What Are Prebiotics? Meet the Unsung Heroes of the Gut

healthy stomach

Ever since we heard about probiotics, those healthy live yeasts and bacteria that make our GI tract happy, we’ve been eating as much yogurt as we can get our hands on.

But have you heard about prebiotics–the food for probiotics? And are you getting enough?

What Are Prebiotics?

“Prebiotics are the unsung heroes of the gut,” according to Nadia Tarazi, the Founder and CEO of MicroNourish. “Most people now understand the importance of probiotics, or healthy bacteria, in supporting health and wellness. However, the vital role that prebiotics play in sustaining gut health is often overlooked.”

Some might be worried that prebiotics are just another foodie trend — after all, how many new “health” crazes crawl out of the woodwork every few months? But Joe Leech, RD and nutrition writer at DietvsDisease.org and AuthorityNutrition.com is ready to set us straight. “There are so many gimmicks when it comes to nutrition, but prebiotics is not one of them,” he says.

So what are they?

To answer this question, Rafael Avila, Manager of Research and Development for Natural Organics, Inc, ddescribes the key qualities of probiotics as follows: “1) it is a form of fiber (non-digestible carbohydrate), 2) it is beneficial, 3) it selectively stimulates the growth and/or activity of one of a number of [good] bacteria in the gut.”

In other words, prebiotics are essentially fiber that is consumed by bacteria – and not just any bacteria, but probiotic bacteria — the ones we’ve been trying to get more of. Dr. Roshini Raj, a gastroenterologist and a co-founder of TULA skin care line, says that “we all contain over 400 species of probiotic bacteria in our digestive tract, which reduce the growth of unfavorable bacteria and promote a healthy digestive system, increasing vibrancy and overall health.”

“Prebiotics, on the other hand, are indigestible dietary fibers that act as food for probiotics,” she explains.

In other words, prebiotics are there so that probiotics have something to eat once they get to your gut, keeping them healthy and allowing them to do their job.

Why Are They Important?

For Mike Clark, Ph.D., Director of Education & Research at Natural Bio Health, it’s impossible to say whether prebiotics or probiotics are the more important organism. “They are both equally beneficial to the body if you know for sure that the probiotic you are using reaches the large intestine and small intestine where the healthy bacteria does its work,” he says. As opposed to probiotics, which are aversely affected by heat, stomach acid or time, “prebiotics increase the number of healthy bacteria in the gut. Prebiotics are generally not affected by heat, cold, acid or time,” he says.

In short, probiotics and prebiotics exist in symbiosis.

According to Mike, “Fiber and prebiotics in fiber are important to a healthy colon and healthy gut. 70% of our immune system is in the gut. 90% of serotonin is produced in the gut. Prebiotics increase calcium absorption and bone density. They also help with weight management, correction of dysbiosis (bad colon bacteria), leaky gut and endotoxemia (toxins in the blood).”

Some say that prebiotics may even help with childhood obesity problems and with managing IBS. Everything you’ve ever heard attributed to either the consumption of soluble fiber or the consumption of probiotics would not be possible without prebiotics.

Why Have We Never Heard About Them?

Given how important they are, it seems strange that this is the first that many of us are hearing about prebiotics, but the experts have known about them for a while. Yousef Elyaman, MD, IFMCP says, “I prescribe prebiotics all the time. They are necessary to overall health.  Any condition that would require probiotics would benefit from prebiotics.”

Brian Prather of Bedford Wellness Pharmacy says he isn’t quite sure why prebiotics have stayed out of the limelight for so long. “Perhaps becuse the supplement companies worked so hard to promote probiotics. As their value became apparent, the health media picked up on it and ran with it. Pre-biotics  are a lot more work to incorporate into your diet, and they just play a supportive role to the probiotics. They’re not as sexy. Everybody loves the quarterback. We tend to ignore the offensive line, that protects the quarterback and allows him to do his job.”

This is one major possibility, and one of the dangers of following health trends without doing sufficient research to back up your findings. Mike has a slightly more critical view of why prebiotics have been so absent from the health news media for so long that stays in the same vein. “Millions are spent to advertise the probotic health benefits of yoghurt,” he says. “Activia is one even though it is sour milk and not a yoghurt. Millions are also spent on different brands of Greek Yoghurt, Bulgarian Yoghurt, etc. Prebiotics are fiber and the products are not there to market like in probiotics. The can be purchased in powder and pill form but the big $ are not there.”

But there may be an even more serious reason according to Tehzeeb Lalani, the Mumbai-based nutritionist behind Scale Beyond Scale. “Probiotics are gaining momentum recently because our current lifestyles are such that we inevitably destroy the ‘good’ bacteria in our stomach,” she says, citing antibiotic, alcohol and acidity consumption as the main culprits, as well as an excess of bad bacteria from processed foods overpowering the good bacteria we want.

Says Yousef, “I think many times we just want a magic pill.” Well, as we all know, there is no magic pill. But now that we know about prebiotics, we can start allowing them to contribute to the good health of our probiotics and our guts.

Which leads us to our next question…

How Can We Make Sure We’re Getting Them?

We’ve established that prebiotics are basically soluble fiber, but that’s not the beginning and the end of the story. According to Rafael, “There are forms of prebiotic fiber lurking everywhere, and yet they are still elusive.”

According to a study that he references, “inulin and oligofructose are two major forms of prebiotic fiber. But the study describes forms of each kind of such fiber as having prebiotic activity only when they occur in a certain range of molecular sizes. (…) So the bottom line is that each form of fiber must be studied in order to determine if it actually has prebiotic activity.”

But we’re not going to study our fiber every day to make sure we get enough – so are there any ground rules to make sure that we’re getting the right kinds of fiber to best benefit probiotics?

Well, let’s start with the good news, according to Tehzeeb, who points out that one other reason we might not be hearing so much about prebiotics is that they’re far more common than probiotics. “Prebiotics aren’t of huge focus because most fruits and vegetables contain prebiotics which most of us consume anyway because they offer fiber and an array of other micronutrients. Our diet may not always have probiotics though since they are mostly found in yogurt and fermented foods.”

Joe agrees with Tehzeeb, noting that it’s easy to consume enough probiotics — provided you know what you’re looking for. “In this case, you want to regularly eat fermentable fiber,” he says. Which, if you don’t know already, should send you straight to the beans and legumes section of your local supermarket.

“But we all know the saying about beans, and it’s true,” says Joe. “One of the by-products when bacteria ferments fiber is gas. This is the reason legumes can cause flatulence and stomach discomfort. It’s somewhat of a sign that your gut bacteria are enjoying their meal.”

Roshini highlights a few other known sources of prebiotics, including whole grains, asparagus, leeks, onions, garlic, soybeans, dandelion root or Jerusalem artichoke. To this list, Mike adds apple skin, bananas and chicory root. Some even believe that there may be useful prebiotic fibers in coffee grounds. “However,” Mike notes, “Most of the foods contain small amounts of the fiber, usually 1 to 2 grams per serving.” And that’s far from enough if you’re only eating it in bits and pieces; you should be aiming for between 25 and 30 grams a day.

“The rule of thumb is: Read your labels when you shop and look for items with a good blend of soluble and insoluble fiber,” says Brian. “If you can get at least 10gm in the form of soluble fiber, you should be well on your way to supporting the growth and sustenance of your probiotic supplement.”

The last important thing to bear in mind is that, when possible, it’s a good idea to eat both prebiotics and probiotics at the same time. As Joe says, “Consuming probiotics without prebiotics is like growing flowers without water.”

Some companies are launching new products to market to this desire to consume both at once. Hamilton Colwell is the Founder and Creator of Maia Yogurt, one of the only yogurts on the market to include prebiotics and probiotics in the same bite. “They are not typically found in yogurt but we add a prebiotic dietary fiber to Maia Yogurt to increase the efficacy of the probiotics,” he says. “Many foods marketed as containing probiotics (100 Million!) do not necessarily include a mechanism to keep the probiotics alive as the product sits on the shelf before it reaches your fridge, much less your mouth.”

While the science is not yet conclusive, explains Rafael, “We’re left with common sense. And the common sense answer is that it seems reasonable that taking them at about the same time would be helpful. Probiotics are living creatures, and they experience stress when they travel through your GI tract. Billions die throughout the journey. So it would make sense to make sure that the survivors find plenty of food (prebiotic fiber) when they finally come upon a nice place of intestinal real estate upon which to settle down and call home.”

One thing’s for sure: you’ll soon be hearing quite a bit more about this cousin to probiotics, as the news media picks up on these scientific studies. Soon, you’ll also be finding loads of capsules and ways to integrate this fiber into your system.

But if you follow the guidelines and trust whole foods, you’ll soon be getting more than enough of both prebiotics and probiotics in your daily diet.

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Stomach image via Shutterstock: Africa Studio

Emily Monaco
Emily Monaco

Emily Monaco is an American food and culture writer based in Paris. She loves uncovering the stories behind ingredients and exposing the face of our food system, so that consumers can make educated choices. Her work has been published in the Wall Street Journal, Vice Munchies, and Serious Eats.