Ask the doctors: Eating less meat can improve gut microbiome
Q: I read about a study that says it's possible for someone who eats meat to have a gut that's as healthy as someone who is vegan. I know your gut microbiome is an important part of good health, but I'm just not cut out to be a vegan. I'd like to know more about that research.
A: The trillions of microbes that live in our guts have been grabbing headlines since the early 2000s. That was the start of a cascade of research that revealed their far-reaching influence on almost every aspect of health and well-being.
We now know that the gut microbiome has a profound effect on more than digestion. It also affects metabolism, immunity, disease risk, longevity and even mental and emotional health.
Thousands of studies have focused on the gut's complex ecosystem. The plant-based diets of vegans and vegetarians have a lot of different food for microbes in the gut. These diets encourage the growth of diverse and helpful communities. That's key.
One of the byproducts of microbial digestion is molecules that act as chemical messengers. These compounds help regulate metabolic, nutritional and immune responses. They also have a direct effect on brain activity.
Eating a lot of meat, by contrast, has been linked to less optimal gut profiles. Possible links include less diversity in the microbial communities and imbalances between beneficial and nonbeneficial species. Bacterial activity linked to local and systemic inflammation is another likelihood.
But a group of researchers from Italy and England had more nuanced findings. They wanted to know how various diets would affect gut microbiome populations. Their research, published last year in the journal Nature, had good news for meat eaters like you.
The researchers created a pool of data from more than 21,000 people from Italy, the United Kingdom and the United States. These people had taken part in a gut microbiome study before. The participants had kept detailed food diaries. They also gave stool samples, which had genetic analysis. Researchers used both the genetic and dietary data. They compared how the various diets affected the health and diversity of the gut microbiome.
As in previous research, vegans and vegetarians had more markers linked to better health. Meat eaters' guts hosted bacteria associated with inflammation. The surprise came when looking at the profiles of “good” bacteria in the gut microbiomes of meat eaters. Those who also ate a lot of varied plant-based foods had good bacteria that mirrored the vegans.
Whether the good bacteria balance out the meat-related bacteria is not known. But for omnivores wishing to optimize gut health without giving up meat, this suggests a path forward. Eat plenty of fresh vegetables, leafy greens and fruit. Legumes, grains, seeds and nuts are also important.
When eating meat, choose lean, healthy cuts. Treat meat as a condiment rather than a main course. Studies show the gut microbiome is highly responsive to dietary changes. Flip the diet ratio from meat to veggies and you can harness that for your own improved health.
• Dr. Eve Glazier is an internist and associate professor of medicine at UCLA Health. Dr. Elizabeth Ko is an internist and assistant professor of medicine at UCLA Health. Send your questions to askthedoctors@mednet.ucla.edu.
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