What do I need to know about gut health?

Your gut is home to trillions of microbes. To keep it simple, we’ll call them “bugs.” Together they form a mini ecosystem, or community. It’s called the gut microbiome. “They play a key role in the smooth operation of the human body,” says Corina Serer, MD. She’s a gastroenterologist at ProHEALTH, part of Optum, in Seaford, New York.

Most of the bugs in the gut are helpful. The body needs them to digest food and fight off germs, for instance. But there are some harmful ones, too. They can cause inflammation in the gut and digestive issues. They also break down some foods (like red meat) into chemicals that can harm us.

In general, these bugs live together without problems, Dr. Serer explains. But certain things can disrupt the balance of helpful and harmful germs. This may lead to certain health problems.

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No two gut microbiomes are exactly alike. “Every person’s microbiome is unique. We also know that it shifts over time,” says Niren Jasutkar, MD. He’s the assistant director of gastroenterology and hepatology at Riverside Medical Group, part of Optum, in Secaucus, New Jersey.

The makeup of your gut microbiome is influenced by:

• What you eat. Some foods help friendly germs in the gut grow and thrive. Plant foods and healthy animal foods seem to be the best for our guts. These include vegetables, nuts, seeds, fish and eggs.

  Full-fat dairy, sugar, red meat and processed foods seem to have the opposite effect. Eating a lot of these foods helps bad germs grow. That may raise the risk of chronic health problems.¹

• Where you live. Exposure to certain chemicals may harm your microbiome. These include air pollutants, heavy metals and some pesticides. Over time, the changes from these chemicals can affect your health.²

• Your medications. Some drugs can throw the gut out of balance. They can kill good germs. Antibiotics are a common culprit.³ There are other problem medicines:
  • Proton pump inhibitors (taken for severe heartburn)
  • Metformin (for diabetes)
  • Laxatives
  • Some antidepressants⁴

  If you’re having stomach problems or worried about a certain drug, talk with your doctor.

A balanced microbiome keeps your body working as it should, Dr. Serer says. Here are some of the ways gut health supports your health overall.

Digestion

Good gut bugs help your body break down the parts of food your stomach can’t digest. That gives your body more energy, Dr. Jasutkar says. But harmful ones can cause digestive problems. They can cause abdominal pain, bloating, diarrhea and constipation, says Dr. Serer.

Your body’s ability to fight off bad germs

The body needs a healthy gut to fight harmful germs. “Gut bacteria train the body to protect the healthy bacteria and fight off the harmful bacteria,” explains Dr. Jasutkar.

Mental health and mood

Chemical signals can travel from your gut to your brain (and back again). Different germs send different types of messages.⁵ And these messages can impact your mood. High levels of healthy gut germs are tied to more positive emotions.⁶ Unhealthy bugs may make someone prone to depression.⁷

Gut bugs also help make some neurotransmitters. Those are compounds that carry chemical signals to your brain and help with your mood. As much as 95% of our serotonin (the “feel-good” chemical) is made by germs in our gut.⁶

The link between gut health and mental health is complicated. And we’re only beginning to understand it. There’s no foolproof way to care for mood disorders through the gut yet. But it’s a promising area for future mental health care.

Heart health 

Some bugs are tied to lower levels of LDL, or “bad” cholesterol. (Cholesterol is a fat in the blood.) Others are linked to high blood pressure, heart disease and heart attacks or strokes. The gut may produce harmful compounds when it breaks down certain foods. These compounds can raise cholesterol and damage blood vessels.⁸

Weight

Your bugs can have a big influence on your weight. The gut can affect how many calories you burn. It also produces hormones that may influence appetite. Healthy changes to your microbiome may make it easier to lose weight.⁹

How do I know if I have a healthy gut?

The health of your gut can affect your digestion and other parts of the body. If you generally feel good, chances are your gut is in good shape, too.

Signs of gut problems may start with digestive issues. Your microbiome may be out of balance if you often have symptoms of an unhealthy gut. These may include:

• Constipation
• Diarrhea
• Bloating
• Acid reflux or heartburn

Talk with your doctor if you think you have a problem with your gut. You can share your symptoms and find a way to manage the problem.

IBS is a group of gut symptoms that happen together. They include stomach pain, constipation, diarrhea or bloating. IBS is uncomfortable and can affect your quality of life. But it doesn’t damage the gut like the inflammatory diseases below.

IBS may be caused by many factors. Imbalances in the microbiome may play a role, Dr. Serer says. Too few good germs make it easier for bad germs to take over. This can lead to uncomfortable symptoms and raise infection risk.¹⁰

There’s no cure for IBS. Medications and making certain changes in your life can help. Your doctor may suggest:

• Eating more high-fiber foods
• Avoiding gluten (a protein found in wheat, barley and rye)
• Following a special meal plan like a low-FODMAP diet 
• Exercising regularly 
• Managing stress 
• Getting enough sleep¹¹ 

What other diseases affect the gut?

Other conditions may be closely related to the health of your gut. These include:

• Ulcerative colitis (UC). UC is a type of digestive system disease that affects the large intestine and the rectum. It can cause rectal bleeding, pain and stomach cramps.

• Crohn’s disease. Crohn’s is another type of problem with the gut. Unlike UC, Crohn’s can cause problems anywhere in the gut. It can lead to pain, diarrhea, weight loss and feeling very tired. It can also make it hard for your body to get what it needs from the food you eat.

• Celiac disease. Celiac disease is an autoimmune disease caused by eating gluten. When someone with celiac disease eats gluten, the body attacks the small intestine. Then the body can't get what it needs from the food you eat. Gluten is found in foods made with wheat, barley, and rye as well as many processed goods.

• Colorectal cancer. This type of cancer can form in the large intestine or the rectum. It often starts as a growth in the large intestine called a polyp

Making changes to your meals can increase the good germs in your gut, Dr. Serer says. Eating lots of plant foods tend to be good for gut health.¹ Fermented foods and foods that are high in fiber offer the most benefits.

Fermented foods are made with good germs called probiotics. They add more good germs directly to your gut. Eating more fermented foods has been shown to support healthy gut balance.¹² Fermented foods include:

• Apple cider vinegar
• Kefir
• Kimchi, sauerkraut and other fermented vegetables
• Kombucha (no sugar)
• Miso
• Tempeh
• Yogurt

High-fiber foods include fruits, vegetables, beans and whole grains. Many plant fibers contain prebiotics. These feed the good germs in your gut to help them grow. Eating more fiber can improve gut health quickly. Just 25 grams a day can improve microbiome health in two weeks.¹³ Here is an example of what you could eat to get at least 25 grams of fiber:

• 1 cup of oatmeal (4 grams)
• 1 medium banana (3 grams)
• 1 cup cooked, chopped broccoli (5 grams)
• 1 cup pinto beans (14 grams)

There are many types of fiber that can support gut health. One to pay attention to is resistant starches. They help gut bugs produce short-chain fatty acids, or SCFAs. SCFAs help your body fight bad germs, Dr. Serer says. They can also protect your heart. You can find resistant starches in beans, peas, lentils, oats and barley.

If you’re not eating much fiber now, start slow and add a little each day. Too much fiber can cause constipation and stomach cramps. Drinking plenty of fluids will also help prevent constipation.

Foods to limit or stay away from

Some foods can boost the growth of bad gut germs. This can throw your gut out of balance and lead to health problems. Try to limit your intake of:

• Processed or sugary foods¹⁴
• Fried foods¹⁵
• Foods with artificial sweeteners¹⁶
• Alcohol¹⁷
• Red or processed meat¹⁸

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You may have heard that taking probiotics or prebiotics is good for your gut. Supplements may be helpful for some people. But they’re not right for everyone.

• Probiotics are live germs that are good for your gut. They’re found naturally in foods like yogurt or kimchi. There are probiotic supplements, too. You can find probiotic pills, powders, shots or drinks. Some foods also have added probiotics, like juices, cereals, smoothies or milks.

• Prebiotics are fibers that the body can’t digest. They feed good germs in the gut and help them grow. Prebiotics are found in high-fiber foods like vegetables, beans and whole grains. They’re also available in supplement form.

Many probiotic and prebiotic supplements claim to help with certain health problems. In some cases, they may be useful. “Probiotics may help some people who need to take antibiotics for an infection,” says Dr. Jasutkar. Certain probiotics have been linked to better cholesterol levels, too.¹⁹

There are many types of probiotic germs, though. Not all of them will be helpful for all conditions. And many haven’t been well studied. “The research is ongoing. Patients should speak with their doctors before taking a supplement,” Dr. Jasutkar says. Together you can decide whether a supplement will be useful for you.

Many of the habits that support your health overall are also good for your gut. Besides eating healthy, you can:

• Manage your stress. Stress hormones can have a negative effect on the bugs in your gut. Stress can drive you to eat more processed or sugary foods, too. These foods can help bad bacteria thrive.²⁰ If you’re going through a tough time, mental health support resources from Optum can help. 

• Exercise regularly. Studies show that physical activity is linked to a healthier gut microbiome. Being active also lowers inflammation. That’s good for the germs in your gut. Exercise can help keep stress in check, too.²¹

• Look at your medications. We all have to take antibiotics from time to time. But try to limit your use when you can. Antibiotics can kill off good germs in your gut. Don’t take over-the-counter antacids for long periods, too. These may help bad germs grow.⁴

Your microbiome is a complex network with far-reaching effects. You can keep your bugs balanced with good food and healthy habits. And that may help you feel your best overall.

1. Nature Medicine. Microbiome connections with host metabolism and habitual diet from 1,098 deeply phenotyped individuals. Published January 11, 2021. Accessed August 24, 2022.
2. National Institute of Environmental Health Sciences. Microbiome. Last reviewed April 5, 2022. Accessed August 24, 2022.
3. MicrobiologyOpen. Impact of antibiotics on the human microbiome and consequences for host health. Published January 13, 2022. Accessed August 24, 2022.
4. Gut. Interaction between drugs and the gut microbiome. Published May 14, 2020. Accessed August 24, 2022.
5. Integrated Medicine: A Clinician’s Journal. The gut-brain axis: Influence of microbiota on mood and mental health. Published August 2018. Accessed August 24, 2022.
6. Scientific Reports. Emotional well-being and gut microbiome profiles by enterotype. Published November 26, 2020. Accessed August 24, 2022.
7. Cureus. Gut microbiome and depression: How microbes affect the way we think. Published August 23, 2020. Accessed August 24, 2022.
8. Microbiome. Gut Microbiota and cardiovascular disease: Opportunities and challenges. Published March 14, 2020. Accessed August 24, 2022.
9. Preventive Nutrition and Food Science. The influence of the gut microbiome on obesity in adults and the role of probiotics, prebiotics, and synbiotics for weight loss. Published June 30, 2020. Accessed August 24, 2022.
10. National Institute of Diabetes and Digestive and Kidney Diseases. Symptoms & causes of irritable bowel syndrome. Last reviewed November 2017. Last accessed July 20, 2022.
11. National Institute of Diabetes and Digestive and Kidney Diseases. Treatment for irritable bowel syndrome. Last reviewed November 2017. Last accessed July 20, 2022.
12. Cell. Gut-microbiota-targeted diets modulate human immune status. Published July 12, 2021. Accessed August 24, 2022.
13. mSystems. High-fiber, whole-food dietary intervention alters the human gut microbiome but not fecal short-chain fatty acids. Published March 16, 2021. Accessed August 24, 2022.
14. Critical Reviews in Food Science and Nutrition. High-fat or high-sugar diets as trigger inflammation in the microbiota-gut-brain axis. Published April 8, 2020. Accessed August 24, 2022.
15. Nutrition Research. Food matrix and the microbiome: Considerations for preclinical chronic disease studies. Published February 27, 2020. Accessed August 24, 2022.
16. International Journal of Molecular Sciences. Artificial sweeteners negatively regulate pathogenic characteristics of two model gut bacteria, E. coli and E. faecalis. Published May 15, 2021. Accessed August 24, 2022.
17. Translational Psychiatry. Gut microbiota and voluntary alcohol consumption. Published April 7, 2022. Accessed August 24, 2022.
18. Journal of Translational Medicine. Influence of diet on the gut microbiome and implications for human health. Published April 8, 2017. Accessed August 24, 2022.
19. National Institutes of Health, Office on Dietary Supplements. Probiotics fact sheet for health professionals. Last reviewed June 2, 2022. Last accessed July 20, 2022.
20. Current Opinion in Behavioral Sciences. Stress, depression, diet, and the gut microbiota: human–bacteria interactions at the core of psychoneuroimmunology and nutrition. Published March 25, 2019. Accessed August 24, 2022.
21. Exercise and Sport Sciences Review. Exercise and the gut microbiome: A review of the evidence, potential mechanisms, and implications for human health. Published April 2019. Accessed August 24, 2022.