“Prebiotic” is a term that shouldn’t be confused with “probiotic,” although the two are indeed connected.
Prebiotic foods play an important role in maintaining a healthy body.
This form of dietary fiber promotes a healthy digestive system by stimulating your gut bacteria to produce nutrients that are then used by the colon. Short-chain fatty acids like acetate, propionate, and butyrate, in particular, can enter the bloodstream to boost energy production.
In this article, we’ll examine the function of prebiotics and provide you with a list of the best prebiotic foods.
In This Article:
What Is a Prebiotic?
A prebiotic is a type of soluble fiber. Fibers fall into either the insoluble or soluble category. Insoluble fiber cannot be digested or dissolved in liquid and passes through the body—this is the type responsible for fiber’s link to the volume and passage of bowel movements.
Soluble fiber also cannot be digested. But since it dissolves in liquid, it’s the type that your intestinal bacteria can absorb. They do this by eagerly breaking down prebiotics into short-chain fatty acids that they then use for fuel.
What Do Prebiotic Foods Contain?
Since prebiotics are not digestible by the human GI tract, the foods are commonly linked with dietary fiber. Prebiotics are largely comprised of these natural dietary carbohydrates.
It should be noted that while prebiotics are considered dietary fiber, not all fibrous foods can be considered prebiotics.
While dietary fiber can be broken down by most microorganisms in the gut, prebiotics can only be fermented by very specific classes of intestinal microorganisms.
Moreover, most prebiotics are classified as disaccharides and oligosaccharides, specifically fructooligosaccharides (FOS), galactooligosaccharides, isomaltooligosaccharides, xylooligosaccharides, transgalactooligosaccharides, and soybean oligosaccharides.
Polysaccharides may also be considered prebiotic. These generally include inulin, cellulose, reflux starch, pectin, and hemicellulose. Dietary fiber, on the other hand, includes all of the aforementioned polysaccharides, as well as gums, substances obtained from marine algae, and lactulose.
Prebiotic Foods List
Inulin and FOS are found in bananas, oats, berries, garlic, onions, asparagus, and various root vegetables. However, the average American diet only contains about a third of this—mostly from wheat or onion sources.
Some foods have natural prebiotics added to increase their nutritional value and help stimulate probiotic action. The probiotics naturally living in the gastrointestinal tract depend on prebiotics to survive and maintain a healthy system.
Recommended daily servings of prebiotics range from four to 15 grams or more. Higher intakes are typically reserved for those with existing digestive disorders.
For reference, here are the average inulin and FOS levels for 100 g of some of the best prebiotic foods:
- Chicory root: 41.6 g inulin and 22.9 g FOS
- Jerusalem artichoke: 18.0 g inulin and 13.5 g FOS
- Dandelion greens: 13.5 g inulin and 10.8 g FOS
- Garlic: 12.5 g inulin and 5.0 g FOS
- Leeks: 6.5 g inulin and 5.2 g FOS
- Asparagus: 2.5 g inulin and 2.5 g FOS
- Wheat bran: 2.5 g inulin and 2.5 g FOS
- Baked wheat flour: 2.4 g inulin and 2.4 g FOS
- Banana: 0.5 g inulin and 0.5 g FOS
The following table includes the average inulin, FOS, and fiber amounts of additional prebiotic foods per 100 g.
Except for wheat flour, these are all values for the foods in raw form. Cooking causes a loss of about 10% to 20% of a food’s prebiotic content. A simple way to improve your intake is to grab a banana on the way to work or maybe mix some more raw veggies into your salad.
Jerusalem artichokes and chicory root have some of the highest concentrations of inulin and FOS, so eating them is definitely recommended.
Which Is Better? Raw or Cooked Prebiotics
Prebiotics are important to maintain a healthy digestive tract. But as noted above, how the food is prepared can affect the effectiveness of the nutrients. All food cooked by methods such as steaming, broiling, baking, and boiling with water loses some form of its composition, dissipating the natural nutrition value.
It is best to eat prebiotics raw, in their natural state. Using these foods as an added side dish or dessert, or as a meal in themselves, can provide you with the nourishment required.
If you choose to cook a prebiotic food, steaming offers the lowest loss of nutrients.
Are There Any Downsides to Prebiotic Foods?
Prebiotics aren’t for everyone. While most people enjoy a healthy relationship with their gut flora, others aren’t as lucky. Those suffering from Small Intestinal Bacterial Overgrowth (SIBO) experience an overabundance of gut flora. Feeding them with prebiotic foods can amplify problems like constipation or diarrhea (sometimes both!), gas and bloating, and in extreme cases, malnutrition or dangerous weight loss.
Similar but more temporary symptoms can occur if those with regular gut flora amounts overdose on prebiotics. Fortunately, it takes over 30 g (1.06 oz) to reach these inadvisable levels, so there is plenty of safe wiggle room for those who want to go over the recommended daily amount.
In addition, there is one reported case of an anaphylactic reaction to the prebiotic inulin. Experts expect more reactions to be documented as inulin becomes more widely used by manufacturers in food products.
It’s important to keep in mind that prebiotics don’t only benefit your gut flora. If you’re already playing host to an unpleasant intestinal invader like a member of the Klebsiella family, then prebiotics could end up feeding them as well.
Do You Need a Supplement?
As important as they are, there’s a good chance you won’t need to take any extra prebiotic supplements to get your six grams per day.
A synthetic form of inulin is used in a surprisingly large amount of processed foods since it can serve as a substitute for sugar, fat, or flour. Synthetic inulin can be found in many dairy products, sports drinks, cereals, soups, or sauces.
Check your ingredient labels and do some quick mental math to see if you’re already taking enough. If you’re not, and can’t get the six grams from diet alterations, then a supplement may be right for you.
If you do decide to take supplements, be careful to start small and work your way up to your ideal dose. Gut flora doesn’t like sudden changes in diet, so giving them a dramatic boost in food could end up causing some short-term digestion problems.
The Benefits of a Prebiotic Shake
If you don’t have the time to create a healthy, prebiotic-rich meal, you can always make yourself a nice healthy shake. It is easy to combine both probiotics and prebiotics in the shake.
For best results, prepare the shake with yogurt or kefir—they are both loaded with probiotics and the taste will go nicely with the sweet fruit you add to it.
Remember, when you add one or more types of prebiotics to your shake they will help the probiotics to grow!
A few good prebiotic foods to add to your shakes include:
- Bananas: They are high in fiber and they taste fantastic.
- Apple cider: Only add a smidge of it, because you don’t want the shake to taste too sweet.
- Honey: Pure, unpasteurized honey is packed with natural prebiotics and will provide your shake with great taste.
As an added bonus, here is a healthy recipe for your prebiotic shake:
- 1 cup of plain yogurt or kefir
- 1/2 ripe banana
- 1/2 teaspoon of apple cider vinegar
- 1 to 2 teaspoons of honey
- 1 teaspoon of acacia gum
- 1/4 of sweet, ripe mango
- 4 small strawberries
- 4 to 6 tablespoons of orange juice
Combine all of the ingredients in a blender and blend until it’s smooth with no chunks.
Under-Recognized, but Important
It’s a shame so little is known about our gut flora, since the little bits we do know are fascinating. These guys are a private army that keeps our digestive tracts running smoothly and our bodies ticking along healthily and happily. But an army only marches on a full stomach. So, be sure to stay on top of your daily prebiotic foods intake to keep them well fed!
Consuming prebiotic food sources at every meal could go a long way to help your gastrointestinal tract maintain its good health. Up to 15 grams of prebiotics is recommended daily.
Prebiotic foods such as onions, leeks, garlic, dandelion greens, chicory root, asparagus, and bananas are good options for your diet. On your next trip to the grocery store, be sure to bring a copy of the prebiotic foods list above.
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