Gut Health: The Basics

 

“Gut health” is a popular term, but what does it really mean? Learn the basics about the gut and how to keep yours in good working condition. 

What Does the Gut Actually Do? 

The “gut” refers to the small and large intestines. The small intestine is the site of nearly all food breakdown and nutrient absorption. In contrast, the large intestine (called the colon) is largely responsible for processing indigestible food material (mostly fiber) to feed the microbes that live there. More on that in a moment.

The digestive system has its own nervous system called the enteric nervous system (ENS). With an estimated 100 million or so nerve cells lining the gastrointestinal tract, the ENS oversees and coordinates digestion without the help of the central nervous system (CNS) – the one that involves your brain. However, experts say the ENS and the CNS do communicate with each other. For example, in people with irritable bowel syndrome, constipation, diarrhea, and bloating, the ENS may trigger emotional shifts that occur in the brain. 

The gut is also home to 70% to 80% of immune cells. The intestinal lining helps to prevent toxins present in the intestine from entering the bloodstream where they could cause trouble. 

Home to Bacterial Bodyguards

The gut is populated with a collection of hundreds of different types of microorganisms invisible to the naked eye.  The colon contains the most microbes, which number about 100 billion. Most of those microbes are bacteria. 

The majority of gut bacteria are good citizens, although some of them are sketchy. Troublesome bacteria lurk in the gut along with viruses, fungi, and other tiny invaders that can make you sick.  However, beneficial bacteria outnumber pathogens in healthy people, and that keeps the gut environment in balance most of the time. 

You may be wondering why you need gut microbes. Beneficial gut bacteria are essential. While gut microbes aren’t a part of you like your brain, heart, or kidneys, life would be impossible without them. You need gut microbes to regulate bodily functions as much as they need you for water, warmth, and food. 

Gut microbes produce compounds such as vitamin K and several B vitamins (neurotransmitters to help nerve cells communicate with each other) and short-chain fatty acids (SCFA), which are the workhorses of the gut. SCFA provides energy for the gut and the rest of the body, inhibits the growth of pathogens, helps reduce inflammation in the gut, boosts the body’s absorption of calcium and magnesium from the colon, and much more. Short-chain fatty acids are key to overall well-being, and gut microbes make SCFA possible. 

Your Gut Is Special 

As an adult, the microbial community in your gut is the sum of your exposure to microbes, your lifestyle habits, and more.  Before birth, the gut is basically a blank slate. Very soon after you enter the world, microscopic settlers from your mother and the environment start moving in. You accumulate more and more microbes until about age 3. when the gut becomes relatively stable and is considered adult-like. 

The original microbial settlers reflect your genetics, how you were born, what you ate early in life, where you lived, and whether you had a pet, among other factors. During adulthood, eating habits, infections, health conditions, and medication use can change the gut for better or worse. 

While humans have many types, or species, of microbes in common, the gut microbiome is as unique as a fingerprint. Nobody knows what constitutes the “perfect gut,” but experts are sure that a diversity of beneficial gut bacteria matters most to good health. Diet is one way to influence gut microbe diversity. 

The Care and Feeding of Your Gut 

We can’t digest fiber, but our colonic gut microbes are capable of fermenting it.  Foods rich in fiber, such as whole grains, beans (legumes), fruits, vegetables, nuts, and seeds promote SCFA by nourishing the beneficial bacteria that produce them. The Dietary Guidelines for Americans suggest eating at least 28 grams of fiber every day on a 2,000-calorie eating plan for healthy people. Yet more than 97% of American adults don’t get enough fiber.  Low-fiber diets can encourage the growth of pathogens by changing the environment of the gut and allowing the bad guys to thrive. Fiber is also necessary to prevent constipation. 

A balanced eating plan with a variety of at least five servings (combined) of fruits and vegetables and a minimum of three servings daily of whole grains, such as oatmeal, whole wheat bread, and popcorn, is an easy way to meet quotas without counting grams of fiber. A diet rich in a variety of plant foods supports a greater diversity of gut microbes. Foods with live active cultures, including yogurt, kefir, and some kimchi and sauerkraut, provide beneficial bacteria. But they must be consumed regularly to make a difference. Try to include one serving a day of probiotic foods. 

If you don’t have gastrointestinal problems, following a balanced, plant-rich eating plan with some probiotic foods is the best strategy for a healthy gut. Smoking and stress also affect gut health.