Years ago, before “microbiome” became a health buzzword, I began reporting on research showing the importance of healthy probiotic bacteria in your gastrointestinal (GI) tract—otherwise known as the GI microbiome.
Since then, it’s been well-established that a healthy GI microbiome is critical for a healthy immune system, which helps you fight off virtually every chronic disease. (Not to mention infections and viruses like COVID-19.)
So it makes sense that two new, cutting-edge studies have found that genetic sequencing of the microbiome can not only determine whether you have a disease, but can even predict your risk of dying within the next 15 years.
How the GI microbiome governs immunity
I’ve written before that the bulk of our immune cells are in our GI microbiomes. And there’s evidence that a healthy microbiome helps balance the immune system. This is crucial because an unbalanced immune system can harm the body’s organs and tissues.
We’ve actually seen this with COVID-19. Some reports suggest that an overreacting, unbalanced immune system has damaged lung tissues in people with the virus—contributing to respiratory failure and even death.
So while the immune system needs to protect us from infections with dangerous microbes, it also needs to coexist peacefully with probiotic bacteria and tissue cells in the body. Which is why it’s so important to have a balanced immune system—one that’s relaxed when there are no invaders, but jumps into action when there are.
Taking all of this into account, it makes sense that researchers have discovered that the mix of probiotics in our GI microbiomes can reveal the presence of many diseases better than looking at our own genes.
What your gut tells you about disease
Harvard researchers evaluated 47 studies examining the links between the GI microbiome and common diseases like asthma and hypertension. They discovered that the genetic signature of gut microbes was 20 percent more accurate than full human genome sequencing for distinguishing between healthy and unhealthy people.1
They also found that microbiome analysis was 50 percent better than genome sequencing at predicting whether or not someone had colorectal cancer.
These findings jibe with previous evidence that both genetics and your environment help determine your risk of disease and death (nature and nurture). In essence, the microbiome represents some environmental aspects of disease that you can’t tell from human genetic studies alone.
It also helps explain why the billion-dollar, big-science boondoggle to sequence the entire human genome—known as the Human Genome Project—has been such a spectacular failure. Twenty years later, practicing doctors say they have yet to find this project useful in actually caring for patients, or for so-called “gene therapy” for diseases.
So, perhaps microbiome sequencing will turn out to be more helpful in identifying and curing chronic disease—and extending our lives. Which leads me to the next new study…
The “bad” gut bacteria that shortens your life
Researchers analyzed data from a 47-year study of more than 7,000 Finns.2 They specifically looked for links between mortality and the different kinds of bacteria in the study participants’ GI microbiomes.
The researchers discovered that a type of bacteria called Enterobacteriaceae is a good predictor of mortality. In fact, they found that people who have an abundance of Enterobacteriaceae in their guts are 15 percent more likely to die within 15 years.
The most common Enterobacteriaceae are E. coli—the nasty microbes behind disease outbreaks from contaminated lettuce and other produce. This type of bacteria is also linked to urinary tract and bloodstream infections (like sepsis).
In a healthy GI microbiome, “good” probiotic bacteria crowd out “bad” bacteria like Enterobacteriaceae. And there have been some studies looking at whether taking oral probiotic supplements can prevent “bad” bacteria colonization in the microbiome. Not surprisingly, these studies haven’t reported much success.
That’s because, as I’ve often reported, probiotic dietary supplements simply don’t work. (Most of them can’t survive the assault from stomach acids long enough to do any good in your microbiome.)
The best foods for your microbiome
So, rather than taking useless probiotic supplements, the best way to maintain a healthy microbiome is to eat a healthy, balanced diet that contains plenty of prebiotic foods that supply nourishment for beneficial probiotic bacteria.
Top prebiotic foods include:
- Whole grains
You can also eat fermented foods, which contain natural probiotics. These foods include:
- Pickled vegetables
Many of these prebiotic and probiotic foods are staples in the Mediterranean diet, which, as I often report, can slash your risk of chronic disease. And a new study reveals yet another way it accomplishes this—by keeping your GI microbiome healthy…
The simple diet that helps you live longer
Researchers analyzed the diets of 612 people, ages 65 to 79, in five European countries.3 About half the participants ate their usual diet, and the other half ate a Mediterranean diet rich in fruits, vegetables, fish, legumes, nuts, and olive oil.
After 12 months, the Mediterranean diet group had increased probiotic diversity—including the types of bacteria that have been linked to good health in other studies. This group also had better memory, hand-grip strength, and walking speed (which is the single most important indicator of longevity) than the other group.
In addition, the Mediterranean diet group had fewer GI bacteria that are associated with chronic inflammation, increased risk of cell damage, colon cancer, fatty liver, and insulin resistance.
The researchers concluded that the Mediterranean diet increases prebiotic and probiotic-friendly nutrients like dietary fiber, vitamins B6, B9, and C, and the minerals copper, manganese, magnesium, and potassium.
A different twist on gut feelings
The final new study I’d like to share with you shows just how intertwined the GI microbiome is with both our physical and emotional health.
Researchers at Oxford University in England examined the relationship between people’s personalities and the composition and diversity of their GI microbiomes.4
The researchers looked at fecal samples from 655 men and women with an average age of 42, from 20 different countries on four continents. They also collected information on 44 other factors relating to behavior, diet, health, lifestyle, and socio-economic measures.
After analyzing all of this information, the researchers found that people who were more sociable had more diverse, healthy microbiomes. But those who were stressed or anxious had less diversity.
They also found that the study participants on dairy-free diets had a less healthy microbiome, which makes sense because full-fat cheese and yogurt contain natural probiotics, as abundantly found in the Mediterranean diet (for more on the health benefits of dairy, see page 7). People who traveled more and ate a variety of foods also had healthier microbiomes.
The researchers broadly linked differences in healthy probiotics to people’s personality traits.
They theorized that declines in microbiome diversity (primarily driven by poor, restricted diets) may relate to declines in psychological health in modern society.
Bottom line? To stay healthy in body, mind, and soul, listen to your gut. Because nourishing your microbiome with a healthy, balanced diet—like the Mediterranean diet—is a key factor for living a longer, happier life.
3“Mediterranean diet intervention alters the gut microbiome in older people reducing frailty and improving health status: the NU-AGE 1-year dietary intervention across five European countries.” Gut 17 February 2020.
4“Gut microbiome composition and diversity are related to human personality traits.” Human Microbiome Journal, Volume 15, March 2020, 100069.