Guzzle, gobble, gulp. Gas, GERD, gut pain. We often take our guts for granted until something goes wrong. Bloating, abdominal pain, irregular bowel movements, and other aggravating symptoms are common problems with poor gut health.
If you’ve ever experienced IBS (irritable bowel syndrome) or traveler’s constipation, you know your gut means business. As a seasoned registered dietitian, I’ll provide you with the latest science of what to eat or avoid to get your gut back on track.
What’s in Your Gut?
Your gut is technically your GIT (gastrointestinal tract), an intricate system of organs starting in the mouth and ending in your large bowel. While the process of digestion starts with chewing, once foods are swallowed, most of the action is out of your control. There aren’t really ways to manage how things are digested or metabolized, but your diet and lifestyle can have profound effects on gut health.
The majority of your immune system (roughly 70%) resides in your intestinal tract and is affectionately known as the gut microbiome. This diverse collection of bacteria can either help or hinder your overall health. In short, poop matters! When you eat the right combination of healthy food, your gut bacteria will work for you, not against you.
Why Be Good to Your Gut?
Remember COVID-19? A robust gut microbiome and strong immune system help prevent communicable diseases including colds, flu, COVID, and more. One study found that COVID symptoms were worse in individuals with poor gut health scores. Other research also supports the theory that a weak microbiome is linked with increased severity of COVID.
Your gut microbiota could also be the cause of autoimmune diseases: chronic conditions such as rheumatoid arthritis or MS that are driven by heredity, environment, and a faulty immune system.
A meta-analysis of studies shows a link between the gut microbiome and rheumatoid arthritis. Certain foods impact the gut to either increase or decrease inflammation, which drives disease. Another study found a relationship between certain bacteria in the gut microbiome and the development of type 1 diabetes and celiac disease.
Changes in gut bacteria may also be responsible for mental health disorders including bipolar disorder, anxiety, eating disorders, and depression. Remember, the brain-gut axis means your gastrointestinal and nervous systems are connected.
Your microbiome also impacts metabolism and the risk for obesity, heart disease, and diabetes. One study found that a Mediterranean diet lowered cholesterol, improved insulin sensitivity, and altered gut microbiota compared to a Western-style diet. More reasons to eat more plants, and less processed and fast food.
Pre and Probiotics
You’ve likely heard that probiotics can improve your gut microbiome. Probiotics are active bacteria that help your body digest food, make vitamins, and get rid of disease-causing compounds. Yogurt as well as other fermented foods including kombucha, kimchi, kefir, miso, sauerkraut, tempeh, and natto (fermented soybeans found in Japanese cuisine) provide probiotics.
Prebiotics are “food” for probiotics. Prebiotic foods contain fiber and include foods such as artichokes, asparagus, bananas, garlic, and onions. Including these foods on a regular basis will provide fuel to support probiotic production. Inulin is an example of a prebiotic fiber.
Pre and probiotics also come in supplement form and may be valuable in some conditions. My client Sarah, a 47-year-old CEO of a mid-sized company, suffered from IBS that got worse after she got promoted. She complained of abdominal pain, gas, and intermittent diarrhea after most meals. She became fearful of travel because she never knew how her gut would react.
I had Sarah keep a food diary to see if certain foods might aggravate her condition. She noticed that raw onions, fried foods, certain fruit, and alcohol made things worse. She cut these out of her diet, added more soluble fiber from oatmeal, bananas, and brown rice, and also started a probiotic supplement. Her symptoms improved within six weeks of diet changes and supplement use.
Probiotics have been found to be useful in IBS patients. In a meta-analysis of studies, a probiotic containing B.coagulans was found to reduce abdominal pain, bloating, and discomfort in IBS patients. Treatment of eight weeks was suggested in the study.
The type of diet changes Sarah made have been validated in people with ulcerative colitis. A small study of 17 patients found that a high-fat diet increased inflammation while a low-fat, high-fiber diet containing lots of fruits, vegetables, and whole grains reduced inflammation and symptoms of ulcerative colitis.
Probiotics may also help older adults with reducing cognitive decline and mood changes. A study of 63 adults (over age 65) found that after 12 weeks of probiotics versus placebo, the amount of inflammation-causing gut bacteria was significantly reduced in the probiotic group. The probiotics used in this study contained Bifidobacterium bifidum BGN4 and Bifidobacterium longum BORI.
Prebiotics have also been studied in the prevention and treatment of disease, but the results are mixed. One study on inulin found that it helped increase Bifidobacteria but had no impact on improving insulin sensitivity, which would help prevent diabetes.
Prebiotics used in combination with probiotics are called synbiotics, and may be effective in improving blood sugar. A meta-analysis of individuals with gestational diabetes and those with prediabetes found improved blood sugar with the use of this supplement combination. It did not improve blood sugar in those with type 1 diabetes.
Best Foods to Fuel Your Gut
If I had to choose one thing to eat to fuel my gut it would be FIBER. It’s the indigestible part of plants that gets fermented and makes bacteria in your gut. The reason you get gassy after eating beans, certain fruit, and sometimes dairy products is that fermentation creates gas. The carbohydrates (from fiber and lactose in dairy products) are usually the culprit but that’s not necessarily a bad thing.
Since fiber isn’t digested, it gets moved through your gastrointestinal system and is eventually expelled from your colon (large bowel) in the form of stool. Fiber also makes short-chain fatty acids (SCFA) in your bowel. These SCFAs assist with creating bacteria that helps digest food, create vitamins, or fight disease.
Research suggests that short chain fatty acids aid in preventing gastrointestinal dysfunction, obesity, and type 2 diabetes. Switching from low-fiber to high-fiber foods may aid in weight management as well.
My 33-year-old client Scott was trying to lose weight by cutting out carbs, but would end up overeating them on the weekends with pizza, beer, and sweets. He also complained of constipation on a keto diet. His weight went up and down. Rather than cutting out carbs, I suggested he eat a moderate amount and switch to whole grains, more vegetables, beans, and fruit in his diet.
He made the changes gradually by using brown rice in place of white, whole-grain pasta and bread, and adding black beans to his salads. He chose fruit for dessert and added veggies to most meals. Scott felt fuller after eating and was able to curb his sweet tooth. After 10 weeks, he lost 12 pounds and noted his bowel function was much more regular.
When adding more fiber to your diet, don’t forget about water. Fiber attracts water to bulk stool and moves it through the intestines to be expelled. Aim for at least eight, 8-ounce cups of water daily for adequate hydration. Remember, what goes in must come out!
Keep in mind you might get gassy. A small study in healthy men found that compared to a Western-style diet, a high-fiber, Mediterranean diet produced more gas, sensations of gas, increased gassiness after a meal, and larger colonic stool content. Gas. Is. Normal.
Worst Foods for Gut Health
“Garbage in, garbage out” certainly applies to your gut. These foods and drinks can have negative impacts on your gut:
Sugar and artificially-sweetened drinks
Red meat in excess
Highly processed foods such as hot dogs, fast food, sweetened beverages, and processed snack foods change your gut microbiome, increase inflammation in your gut, and potentially lead to diseases including cancer, diabetes, and obesity.
A study on mice found that feeding them a Western-style diet impaired intestinal immunity and raised the risk of obesity, pre-diabetes, and metabolic syndrome.
Go easy on red meat to protect your gut. Red meat has been found to alter the gut microbiome and increase inflammation, while plant-based proteins have anti-inflammatory effects.
The Colonic Mucosal Barrier is the barrier between the colon and the rest of the body. It protects the body from bacteria and toxins, and lets water, ions, and nutrients pass through. This barrier is protected by colonic mucus. One study found that eating a lot of red meat thins colonic mucus (reducing protection); high whole grain intake does as well, but to a lesser extent.
Fried meat can also be harmful to your gut. A study on overweight and obese individuals found that those consuming higher amounts of fried meat had increased intestinal inflammation and endotoxin production (bad bacteria). This led to worse blood sugar management. Stick with grilled, baked, or broiled meat, and keep it lean.
As a toxin, excessive alcohol intake is associated with an altered gut microbiome and can have negative effects on the gut-brain axis balance. This may impact neurotransmitters in the brain that affect behavior and mood.
Final Thoughts on Best Gut Health
Your best defense in protecting your gut is to:
Eat a high-fiber diet with a variety of plant-based foods including fruit, vegetables, beans and lentils, whole grains, nuts, and seeds. Adult women need about 25 grams of fiber daily, while men should aim for nearly 40 grams of fiber per day for overall health. Diets high in fiber are linked with a lower risk of diabetes, obesity, heart disease, and certain types of cancer, such as colon and pancreatic cancer.
Add fermented foods to your diet, and ask your doctor or dietitian if a probiotic is appropriate for you. There are multiple strains of probiotics and more research is needed in this area; I don’t recommend that you just buy any probiotic from the store and start taking it.
Cut back on highly processed foods including processed red meat, fast food, and processed snacks. Limit or avoid sugary drinks and alcohol, and be sure to drink plenty of water — especially as you add more fiber to your diet.
Slow down when you eat. Eating too quickly makes you swallow more air, which can increase gassiness and bloating.
Finally, get enough sleep. Sleep deprivation has been associated with altered gut microbiome composition, which may impact metabolic processes including digestion and blood sugar control. Seven to eight hours per night is advised for most people.
For more tips on healthy eating, an expert can help. Reach out to a registered dietitian, or check out the Kickoff app’s nutrition features and learn how you can work with a certified expert to help you reach your health and nutrition goals.