Feeding Your Gut

If you want a healthy gut, you have to feed it well. This nourishment should include both probiotics and prebiotics — two dietary components that are increasingly being recognized as essential to your intestinal and overall health, says Teresa Fung, adjunct professorin the Department of Nutrition at the Harvard T.H. Chan School of Public Health.

There's been a lot of buzz recently about the need to eat probiotics — -living microorganisms found in foods such as yogurt and fermented vegetables. Probiotics add to your gut microbiota, the collection of 100 trillion or so bacteria and other critters living in your gut. Having a healthy microbiota may help foster a healthy immune system and reduce damaging inflammation in the body. Eating probiotics regularly may also help to prevent the intestinal environment from being overrun by unhealthy bacteria, which have been linked to everything from mood disorders and obesity to diabetes and neurodegenerative diseases.

But probiotics are much like pets, says Fung. It's not enough to just get one; you also have to take care of it, she says. This means feeding the population of microorganisms with prebiotics — foods that will help all of these desirable gut bugs grow and thrive inside your digestive tract.

Understanding your gut

To understand how to keep your intestinal environment healthy, it's important to understand how your microbiota evolves. Everyone has a unique mix of microorganisms living inside them. Some of these come from your mother, conferred during pregnancy, delivery, and, potentially, breastfeeding. Others are introduced by the foods you eat, and your environment.

Probiotics found in fermented foods and drinks — such as yogurt, cheese, kefir, kimchi, and sauerkraut — can add desirable organisms to your gut. But not all varieties of these foods have probiotics; it depends on how they are processed. Sometimes foods that naturally contain probiotics are then cooked or heated, killing the microorganisms and any potential health benefits along with them, says Fung.

Slipping an occasional food with probiotics into your diet won't do much to help you improve your microbiota, says Fung.

"Eating probiotics needs to be a regular thing," she says. (Research hasn't yet determined the ideal frequency.)

Try adding them into one or more daily meals for the biggest benefit. Sip a yogurt smoothie for breakfast, or put a forkful or two of sauerkraut alongside your sandwich at lunch.

The need for prebiotics

Even if you eat a lot of foods that contain probiotics, it won't do you much good if your intestinal environment doesn't allow them to prosper, says Fung.

Research has shown that a traditional Western diet — heavy on fat, sugar, and animal meat — creates a toxic environment for healthy microbes and can even change the proportion of different types of bacteria inside your body, she says. In short, your healthy gut microbes will suffer on a diet of hot dogs and French fries.

What beneficial bacteria love, says Fung, is fiber. When fiber enters your digestive system, enzymes from the microbiota help to break it down, producing substances called short-chain fatty acids. Experts think that having more of these fatty acids changes the pH inside your colon, making it less hospitable to some damaging types of microorganisms.

Some good prebiotic options are beans and whole grains.

"Whole grains can include everything from oats to wheat," says Fung.

Vegetables and fruits also contain healthy fiber. Other good prebiotic sources include garlic, bananas, onions, asparagus, and seaweed.

Over all, the goal should be to make sure your diet contains a good balance of probiotics and prebiotics. If you feed your gut well, it may repay you in better health.

This article originally appeared in the Harvard Health Publishing Women's Health Watch journal online.