It used to be that people thought gut health was just about how well you digested what you ate, but researchers are starting to tie it to immune function, emotional regulation, brain health, performance, recovery, and more. In this post, we'll explore some of the ways gut health impacts overall wellbeing and suggest a few simple steps to improve it through nutrition, exercise, and hydration. 

To say there’s a lot going on in your gut is an understatement. It’s the largest component of the human microbiome, which is a collective term for bacteria, fungi, viruses, and other tiny organisms. According to researchers from Emory University, “There are 10x the number of microbial cells in the human gut than in the whole human body, totaling roughly 100 trillion microbes, representing as many as 5,000 different species, and weighing approximately 2 kilograms.” There are also 100 billion nerve cells that line the gut, meaning that much like your hands, feet, or face, it also has sensory perception to what’s going on around and inside it. Let’s look at how your vast and highly active gut microbiome impacts two key areas of wellbeing.

Minding Your Mental Health and Cognition

The neurotransmitters that regulate your mood and emotional wellbeing are often described as “brain chemicals,” but recently, something called the gut-brain axis has been uncovered. According to a Psychology Today post, 90 percent of serotonin is produced in the gut, rather than in the brain. The author went on to state that “Scientists have found that gut bacteria produce many other neurotransmitters such as dopamine, norepinephrine, acetylcholine, and GABA, which are critical for mood, anxiety, concentration, reward, and motivation.”

Millions of nerves connect the two, and so messages sent from the gut can impact how your mind functions. A 2024 review on mental function in older people revealed that higher levels of the bacteria Verrucomicrobia was associated with improved cognitive flexibility and verbal and working memory. More Gemellaceae was linked with improved attention and recall, while greater levels of Bacteroidaceae correlated with improved concentration, longer attentiveness, and increased memory speed. On the flipside, people with Alzheimer's, Parkinson’s, and dementia were found to have lower levels of multiple kinds of gut flora.

Improving Immune Function

During the first few years of life, the microbiome in your gut helps your immune system develop, and when you become an adult, it continues to maintain it. In fact, up to 70 percent of immune cells are found in your intestines. A review published in Gut Microbes found that gut bacteria help modulate four different types of T cells, the All-Stars of the adaptive immune system, that help your body figure out how to respond to a threat. These lead to production of cytokines that protect against intracellular microbes, attack parasites, limit and control infections, and regulate response to viruses.

Gut organisms also play a role in releasing B cells. These produce antibodies that combat disease, pathogens, and toxins. The gut microbiome prompts development of antigen-presenting cells (APCs) that the authors wrote, “protect the body against infection while still maintaining immune tolerance to the normal gut microbiota.” A kind of white blood cell called neutrophils are produced in the gut too. These neutralize invading microorganisms at the site of infection by ingesting them and release enzymes that neutralize microbes. The gut is also home to natural killer cells, the elite fighting force of the immune system, which identify and eliminate cells infected with cancer and viruses.

Now that we’ve seen how a diverse microbiome can improve immunity, mental health, and cognitive function, let’s explore a few simple ways to enhance your gut health.

Pumping Up Prebiotics

Probiotics get all the good press, and some people view them as a cure-all. But while they are useful, there’s another food group that can be just as beneficial. In her book Gut, Giulia Enders explained that “Prebiotics are much more suitable for daily use than probiotics. This is exactly how prebiotics can help: they are roughage that can only be eaten by nice bacteria. Bad bacteria cannot process prebiotics at all, or hardly, and so they cannot use prebiotics to produce their evil chemicals. At the same time, good bacteria fed with prebiotics grow constantly in power and can gain the upper hand in the gut.”

These good bacteria she’s talking about like to feast on foods that are rich in fiber that the body can’t fully digest. Some of what’s left acts as fuel for probiotics and other beneficial organisms. Some of these turn prebiotics into short chain fatty acids, which a 2021 study published in Molecules states can regulate cardiovascular, metabolic, and inflammatory biomarkers, improve the absorption of calcium and other minerals, control blood sugar, reduce body weight, and boost immunity.

Some widely available fiber-rich foods include asparagus, endive, artichokes, garlic, and onions. Another type of gut-healthy prebiotics is resistant starches. The resistant bit of their name indicates that they’re not fully digestible and so like fiber-rich prebiotics, they act as kindling for beneficial bacteria. Examples include regular and sweet potatoes, plantains, green bananas, beans, peas, lentils, oats, and barley. If cooked, most of these need to be left to cool, as temperature impacts their absorption.

Pursuing Probiotic Foods

According to ScienceDirect, “Probiotics are living microorganisms that confer a health benefit to the host when administered in adequate amounts.” The main advantage is increasing the number of “good” bacteria in the gut. Probiotic supplements can be valuable and provide high doses of certain strains, but it’s also possible to get most of what you need from your diet.

 Per a 2022 review, “several studies have shown that fermented dairy probiotics products improve human health by stimulating the growth of good bacteria in the gut at the same time increasing the production of metabolic byproducts.” The authors noted improvements in immune function, including increased production of all the cell types mentioned earlier. These are possibly due to the probiotic strains Lactobacillus, Streptococcus, Lactococcus, Bifidobacterium, and Leuconostoc found in Greek and Bulgarian yogurt, kefir, and fermented cottage cheese.

A research team from the University of Minnesota discovered that kimchi, sauerkraut, and pickles also have a beneficial impact on gut health. “Lacto-fermented vegetables have a significantly greater effect on some of the functions performed by microorganisms in the gut and on the nutrients that our microbiome uses to perform functions with potentially key effects on health,” they concluded.

Working Out Your Bacteria               

It’s a common assumption that the only gut-related benefits of exercising are getting rid of belly fat or developing beach-ready six pack abs. But there are actually some internal changes that can occur too. Finnish professors asked 18 sedentary people who were prediabetic or had type 2 diabetes to perform either intervals or moderate speed cycling for 40 to 60 minutes three times a week. After just six sessions, both groups had more Bacteroidetes bacteria. This improved the breakdown of carbs and protein and releases anti-inflammatory molecules in the gut. The workouts also reduced the level of two other types of bacteria that can negatively affect immunity.

Another trial by Jeffrey Woods and his colleagues at the University of Illinois Urbana-Champaign asked people to run on a treadmill or ride an exercise bike for 30 to 60 minutes three times a week. Six weeks later, they had increased levels of Faecalibacterium and other bacteria that produce butyrate, which regulates gut barrier function, fuels cells, and reduces inflammation.