member. Tim Spector at King's College London, co-founder of Zoe.
However, this does not mean that the ideal healthy gut microbiome has been defined. “Defining a healthy microbiome is challenging because the composition of the gut microbiome is influenced by diet, but it can also change due to environmental factors, age and health conditions that require long-term treatment,” says Moura.
“We really need to think of our body and our microbiome as two complex systems that together make up one even more complex system,” Segata says. “When you change one thing, the effect changes a little and that's it. Understanding what is cause and effect can be very difficult in many cases.”
Larger studies are needed to identify these connections and cover a larger portion of the world's population, Segata says. However, once we establish a baseline of your health and microbiome, it will be possible to recommend specific foods to improve your gut bacteria, he says.
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