Everything You Need To Know About Prebiotics: A Doctor Explains

Board-Certified Internist By Vincent M. Pedre, M.D.
Board-Certified Internist
Dr. Vincent M. Pedre is a board-certified internist in private practice in New York City since 2004. He serves as medical director of Pedre Integrative Health, president of Dr. Pedre Wellness, and is the author of Happy Gut.

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As a medical doctor, I see countless patients eating an inflammatory diet, getting insufficient sleep, and taking antibiotics that adversely affect their gut flora—making them overweight, sick, and inflamed. Generally, I use prebiotics and probiotics to heal the gut because they work to restore friendly flora while providing numerous other health benefits like reducing the risk for type 2 diabetes and cardiovascular disease.

Probiotics get most of the glory, and they deserve it! They outcompete nasty pathogens like unfavorable bacteria, yeast, and parasites, becoming mainline defenders against increased intestinal permeability (leaky gut) and other digestive issues. To get therapeutic amounts of probiotics, I ask my patients to eat plenty of fermented foods like kimchee and unpasteurized sauerkraut, but also to take a quality probiotic supplement that contains billions (not millions) of colony-forming units (CFUs), which are used to measure a probiotic's potency.

Could prebiotics be more important than probiotics?

Although they get less attention, prebiotics may be just as important (or even more important) than probiotics for gut health. This is because they feed our friendly flora. These probiotic "backups" aren't digested or absorbed in your gastrointestinal (GI) tract; instead, they bypass your small intestine and head straight for your colon, where they promote a healthy gut environment.

Prebiotics fall under several categories, including fructans (also called fructooligosaccharides or FOS) and resistant starch. Each feeds different types of gut flora including the key probiotic strainBifidobacterium—that helps with bowel regularity. The general rule is that to get labeled a "prebiotic" an ingredient must resist small-intestinal absorption, be fermented by intestinal microflora (probiotics), and stimulate healthy gut flora.

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Here's how to supplement with prebiotics.

Powders (such as inulin, which can double as a sweetener) can be used to deliver therapeutic amounts of prebiotics. Another convenient way to boost your intake of prebiotics is resistant starch, such as potato starch, which works even if you're on a low-carb diet or don't do well with nightshade vegetables.

If you're calorie-conscious, you should know that some manufacturers assign prebiotics at 4 calories per gram. But that's not technically true. Because they resist digestion and get fermented in your colon, they actually only possess less than 2 calories per gram.

Some supplements even combine probiotics with prebiotics. While supplements are convenient, you can also get prebiotics from food. Raw chicory root is your best bet: Prebiotics compose about 65 percent of its total weight. Raw Jerusalem artichoke ranks second, with about 32 percent of total weight as prebiotics.

Create the ultimate prebiotic salad.

If you're throwing together a salad, toss in some raw dandelion greens. About a quarter of its weight is prebiotics, and it also supports liver and kidney detoxification. Bonus points for adding prebiotic-fiber-loaded chickpeas! While I don't recommend them for first dates, raw garlic and raw onions (including scallions) are also great prebiotic food sources. To optimize gut health, incorporate soluble-fiber foods like apples, lentils, ground flaxseeds, and nuts, which slow digestion and steady your blood-sugar response.

You should be fine with food, but if you use prebiotic supplements, especially powders, please go slowly. We lack the enzymes to break down fructans and other prebiotics, and too many at once can create abdominal bloating, gas, and pain. One of my favorite prebiotic-probiotic combos is coconut water kefir (grab the recipe below), which is both a delicious carbonated beverage and a tonic to balance your gut ecosystem.

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Coconut Water Kefir

Makes 4 cups


  • 3 tablespoons water kefir grains*
  • 4 cups pasteurized coconut water
  • 1 cup fresh strawberries or blueberries
  • 1⁄2 cup fresh lemon juice (optional)

* Water kefir grains can be found in natural-food stores or online at Amazon. With proper care, the culture can be used indefinitely to create probiotic-rich kefir. Your grains will not grow as quickly in coconut water as they will in a nice bath of nutrient-rich sugar. Refresh and reactivate the kefir grains in sugar water (1⁄4 cup sugar in 4 cups water) for 24 to 48 hours between batches of Coconut Water Kefir. The sugar water will keep the grains healthy for the long term.


  1. Place the water kefir grains and the coconut water in a jar. Cover the jar loosely with a lid or cheesecloth and allow the kefir grains to culture the coconut water for 24 to 36 (and no longer than 48) hours at room temperature.
  2. Once the culturing is complete (the mixture will have thickened), remove the kefir grains with a slotted spoon and store in a separate glass container filled with sugar water (as above) to keep the kefir grains alive and active.
  3. You may drink the Coconut Water Kefir by itself, but for an added twist, puree the cultured coconut water with prebiotic berries and lemon juice in a blender to your desired consistency. The Coconut Water Kefir will last 1 to 3 weeks in the fridge; when blended with the berries and lemon juice, it will last for 2 to 3 days in the fridge. Serve cold.

Better gut health can help you lose weight, reverse your risk for chronic disease, and give you more energy. For more information to build a healthier gut, get this free Quick Start Guide.

Vincent M. Pedre, M.D.
Vincent M. Pedre, M.D.
Vincent M. Pedre, M.D., medical director of Pedre Integrative Health and president of Dr. Pedre...
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Vincent M. Pedre, M.D.
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