What are Prebiotics?

Nutrition Diva and special guest Ask Science discuss the difference between probiotics and prebiotics and why you need both in your diet.

Monica Reinagel, MS, LD/N, CNS
4-minute read
Episode #195

What are Prebiotics?

by Monica Reinagel, M.S., L.D./N. and Lee Falin, PhD

Nutrition Diva fan Niki writes:

“Monica, can you explain the difference between probiotic and prebiotic foods, and where cheese and wine fit in?”

As far as I’m concerned, Niki, cheese and wine fit in right around 6pm or so, while I’m making dinner. Or, if you’re feeling continental, wine and cheese also fit in well after dinner, instead of dessert!

See also: Why the French Don’t Get Fat


Seriously, this is a terrific question—because many people don’t realize that both cheese and wine (as well as beer) are good sources of probiotic bacteria. Probiotics, of course, are friendly bacteria that normally inhabit the human digestive tract, where they perform all kinds of useful tricks—such as helping to digest our food and protecting us from harmful bacteria. Probiotic bacteria even manufacture vitamins for us—including vitamin K and B12. In fact, up to 3 pounds of your body weight actually consists of beneficial bacteria!

Check out Ask Science's recent episode on Gut Microbiota for more!

Which Foods Contain Probiotics?

Although we often think of probiotics mostly in terms of dairy products like yogurt or kefir, there are all kinds of other probiotic foods as well. There’s Japanese tempeh or natto, which are both made from fermented soy. There’s Korean kim-chi, Polish sauerkraut and all kinds of other naturally fermented vegetables and pickles. Wine and beer both contain probiotics, and so does cheese—particularly aged cheeses like parmesan, cheddar, or gouda. In fact, virtually every traditional cuisine features some sort of fermented or cultured food.

See also: Benefits of Fermented Foods

But why? What is it about probiotics that makes them so beneficial? For that, we’ll turn to my colleague Dr. Lee Falin, aka Ask Science. Lee, what is it about these microorganisms that make them so important to us?

*** An Ask Science Exclusive! ***

Thanks Monica! I’m glad to help answer your question.

Scientists have long known that the human gut is home to a variety of different species of bacteria, which play some role in human health. However, recent research has revealed that the interactions between our bodies and those of our tiny symbiotic friends are much more complicated and have potentially greater impact than we ever realized.

For example, scientists have recently discovered that certain types of gut bacteria are more likely to be present in individuals with obesity. Also, eating foods that are thought to promote the growth of “good” gut bacteria has been shown to cause weight loss, lower blood pressure, and lower heart rate.

Research on the interactions between this gut microbiota and human health have found links with not just obesity, but also Parkinson’s Disease, allergies, and many other conditions. One question that scientists all agree is difficult to answer is whether or not gut microbiota are responsible for these interactions or merely correlated with them. In other words, do the microscopic organisms living in our guts contribute to the cause of these conditions or are they there because of the conditions?

While more research is needed to answer that question, the role of microbes in controlling human health shouldn’t be easily dismissed. Consider the following statistics: While there are just over 20,000 protein-coding genes in the human genome, researchers estimate that there are somewhere between 5 and 8 million different genes in the various microbes that inhabit our bodies. That’s a potential ratio of 400 microbe genes acting in our bodies for every one of our own!

While not all of these genes would necessarily impact our bodies, even the possibility that a fraction of them could is cause for more research.


Wow, who knew there was so much going on in there? So back to Niki’s question.

What Are Prebiotics?

What’s the difference between prebiotics and probiotics? Prebiotics are substances that provide food for the friendly bacteria. Mostly, these bacteria feed on soluble fiber—a nutrient which we can’t digest or get any nutrition from. Eating foods high in soluble fiber keep our probiotic bacteria happy and healthy.

Certain foods, such as chicory root and Jerusalem artichokes, are particularly high in prebiotics. Of course, these foods aren’t exactly daily staples for most of us. Garlic, onions, and leeks—foods you’re likely to eat on a more frequent basis—are also relatively good sources. And smaller amounts of soluble fiber are found in a wide range of foods, including fruits, vegetables, whole grains, bran, honey, and soybeans.

See also: Soluble vs. Insoluble Fiber

Are You Getting Enough Prebiotics?

Lately, some food manufacturers have started adding prebiotics to packaged foods as a way of enhancing their health profile. Inulin and fructo-oligosaccharides (FOS) are two types of prebiotic fiber that are commonly used for this purpose. You even see them marketed all by themselves as prebiotic dietary supplements.

But, honestly, I don’t think you need to go out of your way to get prebiotics. As long as you’re eating a varied diet including plenty of fruits, vegetables, legumes, and whole grains, you should be getting enough soluble fiber to keep your beneficial bacteria happy. Certain probiotic foods, like wine and fermented soy, even come with their own built-in supply of prebiotics! Of course, that’s not a license to overdo it with the wine (or the cheese)!

See also: How Much Alcohol is Healthy

Keep in Touch

Thanks to Niki for suggesting this week’s topic. And big thanks to Ask Science for his insight. Make sure to sign up for his podcast to find out more about the fascinating world of science.

If you have a question you’d like me to answer in a future episode, send an email to nutrition@quickanddirtytips.com or post it on the Nutrition Diva Facebook Page.  I look forward to hearing from you!

I answer a lot of listener questions in my free weekly newsletter, so if you’ve sent a question my way, be sure you’re signed up to receive that.

Yogurt and bacteria images courtesy of Shutterstock.

About the Author

Monica Reinagel, MS, LD/N, CNS

Monica Reinagel is a board-certified licensed nutritionist, author, and the creator of one of iTunes' most highly ranked health and fitness podcasts. Her advice is regularly featured on the TODAY show, Dr. Oz, NPR, and in the nation's leading newspapers, magazines, and websites. Do you have a nutrition question? Call the Nutrition Diva listener line at 443-961-6206. Your question could be featured on the show.