We've all heard plenty about our gut microbiome and how important it is to good health. What you may not have heard is that exercise may be as important as any probiotic to build a good gut microbiome.

Just what is our microbiome? Our gut microbiota starts with birth and affects functions throughout the body. Literally trillions of bacteria live in our digestive tract and play an important role in our health. Of the thousands of species of gut microbes that live inside us, some are healthy -- and some are not.

The good gut bacteria break down food, manufacture vitamins and train our immune system. When we have more good bacteria than bad, our health improves. In the same way, imbalances in gut bacteria have been linked to obesity, mood disorders and altered immune response.

We know a balanced, healthy diet that includes high-fiber and fermented foods (sauerkraut, miso, kefir, kimchi, kombucha, yogurt) can help our gut bacteria thrive. Foods high in fiber -- like raspberries, artichokes, green peas, broccoli, chickpeas, lentils, beans, whole grains, bananas and apples -- help good gut bacteria grow. Other helpful foods include chicory root, leeks, onions, garlic, asparagus, whole wheat, spinach, oats and soybeans.

Two studies at the University of Illinois found evidence that exercise can change the composition of microbes in the gut. In the first study, scientists at the U of I and Mayo Clinic transplanted fecal material from exercised and sedentary mice into the colons of sedentary germ-free mice, which had been raised in a sterile facility and had no microbiota of their own. They found recipients of the exercised mouse microbiota had a higher proportion of microbes that produce butyrate, a short-chain fatty acid that promotes healthy intestinal cells, reduces inflammation and generates energy.

In the second study, the team tracked changes in the composition of gut microbiota in human participants as they transitioned from a sedentary lifestyle to a more active one -- and back again. Researchers recruited 18 lean and 14 obese sedentary adults, sampled their gut microbiomes, and started them on an exercise program during which they performed supervised cardiovascular exercise for 30-60 minutes three times a week for six weeks. Researchers sampled participants' gut microbiomes at the end of the exercise program and after another six weeks of sedentary behavior.

Fecal concentrations of SCFAs, in particular, butyrate, went up in the human gut as a result of exercise. These levels declined again after the participants reverted to a sedentary lifestyle.

The bottom line? Here's another reason to add daily exercise to your routine -- along with healthy eating habits and plenty of fiber. Your gut will be glad you did.

Q and A

Q: Do you need to refrigerate almond butter and peanut butter after opening?

A: Knowing when to refrigerate nut butters can be tricky. Your best bet is to read the label. If it says "refrigerate after opening," you need to do that. If you buy all-natural peanut butter, you'll want to store jars in the refrigerator. Processed brands of peanut butter are made to have a long shelf life, thanks to the addition of stabilizers like palm oil and hydrogenated oils, so once opened, they're fine to store in a cool, dry cupboard. The National Peanut Board says opened jars of commercial processed peanut butter can be stored in a cupboard for two to three months. After that, they recommend storing jars in the refrigerator, which extends shelf life by another three to four months. Unopened jars will last six to nine months in the pantry; however, be sure to check expiration dates.

RECIPE

We've been having a taste of fall temperatures lately in central Illinois. That, along with school starting, has me thinking of fall foods. I'm a big soup fan: it's typically low in calories, full of nutrients and easy to make. This one can be done in a Dutch oven or in a slow cooker. If using the slow cooker, add the rice 30 minutes before serving.

STUFFED PEPPER SOUP

Servings: 8

2 pounds ground beef or ground turkey

6 cups water

1 can (28 oz.) tomato sauce, no salt added

1 can (28 oz.) diced tomatoes, undrained, no salt added

2 cups chopped green peppers (can use red, orange, yellow for color/taste)

1/4 cup packed brown sugar

2 teaspoons reduced sodium beef bouillon granules (or alternative)

1 teaspoon pepper

2 cups cooked long-grain rice

Optional: chopped onion, minced garlic, and fresh basil to taste

In a Dutch oven over medium heat, cook and stir beef (or ground turkey) until no longer pink, breaking it into crumbles; drain. Stir in next 8 ingredients; bring to a boil. Reduce heat; simmer, uncovered, until peppers are tender, about 30 minutes. Add cooked rice; simmer, uncovered,10 minutes longer. If desired, sprinkle with chopped fresh parsley. Serves 8 (serving size: 1 cup).

Per serving: 337 calories; 24 grams protein; 30 grams carbohydrate; 14 grams fat (5 grams saturated), 70 milligrams cholesterol; 4 grams fiber; 13 grams sugar; 466 milligrams sodium.

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Charlyn Fargo is a registered dietitian with SIU School of Medicine in Springfield, Illinois, and the current president of the Illinois Academy of Nutrition and Dietetics. For comments or questions, contact her at charfarg@aol.com or follow her on Twitter @NutritionRD. To find out more about Charlyn Fargo and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.