First, the gut or gastrointestinal system covers a lot of ground within the body and includes the following body parts:
- The mouth.
- Salivary glands.
- Small intestine.
- Large intestine.
“The concept of gut health stems from the function of the gastrointestinal tract particularly the esophagus, stomach and intestines working in synergy with the liver, pancreas and gallbladder to help the body digest and absorb dietary nutrients,” says Kalee Eichelberger, a registered dietitian with Orlando Health Orlando Regional Medical Center in Florida.
When we’re talking about good gut health, we’re referencing “how effectively the body is able to carry out this digestive function without complication, such as causing symptoms of discomfort, bloating or upset stomach, which can occur in the setting of digestive disease,” she explains.
In addition to how well your gut carries out the various aspects of digestive function, the concept of gut health also includes the makeup of the trillions of microorganisms that make their home in your gut. You’ll likely hear the term gut microbiome, which refers to the beneficial microorganisms that help your body with many different functions including:
- Digesting and absorbing nutrients.
- Supporting the immune system.
- Protecting the body from ingested pathogens.
- Synthesizing vitamins, or creating certain needed vitamins from foods as the bacteria in the gut act on those items.
- Excreting waste products.
Cesar Sauza, clinical nutrition manager, health education and wellness, at AltaMed Health Services in Los Angeles says “a healthy gut is one that has both a rich and diverse gut microbiome.”
Why Gut Health Is in the News
You’re hearing more about gut health and the gut microbiome lately because “the medical community is becoming increasingly aware of the impact of the gut microbiome on multiple organs and processes that were previously considered to be minimally related to the gastrointestinal tract,” says Dr. Robert Lerrigo, associate chief of gastroenterology at Santa Clara Valley Medical Center in California.
The gut microbiome and its variations have been implicated in several diseases and conditions including:
- Inflammatory bowel disease. IBD is an umbrella term that includes Crohn’s disease and ulcerative colitis. Crohn’s and ulcerative colitis both involve inflammation in the digestive tract and can cause similar symptoms including abdominal pain, gas, bloating and constipation or diarrhea.
- Small intestinal bacterial overgrowth. Also called SIBO, this serious condition develops when bacteria that should be found only in other parts of the digestive tract begin growing in the small intestine. It causes pain and diarrhea and can lead to malnutrition because the bacteria consume the nutrients from food before the body has a chance to absorb them properly.
- Obesity. Evidence has been building that disruptions to the gut microbiome could be implicated in the development of obesity in some people.
- Insulin sensitivity and other endocrine disorders. Changes to the gut microbiome may alter your body’s ability to use and respond to insulin or other hormones.
- Mental health. Science is finding increasingly that there’s a connection between the gut and the brain. Some studies have found that an imbalance in the gut microbiome could be related to anxiety, depression and dementia, including Alzheimer’s disease.
- Asthma. Good gut health is connected with the body’s immune system, and some research is indicating there’s a link between the gut microbiome and the development of asthma and other lung issues.
- Various cancers. Again, the gut’s influence on the immune system could be related to the development of certain cancers, including colorectal cancer and breast cancer.
Maintaining Good Gut Health
If you don’t have a gastrointestinal disease but just want to help support good gut health, Lerrigo recommends “a diverse diet high in fiber, rich in plant-based foods and low in processed foods.” The Mediterranean diet is commonly recommended as helping support good overall health, including heart, brain and gut health.
If you have a specific need related to gut health, such as trying to control IBD, lose weight or avoid bloating, Lerrigo says you should be sure to discuss these goals with your physician “because the answers can be quite different,” depending on your needs. “It’s also important to realize that what works for others with the same concern may not work for you. Diet plans can be highly individualized.”
And, he notes that “gut health is more than just the foods we consume – it’s how these foods interact with our native gut microbiome and vice versa.” So, it’s important to think about your health holistically and get tailored advice.
That said, in general, increasing intake of dietary fiber and limiting your intake of processed foods can help support good gut health.
Fiber or roughage is an indigestible part of plants. Consuming foods high in fiber can help clean the gut and move waste products out. As such, Eichelberger notes that “increasing dietary fiber can help promote regularity and prevent constipation.”
High fiber foods include:
- Whole grains, including barley, bran, quinoa, oatmeal, brown rice.
- Legumes, including peas, beans and lentils.
- Nuts and seeds.
Types of Fiber
Not all types of fiber are the same. There are two primary types of fiber:
- Soluble fiber. Soluble fiber dissolves in water, and in the gut, it forms a jelly-like substance. It’s a good fiber, because it can smooth out spikes in blood sugar and may help you feel fuller longer. Examples include psyllium (the kind of fiber found in the powder fiber supplement products you can blend with water or juice), pectin and gums.
- Insoluble fiber. Insoluble fiber, on the other hand, doesn’t dissolve in water and passes through the GI tract largely intact. Sometimes called a bulking agent, it can help move food and waste through the gut. Examples of insoluble fibers are cellulose and lignin.
Within these two main types of fiber, the following subtypes have been associated with health benefits and are thought to support good gut health for most people. You should seek to include these fibers in your diet:
Fermentable fiber: Good bacteria in the gut use this type of soluble fiber as energy. Inulin, pectin and guar gum are examples, and legumes are good sources.
Viscous fiber: Also a soluble fiber, viscous fiber makes a very thick, gel-like substance when blended with water. This type of fiber sits in the gut and slows down digestion and absorption of nutrients. It’s responsible for making you feel fuller longer, and as such has been associated with weight loss. Pectin, glucomannan (which is sometimes marketed as a weight-loss supplement) and psyllium are examples.
A very viscous type of of fiber called beta-glucan has been shown to improve insulin sensitivity and lower blood sugar levels. These fibers are found in legumes, asparagus, oats, flax seeds and Brussels sprouts. Viscous fibers have also been associated with reducing cholesterol levels, which may improve heart health and help you feel fuller longer.
Resistant starches: Starches are strings of carbohydrates found in potatoes, grains and other high-carb foods. Some of them resist digestion and pass through the GI tract largely unchanged. A type of soluble fiber, resistant starches have been associated with enhanced insulin sensitivity, lower blood sugar levels and reduced appetite. Legumes, corn, beans and raw oats are all good sources of resistant starches.
Fructans: Oligofructose (or fructooligosaccharides) and inulin are fructans (a type of fructose molecule) that good gut bacteria can use as fuel. Because of their structure, they remain largely undigested until they reach the large intestine – where most beneficial gut bacteria are concentrated. For some people they can quell diarrhea, but in others, they can cause gastrointestinal distress. They are found in chicory root, Jerusalem artichokes and shallots – though wheat is the primary source of fructans for most people.
Improving Gut Health
If your diet is currently low in fiber, Eichelberger recommends “gradually increasing dietary fiber to help prevent symptoms such as gas and bloating. The Academy of Nutrition and Dietetics recommends that women aim for 25 grams of fiber per day, while men should aim for 38 grams per day.”
Increase dietary fiber by eating more fruits, vegetables, whole grains, nuts and seeds. However, if you have IBS or another digestive disease, you may be told to reduce the amount of fiber you’re consuming to reduce symptoms, so talk with your doctor or a registered dietitian.
Boosting the amount of whole foods you eat should go hand-in-hand with reducing the number of processed foods you consume. Eichelberger notes that “recent research suggests that limiting processed food items might help reduce inflammation that could be related to specific food additives,” such as emulsifiers and bulking agents, which are thought to disrupt the normal function of the GI tract. Some research has also suggested that these additives could increase anxiety or exacerbate other mental health issues.
Other recommendations for improved gut health include:
- Eating slower and chewing thoroughly. Slowing down how quickly you eat and chewing each bite completely can help promote healthy digestion. Chewing is the first step in digestion, so slow down, savor your food and take some of the burden off the internal organs by letting your teeth and tongue play their part.
- Eating smaller meals. “Try to follow your hunger cues and eat smaller, more frequent meals thought the day,” Eichelberger says. Smaller, more frequent meals may be easier to digest than larger volumes of food.
- Setting a gut bedtime. Eichelberger says you should “limit your late-night snacking,” as the GI tract is more active during the day. Giving your GI tract a rest in the evening can help it function more optimally when it’s active.
- Managing stress.Relaxation techniques such as yoga and meditation can help you control stress and help keep your GI tract in balance. “New studies are showing a gut-brain connection with mental health impacting GI symptoms,” Eichelberger says.
- Exercising more. Exercise gets the blood moving and can stimulate the GI tract to do what it needs to do. Exercising regularly is a great way to support good gut and overall health and wellness.
Probiotics and Prebiotics
Any discussion of gut health also needs to include probiotics and prebiotics.
- Probiotics: Probiotics are the so-called “good” bacteria and other microorganisms that reside in the gut and are believed to support a healthy immune system and good digestion.
- Prebiotics: The term prebiotics refers to the dietary fibers that these good bacteria feed on.
Both can be found in foods and supplements. Fermented foods are good sources of probiotics. Examples include:
- Pickles (salt-based, not vinegar-based, which are not fermented).
- Some cheeses, such as Gouda, cheddar, Parmesan and Swiss.
- Sourdough bread.
Prebiotics can be found in many high-fiber foods, such as vegetables, fruits, whole grains, beans, legumes, nuts and seeds. Especially rich sources of prebiotics include:
- Chicory root.
In addition, many companies offer probiotic and prebiotic supplements that are supposed to help these beneficial bacteria thrive.
“There is some research that suggests probiotics may help manage antibiotic-induced diarrhea or help manage IBS symptoms,” Eichelberger notes. “Probiotics are available both as over-the-counter dietary supplements or can be can found in certain fortified foods such as yogurt, kefir and other fermented food items,” including kimchi, kombucha and sauerkraut.
Sauza adds that “it’s best to work on dietary changes first before resorting to supplementing. However, there could be benefits in supplementation. A daily probiotic supplement will give a boost to the gut microbiome, this could be even more beneficial for those with digestive and GI-related issues or following an antibiotic treatment to help replenish healthy bacteria.”
If you’re going to add a probiotic, he recommends looking for “a supplement with various species of Lactobacillus and Bifidobacterium,” bacteria. Aim for “10 billion CFUs or greater for adults and 4 to 6 billion CFUs for children.”
Both Sauza and Eichelberger stress that you should check with your doctor first before adding a supplement.
A Word of Caution
Lastly, Lerrigo notes that gut health can mean different things to different people, and there’s a lot of interest right now in the role the gut microbiome plays in overall health and wellness, particularly in terms of addressing common ailments such as:
- Insomnia and sleeplessness.
- Autoimmune disorders.
- Constipation or diarrhea.
“Gut health has almost a spiritual meaning to some who take to heart that mantra we’ve all heard before, ‘you are what you eat,’” he says.
Some of these claims of how gut health can improve overall health and well-being may not be fully grounded in science just yet. While there’s a lot of exciting stuff happening with regard to our understanding of gut health and its overall importance, Lerrigo recommends proceeding with caution.
“Before you rush to get your gut microbiome sequenced or start a Candida cleanse diet or get a mail order fecal transplant (which is exactly what it sounds like and is being studied as a potential treatment for a range of disorders and diseases), it’s important to take a step back and realize that this is all very, very new territory for scientists,” he stresses. “There are some cases where the commercialization of the gut microbiome has grown beyond what’s supported by the actual science.”
He also notes that an article published in the British Medical Journal in 2018 showed that 80% of all research articles related to the gut microbiome published over the last 40 years were released between 2013 and 2017. “We’ve come a long way in understanding the importance of the gut microbiome, however, we’re still in the early stages of translating this into therapies that actually help cure, control or prevent diseases,” Lerrigo says.