Your gastrointestinal tract – GI or “gut” for short – is a group of organs that start at the mouth and end at the rectum. Its main job is to break down, digest, and absorb food to turn it into the energy and nutrients you need to survive. But the gut is also home to the gut flora or microbiome, a complex world of up to 1,000 bacterial species and other microorganisms that benefit and influence many aspects of human health. Here are five facts you may not know about your gut:

Your gut microbiome is like a unique fingerprint

When researchers began studying bacterial colonies in the gut a few decades ago, a myth that microbial cells outnumber human cells in the body by a 10:1 ratio became quite popular. It probably came from the fact that there are so many bacteria in the GI tract; the human microbiome is estimated to harbor tens of trillions of microorganisms and weigh up to six pounds. But the population of bacteria in the gut is also unique to each individual, and the number of microbial colonies varies widely from person to person.

gut health

A 2015 study from Harvard’s School of Public Health revealed that any given gut microbiome contains enough unique bacterial features to identify and tell individuals apart. The authors of the study analyzed microbiome data from hundreds of participants and created individual “codes” that turned out to be unique among hundreds of individuals. Much like your DNA imprint, this code is one of a kind, and a significant part of it is inherited or transmitted from parent to child during childbirth and lactation.

Your gut has a brain of its own

You may have heard about the “gut-brain connection” or “gut-brain axis,” the impressive network that connects the gut and the brain and allows it to communicate back and forth. But, in contrast to other vital organs like the heart, the gut doesn’t need the brain’s input to do its job – it has a brain of its own.

The enteric nervous system (ENS), sometimes called the “second brain,” is made up of two thin layers of hundreds of millions of neurons that line the GI tract. It operates independently from other organs, and, unlike the brain in your head, the ENS can’t write an email or calculate a restaurant tip. Its main job is to control digestion and regulate gastric functions. However, emerging research shows that while the ENS can’t think for you, it does influence your mood and may even play a role in neurological disorders ranging from anxiety and depression to Parkinson’s and Alzheimer’s disease.

A serotonin factory

Serotonin is a chemical that functions both as a hormone and as a neurotransmitter. It plays a role in several essential functions, including sleep regulation and bone health. But it is perhaps most known for its effects on mood regulation and its connection to depression.

Serotonin is one of several brain chemicals that contribute to an overall sense of well-being. An imbalance in serotonin levels has been shown to impact mood negatively and may lead to depression. However, despite being a “brain chemical,” recent research reveals that up to 95 percent of the body’s serotonin is made in the gut. This means that serotonin’s functions extend beyond the brain and play an essential role in digestion and other gastrointestinal processes.

 

There may be a connection between gut health and ADHD

Given the strong bi-directional relationship between the brain and the gut, many experts believe that the gut microbiome may directly influence certain neurological and neurodevelopmental disorders.

A 2019 literature review found that kids with ADHD have a different gut microbiome composition, compared to healthy children. Their results suggested that bacteria from the genus Bifidobacterium seemed to be one of the strongest predictors for ADHD. On the other hand, another recent study published in Nature’s Scientific Reports found that children with ADHD who supplemented with micronutrients (vitamins and minerals) had a richer microbial diversity and significantly fewer Bifidobacterium in their GI tracts.

 

You can improve your gut microbiome through food

When talking about gut health, the old proverbial saying “you are what you eat” couldn’t be any truer. Proteins, fats, carbs, sugar, and processed foods all trigger changes in the gut microbiome that will eventually impact – positively or negatively – your overall health.

Consuming foods that contain live, beneficial microorganisms, like fermented foods, promotes the growth and development of healthy bacteria in the GI tract. These foods are often called “probiotics” and can help with a wide range of health problems, including digestion issues, allergies, and inflammation. Probiotic foods have also been shown to support heart health, boost the immune system, and may even help you lose weight.

Here are some of the healthiest probiotic foods to add to your diet:

  • Yogurt
  • Buttermilk
  • Pickles
  • Aged cheese
  • Apple cider vinegar
  • Kimchi
  • Kefir
  • Sauerkraut
  • Kombucha