A Surprisingly Simple Hack for a Healthy Gut

An easy dietary practice works to block pathogens and keep your gut microbes happy.

“It is time for parents to teach young people early on that in diversity there is beauty and there is strength.” –Maya Angelou

We have a couple of pounds of bacteria living in our intestines called the gut microbiota. It acts like a bona fide organ and a multi-talented one at that. It has immune, digestive, neural, and hormonal functions. This is a story about immune function. Before our immune system is even aware of pathogens, our gut microbes may have already killed them off. That’s a pretty good showing for a part of our body that isn’t even human.

A poorly balanced microbiota can let microbes seep into the bloodstream, where they can cause inflammation. That can affect all parts of our body, including our brain. We now know that the brain responds to this onslaught with anxiety and depression. That is the surprising premise of the gut-brain connection, and it is changing the face of psychiatry.

We have long known that a diverse microbiota, bustling with thousands of different species of bacteria, fungi, and viruses, is healthier than one with a few dominant species. But why? New research from Frances Spragge, Erik Bakkeren, and Kevin Foster at Oxford, outlines how a healthy microbiota fights pathogens: It starves them. They call the phenomenon nutrient blocking. The researchers add, “Understanding how nutrient blocking works is powerful because it allows us to predict which gut communities will be protective against a given pathogen.”

They were particularly interested in how the microbiota could fight off two specific pathogens, Klebsiella pneumoniae and Salmonella enterica, because those are becoming resistant to antibiotics. They found that they could predict which groupings of microbes could block a given pathogen, based on its dining proclivities. This could lead to new therapies for Crohn’s, IBD, IBS, and other inflammatory diseases.

How it works

A healthy person has a microbiome that has lived with them since they were babies. The individual microbes have a high turnover, which allows the microbiota to respond quickly to changes in diet, but it still maintains a stable core that represents our distinct microbiome.

That unique collection of microbes came together when we were weaned and first started eating bacteria-laden food. In our world, bacteria are unavoidable. We can wash our veggies all we want; bacteria also live inside our food.

Different microbes eat different substances, and one microbe’s secretions are another one’s food. After a while, a compatible group of microbes learn to balance each other out. Once established, a microbiota can be hard to change. (Not impossible, though. Antibiotics, smoking, cancer drugs, and drinking can all change your gut microbiota.)

A mature microbiota is ruthlessly efficient. As soon as you eat a candy bar, for instance, certain sugar-loving microbes like Proteobacteria will bloom, rapidly consuming the sweets and sending you a little jolt of feel-good dopamine as a thank-you. After every molecule of sugar gets sucked up, the sugar-lovers die down to a standby level, ready to rally with the next candy bar.

When a pathogen has the temerity to drop in on our microbiome, there is nothing for them to eat. The efficiency of our microbiota means pathogens that arrive late to the party simply starve. The more diverse our microbiota, the more different foods are monopolized and the less likely that a pathogen will find anything to eat. This is a terrific reason to support a diverse microbiota.

More than just diversity

Some microbes seem to be more combative. They eat the same diet as a pathogen, and in many cases, they are related.

E. coli is a well-known pathogen, except that some strains are model citizens in our gut and will outcompete the bad strains. There is no familial love between microbes. In general, related species fight it out the hardest because they compete for similar resources. The one that best fits the environment will come out on top, and all its cousins are generally banished.

On their own, these microbes are insufficient to fight off a pathogen. But with the backing of a diverse collection of microbes, these select microbes can ensure victory over a pathogen invasion.

How to build a better microbiota

This research may someday offer us simple ways to get a robust microbiome, tuned to fight specific pathogens. Until then, there is something simple we can do to fine-tune our microbiota: Expand our dietary choices.

To get more diversity in your gut, eat a more diverse diet. A perfect example is the Mediterranean diet, which includes small portions of highly varied foods. Contrast that to the Standard American Diet (SAD) consisting of a limited palette of corn byproducts, hamburgers, and Snickers.

In particular, you should eat plenty of high-fiber veggies and fruit, like onions, beans, asparagus, artichokes, and berries. Fiber gets converted by bacteria into short-chain fatty acids which nurture and nourish the cells lining your gut. And, as mentioned, contented microbes can even produce neurotransmitters like dopamine and serotonin, helping to optimize your mood and cognition.

For top gut health, it takes a village, and the more diverse, the better.

References

Spragge, Frances, Erik Bakkeren, Martin T. Jahn, Elizete B. N. Araujo, Claire F. Pearson, Xuedan Wang, Louise Pankhurst, Olivier Cunrath, and Kevin R. Foster. “Microbiome Diversity Protects against Pathogens by Nutrient Blocking.” Science 382, no. 6676 (December 15, 2023): eadj3502.