“Our body teaches us that health lies in balance and harmony, rather than in conflict and fighting.” – Ilchi Lee

BY Amelia Buckley

Whether choosing a sandwich option for lunch or accepting a new job offer, we’re all familiar with gut instincts. Although the term “gut instinct” only gained popularity in the 1970s, the concept that emotions are tied to the gut dates back to ancient times. This long-standing idea may have more scientific basis than we realize as more and more research emerges about the extensive impact that gut health has on the rest of our bodies and even our mental health.

What is gut health?

“Gut health” refers to the function and balance of bacteria in the gastrointestinal (GI) tract. Also called the microbiome, this collection of bacteria is unique to each individual and impacts how our body digests food. According to the National Institutes of Health, 70 million Americans suffer from digestive disease or poor gut health. This common issue is caused by a variety of factors including environmental conditions, diet, exercise, sleep, and genetics.

Best foods for gut health

As gut health determines how we digest food, diet is a key factor in promoting a healthy microbiome. Eating a wide variety of whole, unprocessed foods, including lots of fruits and vegetables, is essential for improving gut health.

According to Tim Spector, M.D., professor of genetic epidemiology at King’s College London, making sure you eat 30 different types of plants each week is a great starting point for supporting gut health. Dr. Spector references a 2018 study published by the American Society for Microbiology. The researchers looked at 11,000 people’s gut microbes and their corresponding eating questionnaires and discovered a key component to gut health. “It turned out that people who had the healthiest guts, which is generally the most diverse guts, were the people eating more than 30 different types of plant in a week,” explains Dr. Spector.

While 30 may sound like an overwhelming number of plants to consume within the span of a week, Dr. Spector assures us that it’s not as hard as you may think. “People forget what a plant is. A plant can be a nut, a seed, a grain. It can be an herb, a spice. So, it’s actually not that hard as long as you don’t have the same thing every day. That diversity was much more important than if you were vegan or vegetarian or meat-eater,” he says.

You can help yourself reach the golden number 30 by throwing in a couple of varieties of nut butter to your diet, having whole-grain toast, making sure to include a salad at lunch, and perhaps finish it off with cauliflower pizza for dinner. By the end of the day, you’ll have had almost a dozen different types of vegetables!

Fermented foods that are good for the gut

Eating fermented foods, which are high in probiotics, is another great way to introduce diverse bacteria to your microbiome. Foods like kimchi, kombucha, yogurt, sauerkraut, and tempeh contain lactobacilli, a type of bacteria that can benefit your health, and are some of the best probiotics for gut health. These are just a few of the fermented foods out there. Look for items labeled with “contains live active cultures.”

Consuming prebiotics and probiotics is another way to support gut health. Prebiotics come from carbohydrates, like fiber, which humans cannot digest. These provide a source of food for the bacteria in your gut and can be found in legumes, oats, asparagus, leeks, garlic, and more.

Probiotics are more commonly known and are foods with live bacteria in them. These replenish the healthy bacteria in your gut and can be found in supplement form or in fermented foods. Consult your physician on whether a probiotic supplement would be beneficial for your gut health. 

Signs of poor gut health 

Gut health issues can range from a slight imbalance to significant painful symptoms, but some of the major signs of a microbiome imbalance include bloating, fatigue, stomach pains, migraines, mood issues, food cravings, skin irritation, and unintended weight changes. Unfortunately, for many people who experience gut health issues, addressing them is a tedious trial and error process. Taking steps to improve our diet and gut health is good for everyone, but for individuals with persistent gut health symptoms, consulting a digestive expert can be beneficial in ruling out which food groups are causing the discomfort.

The good news is that all your hard work pays off with significant health boosts. Research has found that strong gut health reduces the risk of metabolic syndrome, a condition that contributes to type 2 diabetes and serious cardiovascular disease.

Lifestyle factors 

In addition to diet, stress and sleep are influential gut health determinants. Smoking can also take a toll on our microbiome. If you’re experiencing gut health issues, experts recommend looking at lifestyle factors as well as dietary changes.

Taking antibiotics can also negatively impact gut health as the medicine which kills off dangerous bacteria also eliminates healthy bacteria. This is why doctors recommend eating plenty of prebiotics and probiotics when taking prescribed antibiotics. This can help restore the healthy bacteria in your gut and avoid other antibiotic-related complications like diarrhea, nausea, and yeast infections.

It all goes back to the gut 

If it sounds like every aspect of your life can affect your gut health, you’re not exactly wrong. Nearly every part of our lives impacts our microbiome in some way. Even where we grew up or how we were born can make a difference. A daycare in Finland found that replacing the traditional playground surface with natural plants and dirt not only impacted children’s microbiome, but their immune health as well.

The daycare replaced their sandy playground surface with lawn and added native forest species like dwarf heather and blueberries. They also added planter boxes and allowed children to tend them. After just one month, children at the daycare had healthier microbiomes and stronger immune systems than their counterparts in other urban daycares.

Specifically, the children had increased T-cells, increased immune-boosting gammaproteobacteria microbes, and a reduction in interleukin-17A, a contributor to immune-transmitted disease.

Environmental scientist Marja Roslund from the University of Helsinki said, “We also found that the intestinal microbiota of children who received greenery was similar to the intestinal microbiota of children visiting the forest every day.”

These results demonstrate that loss of biodiversity in urban areas can contribute to poorer health outcomes, and that easy environmental manipulation can radically change these health dynamics, especially in young children.

Other research has linked gut health back even further—to birth. Although it might sound a little off-putting, babies born via cesarean section who were fed tiny amounts of their mothers’ fecal material in clinical trials developed thriving gut bacteria similar to those delivered vaginally. The babies were given a very small amount in a controlled setting and showed no negative health implications from the procedure.

Babies born vaginally are covered in their mother’s microbes when they pass through the birth canal, but C-section babies do not experience this, leading to the differing levels of bacteria that colonize the guts of these newborns.

In the trial, doctors collected stool and blood samples from 17 mothers who were due to undergo elective C-sections. Soon after birth, the newborns were given a few million cells of the live fecal bacteria in their first milk feed. When comparing samples of treated newborns to vaginally delivered babies, their gut microbes were remarkably similar.

The brain link 

While the digestive benefits of a healthy gut are well established, contemporary research is starting to dive deeper into the relationship between the gut and the brain. New research from the University Hospitals of Geneva has found a significant correlation between reduced microbiome diversity and Alzheimer’s disease.

To determine this connection, the researchers used PET imaging to analyze amyloid plaque buildup and inflammation markers in the blood of 89 patients, some with Alzheimer’s and some without.

They found that certain bacterial products of the intestinal microbiota correlate with the number of amyloid plaques in the brain, meaning that an altered composition of gut bacteria was connected to the amyloid plaques associated with Alzheimer’s. Although this connection is significant, the researchers are still unsure if gut bacteria composition leads to neurological degeneration or vice versa. More research must be done to make a determination of cause and effect.

Another study looking at premature infants found that gut health therapies could prevent some of the brain damage often associated with significantly premature birth. Early gut development, the brain, and the immune system are closely linked in what scientists call the gut-immune-brain axis. In healthy individuals, communication between the brain and the gut is strong, leading to a healthy gut equilibrium and strong immune system, but in infants born prematurely, this connection can be disrupted, leading to potential brain damage. “In fact, we have been able to identify certain patterns in the microbiome and immune response that are clearly linked to the progression and severity of brain injury,” said researcher David Berry.

The study monitored 60 premature infants born before 28 weeks gestation and, by taking EEGs and MRIs, as well as examining gut health through blood and stool samples, scientists were able to determine that premature birth was generally associated with an overgrowth of the bacterium Klebsiella and the associated elevated T-cell levels. These factors appeared to exacerbate brain damage.

Gut bacteria and mental health 

If potentially preventing Alzheimer’s disease wasn’t enough of a gut superpower, emerging research indicates that gut health might also impact our mental health. The enteric nervous system (ENS), also called the “little brain,” refers to two thin layers of more than 100 million nerve cells lining your GI tract. This system regulates digestion and also communicates with the brain about the health of the rest of the body. This connection between the brain and GI tract has long led researchers to connect mental health conditions like anxiety and depression with gut health. According to Jay Pasricha, M.D., “These new findings may explain why a higher-than-normal percentage of people with IBS and functional bowel problems develop depression and anxiety.” This connection is why gastroenterologists may prescribe antidepressants for IBS. This is also why cognitive behavioral therapy has been shown to soothe gut and digestion discomfort.

Interoception 

Although not everyone with poor gut health will experience mental health issues and vice versa, the connection between the gut and the mind can also show up in more subtle ways. A new study by researchers from Anglia Ruskin University demonstrates a link between negative body image and weak brain responses to signals from the gut and heart. The researchers believe that these newly discovered associations could lead to objective diagnostic biomarkers for mental health disorders as well as new treatment methods.

“We experience our body both from the inside and out: we can be aware of how our skin and limbs look, but also of how hungry we feel or how strongly our heart is beating during exercise,” says Jane Aspell, the lead author of the study. “The brain also continuously processes internal signals that we are not conscious of.”

The investigation of how the brain senses internal body states is called interoception and has gained more popularity in the past few decades. In fact, the US National Institutes of Health has provided over $18 million in funding for interoception-focused studies.

Aspell’s study involved 36 healthy adults. It explored the relationship between body image and interoception by administering to the participants a variety of body image assessments, as well as tracking feelings of body shame and worries about weight. Then, the researchers recorded two different electrophysiological measures of interoception. One is called heartbeat evoked potential (HEP) and tracks the brain’s response to a beating heart. The second measure is called gastric-alpha phase-amplitude coupling (PAC) and tracks electrical activity in parts of the gut and brain in order to measure the brain’s responses to signals from the gut.

The researchers reported that individuals with weaker HEP and PAC measures were also more likely to experience negative perceptions of their external bodies.

“We found that when the brain is less responsive to these implicit signals from inside the body, individuals are more likely to hold negative views about their external bodily appearance,” explains Aspell. “It may be that when the brain has a weaker connection to the internal body, the brain puts more emphasis on the external body and so appearance becomes much more important for self-evaluation.”

The research, while fascinating, is still novel, and so scientists can only hypothesize a causal correlation between weak interoception and negative body image. It is also still unclear which comes first—do weak internal signals between the gut, heart, and brain precede negative body image, or is it the other way around? Could we somehow train our bodies to improve interoception sensitivity to help support better mental health?

We’ve all heard that we are what we eat, and when it comes to gut health, factors that influence our GI tract do in fact determine what we are. Gut health impacts our physical health, immune strength, energy levels, and mental health, and the journey to good gut health begins right when we’re born! With so many factors playing into gut health, cultivating a thriving microbiome can feel overwhelming, but the good news is that focusing on key healthy habits can make a world of difference when it comes to gut health. Eating a balanced, varied diet, steering clear of processed foods, getting outside, and reducing stress are strong fundamentals to start with.

If you think you may have poor gut health, or if you’re just curious about your personal microbiome, at-home gut health tests can tell you more about your personal bacteria levels, as well as other useful information like potential parasites, immune markers, food sensitivities, bacteria overgrowth, and calprotectin (an inflammatory marker associated with irritable bowel disease and tumors.) These generally use stool samples over several days to get a full picture of what’s going on in your GI tract. It’s worth noting however that these tests are still in their infancy, so consulting your physician or a gut health expert is probably a better first step if you’re experiencing gut discomfort.

Unfortunately, there is no one-and-done solution to good gut health. Cultivating a healthy microbiome is a lifelong journey, but it’s never too late to start.