Probiotics and Prebiotics—Why You Need Both in Your Diet

Different milk products on a wooden table

keepingUnless you haven’t logged onto the Internet or walked through your local bookstore in the last couple years, you’ve probably heard about the importance of balancing the good and bad bacteria in your gut.

Cropped shot of a young sporty woman making a heart shape on her stomach outside

There are actually billions of beneficial bacteria inside of your body. These bacteria make up your microbiome, a complex ecosystem that is crucial for keeping your digestive system working properly, boosting your immunity, keeping your hormone levels balanced and supporting brain function. And although the bacteria that make up your microbiome can be found everywhere inside and outside of your body, the majority live in your digestive system—where around 80 percent of your entire immune system is also located. That means that your gut and, specifically, the good bacteria that live there, play a major role in the health of your entire body.

From the moment you are born, the good bacteria colonize in your gut, supporting the body’s various systems. But when the gut ecosystem goes through abnormal changes—due to stress, poor dietary and lifestyle habits, illness, the use of antibiotics and illness, etc.—you are more susceptible to health issues and disease. This is when the balance of good-to-bad bacteria gets out of whack. (1) And once allowed to grow rampantly, the bad bacteria can cause inflammation and illness throughout the body, triggering everything from leaky gut to psoriasis.

Experts agree that your gut flora should be made up of approximately 85 percent good bacteria and 15 percent bad or neutral bacteria. But keeping this delicate balance in place isn’t always easy, and sometimes we need a little help in the form of supplements. The key to establishing a healthy gut and digestive system—and keeping healthy—is to consume probiotics and prebiotics. Probiotics are the good bacteria that support your body’s ability to fight infections and keep you healthy. Prebiotics, meanwhile, are the fuel that help the good bacteria to thrive and keep bad bacteria in check.

The Role of Probiotics

The term probiotic means “for life” in the Greek language, and the United Nations World Health Organization defined them as “live microorganisms which, when administered in adequate amounts, confer a health benefit on the host.” (2)

The benefits of probiotics include their ability to support your immune, digestive, and neurological systems, and they also improve the health of your skin, crowd out bad bacteria, yeast and fungi in your gut and produce important nutrients like vitamin B12, vitamin K2 and butyrate.

Historically, we consumed plenty of probiotics in our diets. Our ancestors ate foods from good soil which naturally contained high levels of beneficial bacteria, and they also ate a lot of fermented foods that are also high in probiotics. Today, though, people aren’t getting enough probiotics in their regular diets, or they’re consuming too many foods that are highly processed or full of antibiotics, GMOs and other ingredients that kill the good bacteria in your body.

Different milk products on a wooden table

To counteract those effects, some of the best probiotic foods that you can add to your diet include:

  • Kefir (a thick yogurt-like drink traditionally made from cow’s milk)
  • Coconut kefir (made from coconut milk)
  • Yogurt
  • Raw cheese made from goat’s milk, sheep’s milk and A2 cow’s milk
  • Cultured vegetables, like kimchi and sauerkraut
  • Kombucha
  • Apple cider vinegar
  • Tempeh
  • Natto
  • Miso

Taking a high-quality probiotic supplement made from soil-based organisms can also be helpful in reestablishing proper levels of beneficial bacteria in the gut. But if you want to make sure those good bacteria have a chance to thrive and multiply, you need to provide them with the proper fuel.

The Role of Prebiotics

Prebiotics are a type of non-digestive fiber compound that actually feed probiotics. The best-known type is called “oligosaccharides,” and this is just one group of chemical compounds that are found in high-fiber foods.

When consumed, prebiotic compounds pass through the upper part of the gastrointestinal tract undigested because the body can’t break them down. They then move into the colon, where they are fermented by the gut microflora. During this process, the prebiotics act as sources of fuel for the nutrients in the digestive tract, including the good bacteria that live in your gut. (3)

Consuming prebiotic foods helps to balance the harmful bacteria and toxins that live in your digestive tract. Plus, when the probiotics in your gut metabolize the prebiotic fiber compounds as a source of their survival, they produce short-chain fatty acids that improve the health of your intestinal lining and help to regulate electrolyte levels in your body.

Raw asparagus on a wooden table

Some of the best sources of prebiotics include:

  • Under-ripe bananas
  • Raw asparagus
  • Raw garlic
  • Raw or cooked onions
  • Raw leeks
  • Raw Jerusalem artichokes (also called sunchokes)
  • Raw honey
  • Psyllium husk
  • Wheat dextrin

In short, probiotics and prebiotics work together to help maintain the health of your digestive tract, which plays a vital role in your overall health. These healthy bacteria, and the prebiotic fibers that feed them, allow for the proper balance of good and bad bacteria in the gut, which, in turn, improves the health of your immune and digestive systems, while also reducing inflammation, balancing your hormones, improving your body’s ability to respond to stress and lowering your risk of weight gain and obesity.


Dr. Josh Axe Josh is a doctor of natural medicine, clinical nutritionist, and author. He specializes in how the right nutrition has a positive influence on people's health. View all posts by Dr. Josh Axe