Prebiotics: Everything You Need to Know for A Healthier Microbiome

prebiotics

You hear a lot about probiotics these days, but what about prebiotics? What’s the difference between prebiotics and probiotics and should you be consuming both? In this article, we’ll cover everything you need to know about prebiotics.

What Are Prebiotics?

Prebiotics were first defined in 1995 as “non-digestible food ingredient that beneficially affects the host by selectively stimulating the growth and/or activity of one or a limited number of bacteria already resident in the colon.” (1)

That definition has been tweaked throughout the years and the latest update to the definition (decided on by the International Scientific Association for Probiotics and Prebiotics (ISAPP)) is as follows: a prebiotic is “a substrate that is selectively utilized by host microorganisms conferring a health benefit.” (2)

But let’s put this in plain English, shall we?

A prebiotic “feeds” your healthy bacteria and, as a result, benefits you and your body. Prebiotics can be found in both foods (typically high-fiber foods) and supplements.

While “classic” prebiotics such as fructooligosaccharides and galactooligosaccharides still fit this new definition, this expanded criteria now also allows some non-carbohydrate nutrition components such as polyphenols (a type of antioxidant) to be classified as prebiotics.

What’s the Difference Between Prebiotics and Probiotics?

Prebiotics and probiotics are quite different, despite very similar-sounding names!

While a prebiotic “feeds” good bacteria in your microbiome and offers you benefits in return, a probiotic is a live organism that beneficially impacts your body. (3)

You can think of a prebiotic as the fuel for probiotics, which are the live bacteria that need feeding.

Probiotics can be found in food sources like yogurt, kefir, kvass, sauerkraut, and more. Prebiotic food sources include chicory root, garlic, onion, Jerusalem artichoke, and more.

You can consume both probiotics and prebiotics in supplement form. (We’ll talk about the best prebiotic supplements in just a moment.)

Both probiotics and prebiotics are exceptionally good for you, and I highly recommend incorporating both into your routine for best results. If you’d like to learn more about probiotics, check out my article on the topic here.

What’s the Difference Between Prebiotics and Fiber?

Many prebiotics are considered a type of fiber, so you will often see the term “prebiotic fiber” used.

That said, not all types of fiber are considered prebiotics. The main difference between a prebiotic and fiber is what kind of bacteria they feed.

A prebiotic must selectively feed beneficial bacteria, whereas fiber is metabolized more broadly and thus can feed non-beneficial bacteria as well as good bacteria. (Note that this doesn’t mean that fiber isn’t good for you — it just acts somewhat differently from prebiotics.)

While prebiotics and fiber are very important parts of a healthy diet, remember that not all fiber is considered a prebiotic.

Prebiotic Benefits

Prebiotics are a powerhouse when it comes to improving your health.

Here are some of the benefits of prebiotics you can expect.

Prebiotics & Digestive Health

Because prebiotics selectively feed healthy bacteria, they can be used to help correct “dysbiosis” or imbalanced gut bacteria.

There are two main types of dysbiosis: general imbalance, and insufficiency dysbiosis.

General imbalance is when you have too few beneficial bacteria and overgrowths of one or more commensal bacterial strains. Commensal bacteria are bacteria that are normal to find in small amounts and typically don’t cause any harm to you. However, when they start growing in high amounts, you might start developing symptoms.

Insufficiency dysbiosis occurs when you don’t have enough beneficial bacteria like Lactobacillus or Bifidobacteria hanging out in the large intestine. These should be present in high amounts, but it’s very common to see folks with very little or no growth of these beneficial microbes. In the case of insufficiency dysbiosis, you do not need to have any bad bacteria species overgrowing.

Dysbiosis has been associated with a myriad of health conditions, like allergies, eczema, metabolic syndrome, obesity, inflammatory bowel disease, autoimmunity, and more. You can learn more about dysbiosis by reading my article on the topic here.

By consuming prebiotics, you can increase your counts of beneficial bacteria which improves the balance of your microbiome. A balanced microbiome means a healthy body!

Prebiotic supplementation has been shown to improve lactose tolerance in those who are lactose intolerant, as well as improve symptoms of IBS like bloating, excessive gas, diarrhea, and constipation. (4, 5)

Prebiotic supplementation can also improve IBS-like symptoms even more than a low-FODMAP diet alone when combined with this approach. (6)

Prebiotics, Weight Loss & Metabolic Function

Gut bacteria play a huge role in how your metabolic system functions. When gut bacteria in the microbiome become imbalanced (i.e. you have “dysbiosis), you can develop systemic low-grade inflammation, often referred to as “metabolic endotoxemia.” This is when toxic molecules such as lipopolysaccharides (LPS) get through a “leaky gut” into your bloodstream.

Researchers believe that this inflammation is at the root of many diseases, but it can especially impact the development of metabolic disorders such as obesity and diabetes. (7, 8)

Taking prebiotics has been shown to improve fasting blood sugar, HbA1c, fasting insulin levels, and inflammation markers. (9)

Prebiotic intake has also been shown to increase satiety and decrease calorie intake, which may play a role in some of the positive metabolic changes seen with prebiotic consumption. (10)

Prebiotics & the Immune System

More than 70% of your immune system is housed in your digestive tract. (11)

This makes sense when you think about it — after all, your digestive tract is exposed to the many foods, particles, bacteria, etc that make it through your mouth on a daily basis. In order to keep you healthy, it must have a robust system in place to tolerate foreign particles that pose no pathological threat, while also being able to mount an attack toward pathogens that may negatively impact the body.

Prebiotics have been shown to positively impact the immune system. Prebiotic consumption increases short chain fatty acid (SCFA) production, which in turn has been shown to promote T regulatory (Treg) cells, as well as other important immune cells. (12) Treg cells have a balancing effect on the immune system because they discourage autoimmunity (the attack of your own body’s cells).

Because of these effects, prebiotic supplementation has been shown to improve atopic diseases such as asthma and eczema. (13, 14)

Prebiotics & The Brain

The gut and the brain are intimately connected — your brain “talks” to your gut and vice versa. At least on a subconscious level, we’ve known about this connection for a long time as evidenced by our use of phrases like “gut feeling,” “gutsy,” and “gut instinct,” but research is just starting to truly realize the extent of the connection between the brain and gut. (15)

Targeting the microbiome with microbiome-modulating things like prebiotics and probiotics is of great interest to researchers who study stress-related diseases such as anxiety, depression, and even conditions like irritable bowel syndrome.

Supplementing with prebiotics has been shown to reduce waking cortisol response in adults. (16) In mice, prebiotic supplementation also shows antidepressant and anxiolytic effects. (17)

Because this is such a new field of study, I expect that we’ll see lots more about the effect prebiotics can have on our mental health in the coming years!

Prebiotic Side Effects

There are very few side effects of consuming prebiotics. That said, some people may experience slight increases in bloating when consuming large doses of prebiotics.

To avoid any digestive upset, it is best to start slow when increasing your intake of prebiotics. Over time, your bacteria get used to having more and more fuel and you generally won’t experience digestive upset anymore.

Types of Prebiotics

There are many substances that act as prebiotics, and the list will surely become even longer in the coming years with the new, expanded definition of a prebiotic.

Some popular prebiotics include:

  • Inulin
  • FOS (Fructooligosaccharides)
  • GOS (Galactooligosaccharides)

With the expanded definition of prebiotics, there are some newer prebiotics available now as well, such as Sunfiber (also known as partially hydrolyzed guar gum or galactomannan fiber) and polyphenols.

Polyphenols are naturally-occurring compounds found in in plants. Some foods high in polyphenols include blueberries, coffee, strawberries, blackberries, flaxseed, tea, and wine. Recent research has shown that polyphenols act as prebiotics in the digestive system, increasing our counts of healthy gut bacteria. I’ve written a whole article on this topic, so make sure to check that out here.

Prebiotic Foods

Prebiotics can be found in both foods and supplements.

Here is a list of foods that contain prebiotics (including polyphenol prebiotics):

  • Apples
  • Asparagus
  • Blackberries
  • Blueberries
  • Burdock root
  • Coffee
  • Chicory root
  • Chocolate (dark)
  • Dandelion greens
  • Flaxseed
  • Garlic
  • Jerusalem artichoke
  • Jicama
  • Leeks
  • Onions
  • Peach
  • Pear
  • Strawberries
  • Tea
  • Wine
  • Yacon root

Best Prebiotic Supplements

I’m a big fan of including prebiotics both from the diet and incorporating a prebiotic supplement.

Here are a few of my favorite prebiotic supplements on the market. Remember to start slow and ramp up your dosage over time to avoid digestive complaints, no matter what prebiotic you take!

Bimuno (B-GOS)

Bimuno is a prebiotic GOS (galactooligosaccharide) supplement. It’s generally very well tolerated, even by those with digestive issues. I typically recommend 1 stick of the powder formula (3.6g). Bimuno can be mixed into pretty much any beverage and is tasteless.

Sunfiber

Sunfiber is a new (and pretty unique) prebiotic fiber supplement. It is certified low-FODMAP by Monash University, so it’s a great choice for those who are FODMAP intolerant. It’s also been shown to improve clearance rates of SIBO (small intestinal bacterial overgrowth) when combined with the typical antibiotic treatment for this condition. (18) I generally recommend 6 grams of Sunfiber per day for best results. Sunfiber mixes in with hot or cold beverages easily and is tasteless and colorless.

FOS

I like NOW’s Nutraflora FOS supplement. In general, I find FOS to be slightly less well-tolerated than the others on this list, but not by much! It’s got a nice sweet taste — I generally just dump it into my mouth and let it dissolve. I recommend 5 grams of FOS for best results.

What to Avoid in a Prebiotic Supplement

As prebiotic supplements become more popular, I’ve started to see lots of products claiming to contain prebiotics when they either don’t contain a substance that actually fits the definition of a prebiotic or they contain so little prebiotic that it is almost guaranteed not to actually benefit you when you take it.

Many supplements and foods claim to contain prebiotics when in reality they just contain fiber, so keep an eye out for that. Remember that fiber is absolutely great for you, but in my opinion it’s a bit of false advertising to claim that a fiber product contains prebiotics (unless, of course, that fiber is shown to be prebiotic).

You’ll also want to watch out for prebiotic supplements that contain extremely low doses of prebiotics. This typically happens in “synbiotic” products, which means that they include both a probiotic and a prebiotic. There is usually a tiny amount of prebiotic which does absolutely nothing for you as a human being, but can possibly increase the survival of the probiotic you’re taking. If you’re taking a prebiotic to benefit you, you’ll be taking grams of the stuff, not milligrams. Prebiotics are most often powdered supplements or quite a few capsules, since you need to take a lot for a therapeutic dose.

Lastly, prebiotics do seem to be somewhat like probiotics in that different types of prebiotics may be better suited for different uses. (Remember that the effects of probiotics are strain-specific.) Further research in the area will elucidate which prebiotics are most beneficial for different conditions.

The Bottom Line

Prebiotics feed the beneficial bacteria in your gut, which in turn make you healthier. Prebiotics are found in both foods and supplements, and it’s a good idea to take both to ensure you’re properly fueling your microbiome.

Be wary of supplements that contain milligrams of prebiotics — while they may benefit probiotics contained in the supplement you’re taking, it’s not a therapeutic dose for you. If you want the benefits of consuming prebiotics, you generally need to take grams of the stuff!

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