- Gut health is a buzzy topic and products claiming to support it are everywhere.
- Scientists are working to uncover all the ways the gut microbiome is linked to overall health.
- Research has linked a healthy gut to better mental health, digestion, and hormonal balance.
Gut health is in vogue right now, and plenty of research suggests it's a trend worth buying into.
Many prestigious universities, including Oxford, Stanford, UCLA, and King's College London, have labs dedicated to studying the gut microbiome, the trillions of microbes that live in our digestive lining.
From balancing hormones to reducing our risk of developing certain diseases, research suggests these microscopic creatures are crucial to many bodily processes. Some experts even call the gut the second brain.
"Gut health influences overall health, so it's vital to ensure your gut microbiome is healthy," professor Tim Spector, nutrition scientist and co-founder of the science and nutrition company ZOE, told Business Insider.
People with an unhealthy gut microbiome might experience symptoms such as diarrhea, constipation, bloating, and excess wind, he said.
A gut lacking in a diverse range of microbes can also affect the immune system, and increase the risk of inflammatory diseases, weight gain or obesity, depression, anxiety, nutrient deficiencies, skin conditions, and allergies, Dr. Arpana Church, a psychologist and co-director of the Goodman-Luskin Microbiome Center at UCLA, told BI.
Because of this wide-reaching impact, commercial companies are racing to roll out products claiming to boost our gut health, from yogurt to "gut-friendly" soda. The gut health supplements market, meanwhile, is valued at $12 billion.
Experts have told BI, however, that the best way to nurture our gut health is to eat a diverse range of fiber-packed healthy foods.
Below, top gut health researchers break down the ways that our gut affects our health.
Digestion
Unsurprisingly, a healthy gut helps our bodies to smoothly digest food and absorb nutrients, Church said.
As well as being able to digest food, a healthy gut has regular bowel movements and doesn't cause issues day to day, Gabrielle Morse, a gut health specialist and registered dietitian at The Gut Health Clinic, previously told BI.
Experts believe a diverse gut microbiome helps with this. "They look after us when they're in a favorable swing," Morse said.
Research suggests that eating a wide range of plant foods, such as fruits, vegetables, whole grains, legumes, nuts, and seeds, supports a diverse gut microbiome. These foods all contain fiber, which feeds the "good" bacteria in the gut.
The immune system
Around 80% of the body's immune cells are found just outside the gut lining, Spector said. So your gut bacteria and the chemicals they produce regularly interact with the immune system.
This interaction helps "train" the immune system to know when to respond to a threat and when everything is OK, he said.
People with a healthy microbiome have a thicker protective layer that stops waste products and microbes from crossing over the gut lining into the immune tissues, which reduces the likelihood of inflammation, one of the body's natural defenses against infection, Spector said.
Acute inflammation — the redness, warmth, swelling, and pain we feel around an injury — is healthy. But when inflammation lingers on for too long it becomes chronic, which can lead to white blood cells attacking healthy tissues, according to Harvard Medical School.
Chronic inflammation has been linked to various diseases, such as heart disease, diabetes, cancer, arthritis, Crohn's disease, and ulcerative colitis.
Mental health
There's strong evidence that a good diet is linked to better mental health, brain health, and mood, likely because it promotes a healthy gut microbiome, Spector said.
The gut and the brain are in constant communication with each other via multiple pathways, such as the vagus nerve, Church said. This bidirectional connection is known as the gut-brain axis.
"Think about that high-pressure situation when you have to go for a job interview or go on a date. We often experience being both lightheaded and having weird sensations in our stomach," she said.
Church likes to describe the gut and the brain as "BFFs" because "they go hand in hand."
Any change to the gut microbiome will disrupt communication with the brain, leading to changes in mood, cognition, and emotional regulation, she said.
The easiest way to support the gut-brain connection is by eating a diet rich in fiber, omega-3 fatty acids, and antioxidants, and cutting back on processed foods, added sugars, artificial sweeteners, and alcohol, she said.
Numerous studies suggest that people with depression and anxiety often have different gut microbes to those who don't. For instance, a depressed person might have lower levels of certain beneficial bacteria and higher levels of potentially harmful bacteria.
Hormonal health
Hormones are substances produced by glands that act as messengers, letting the body know when it's time to do certain jobs.
Gut bacteria play a crucial role in maintaining a healthy hormonal balance in the body, Dr. Max Nieuwdorp, an endocrinologist who researches the role of the gut microbiome in hormonal processes, previously told BI.
They are involved in the release and production of dozens of different hormones and can influence the brain via the central nervous system, according to his book, "The Power of Hormones."
For instance, producing serotonin and dopamine, which are essential for regulating mood and anxiety, Church said.
The benefits of gut health likely stretch even further
There's lots of emerging research that suggests the reach of the gut microbiome extends even further, too.
Gut health might influence the lungs, kidney, mouth, gums, and skin, as well as bone density and sleep quality, Church said.
Scientists are also investigating the direct links between gut health and a range of diseases, Spector said, including colorectal cancer, cardiovascular disease, and metabolic diseases.