On Nutrition
As I mentioned in last week’s column, the human gut microbiome is both a thriving area of research and big business in the venture capital, Silicon Valley startup arena. This has resulted in some misinformation, including promises that this diet or that product will help you achieve a “healthy” gut microbiome. But here’s the problem — it’s still unclear what exactly constitutes a healthy gut microbiome.
To recap, your gut microbiome is the community of bacteria and other microorganisms that live in your large intestine, plus their genes and molecules they secrete. While it’s true that the gut microbiome influences our overall health in profound ways, it’s false that if you want to be healthy, there’s one specific population of microbes you should try to encourage. If nothing else, the fact that human gut microbiomes vary based on geography is evidence of that.
We have trillions of microbes in our guts, and as much research as we have on the gut microbiome, scientists are still figuring out the full complexity of these microbial communities. So far, the definition of a “healthy” human microbiome has been based on very small studies that largely identify “healthy” or “not healthy” microbiomes based on the health of the participants they belong to. Not only have these studies not captured information on a wide variety of people, but there’s a bit of a chicken-or-the-egg situation going on. If someone is healthy and has what appears to be a healthy gut microbiome, are they healthy because they have a “healthy” gut microbiome, or do they have a healthy gut microbiome because they are healthy?
It’s generally thought that a more diverse gut microbiome is a healthier gut microbiome, largely because this diversity might help prevent several diseases. Resilience — your gut microbiome’s resistance to changes due to stress, illness, or other factors — was also deemed important. The newer consensus of what it means to have a healthy gut microbiome focuses not just on the health of your microbiome itself, but what your microbiome is doing for you. Function over form.
For example, you could have a diverse, thriving, resilient gut microbiome, but if that community contains abundant antibiotic-resistant bacteria, that isn’t the kind of diversity and resilience that’s helpful to you. On the other hand, if you have a diverse, resilient gut microbiota that’s consistently ticking all the health-promoting boxes — protecting the integrity of your intestinal wall and the immune system cells within, fermenting fiber to produce beneficial short-chain fatty acids, breaking down your food so you can extract essential nutrients, and efficiently producing certain vitamins, such as vitamin K and many of the B vitamins — then that is helpful to you.
Again, it’s about functionality, and a functional, health-promoting gut microbiome isn’t dependent on a single “ideal” microbe population. And that’s good news. So with no clear target to aim for, what can you do if you want to support your own gut health? The baseline recommendation, based on research from the American Gut Project, is to add more plant foods to your diet — both for the fiber and the nutrients — and to also increase the weekly diversity of fruits and vegetables in your diet. So if you find you’re in the rut of buying and eating the same few fruits and veggies week after week, can you mix it up a bit? Can you add a different fruit to your smoothies? Add some different leafy greens, and maybe extra chopped or sliced veggies to your salads?