What Happens to Your Gut Health When You Combine Fiber and Probiotics

Probiotics may bring good bacteria to your gut, but they won’t stick around too long without the right fuel. Adding variety to your diet—particularly fiber—is the secret to making lasting changes to your gut health.

Why You Need Fiber and Probiotics

Taking probiotics will help prime your gut for good health, but you also need to incorporate fiber-rich foods into your diet to make lasting changes.

“They’re kind of like tourists. They change the neighborhood for a little bit, but it doesn’t change the city as a whole,” Dawn B. Beaulieu, MD, IFM-CP, FACG, an associate professor of medicine specializing in gastroenterology at Vanderbilt University Medical Center told Verywell.

“You can’t use a probiotic in place of good nutrition," said Beaulieu. "You can’t out-supplement a bad diet.”

How Probiotics Affect the Gut Microbiome 

Probiotics, often called “good bacteria,” help maintain balance in the gut microbiomes. Think of your gut as an ecosystem with a large community of trillions of microorganisms. All these bacteria play essential roles in breaking down food and supporting the immune system.

Whenever the microbiome is altered, you can see changes in the health of your gut. For example, taking antibiotics tends to kill off some of those good bacteria, which can lead to diarrhea or constipation.

There is still a lot that's unknown about the gut microbiome, but recent studies suggest probiotics alone may not be enough to protect from infection.

Why You Need Fiber to Feed the Probiotics

Certain types of fiber, like inulin or fructooligosaccharides (FOS), serve as food for the good bacteria in your intestines. These prebiotic fibers feed the good bacteria and give them the energy to thrive.

When fiber is transformed into beneficial compounds like butyrate, these compounds help reinforce the protective barrier of the gut lining and boost immune function, said Allen A. Lee, MD, MS, a clinical lecturer specializing in gastroenterology at the University of Michigan Health.

As such, without enough fiber, the probiotics you take may not stay long enough for you to see real benefits.

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How This Combination Improves Gut Health

A recent study found that a strain of probiotics (Bifidobacterium animalis subsp. lactis), when combined with inulin, can increase good bacteria, reduce visceral fat, and improve vascular health. It may also help prevent the development of metabolic syndrome, including insulin resistance, obesity, and high blood pressure.

Another recent study found that eating fiber may even protect against cancer.

Combining probiotics with fiber-rich foods like fruits, vegetables, and whole grains creates the optimal environment for these helpful bacteria to flourish.

Because bacteria compete for surface area on the gut lining, filling that space with good bacteria leaves less room for bad bacteria to grow. This can reduce inflammation, improve digestion, and lower your risk of gastrointestinal illnesses.

How to Get More Fiber in Your Diet

Americans typically get two servings of fruits and vegetables daily, but they should be getting at least five.

Try to focus on three servings of some kind of fruit and vegetable at every meal, said Beaulieu. Ideally, you’d want to see about seven colors on your plate. With each color, you’re getting different properties and health benefits, she added.

“The more diverse foods that we eat, the more diverse our microbiome is and the healthier our gut is,” said Lee.