Probiotics have been a natural health trend for several years with no sign of slowing down. According to market research firm, Statista, the probiotic supplement industry was worth $820 million in 2020, and is forecast to be worth nearly $1.5 billion by 2027. This figure does not include natural foods that contain probiotics such as yogurt and sauerkraut.

Proponents of probiotic supplements claim that taking these pills or powders that contain millions or billions of colony-forming-units (CFUs) of friendly microorganisms can improve gut health. The benefits of improved gut health not only include better digestion but also a more robust immune system. This is because roughly 80% of the immune system cells reside in the gastrointestinal tract. Increasing the amount of friendly bacteria in the gut may also help mitigate the severity of leaky gut, which is caused by the deterioration of the lining of the mucosal barrier that prevents undigested food particles and toxins from entering the bloodstream.

Moreover, having a healthier gut microbiome may result in enhanced cognitive function, mood regulation, and skin health, among other benefits.

But there’s more to the story about gut health than probiotics.

There are two other ‘biotics’ that play a critical role in the gut microbiome: prebiotics and postbiotics.

What are Prebiotics?

Prebiotics are also called prebiotic fiber. Think of prebiotic fiber as the preferred fuel source for probiotics. In order for probiotics, the friendly bacteria in your colon, to colonize and thrive, the microorganisms need to be fertilized just like food crops need healthy soil and water in order to grow.

Many people assume that just by taking a probiotic pill they can continue to eat a diet heavily consisting of highly-processed foods that are low in nutrient density. But as a 60 Minutes segment revealed, albeit possibly with bias, many probiotic supplements may be ineffective at colonizing the gut with more beneficial bacteria.

If the bacteria in the GI tract does not receive enough prebiotic fiber, they will literally starve and be unable to proliferate in the colon, which is where the overwhelming majority of bacteria in the gastrointestinal tract should live. (Some people have a condition called SIBO, which occurs when too much bacteria remains in the small intestine.)

Some high-quality probiotic supplements contain prebiotic fiber. The most common prebiotic fiber is FOS (fructooligosaccharide). FOS is not digested. Instead, it passes through the small intestine and ferments in the colon (large intestine). It’s in the large intestine that friendly bacteria feed on FOS, thereby supporting the growth of beneficial bacteria.

FOS, which is also called inulin fiber, is not well-tolerated by everybody, however. For some people, including those with SIBO or Irritable Bowel Syndrome (IBS), FOS and other prebiotic fibers cause bloating and other digestive disturbances. That’s because of two reasons: fiber attaches to water in the gut and ferments. These two actions can worsen the severity of SIBO or IBS.

However, for many people, prebiotic fiber promotes health.

The best sources of prebiotic fiber are resistant starches such as unripened bananas and certain flours (not conventional wheat or white flour). The foods with the highest concentration of FOS prebiotic fiber are chicory root (an excellent substitute for those wishing to wean off of coffee), Jerusalem artichokes (which are nothing like regular artichokes; they more resemble ginger root), garlic and onions (especially raw).

According to another report by Statista, the value of the inulin (FOS) prebiotics ingredient market worldwide is expected to exceed $3 billion by 2025. Inulin has a natural slightly-sweet taste, which is the reason why FOS supplements are often used as a sugar substitute. Blue agave syrup (nectar) contains natural inulin.

When beneficial bacteria digest prebiotic fiber, chemicals called short-chain fatty acids are created. And this brings us to the next critical component of gut health…

Postbiotics: The End Result of Prebiotics + Probiotics

Short-chain fatty acids are the metabolic byproducts of probiotics eating prebiotic fiber. Researchers believe short-chain fatty acids improve neurotransmitter activity and communication as well as brain function, either directly or indirectly. These short-chain fatty acids are postbiotics, the end product of prebiotic fiber fertilizing friendly bacteria in the gut.

Postbiotic supplements are not as well-known as probiotics, but they do exist. There are a few primary short-chain fatty acids, the most popular being butyrate. Clarified butter, or ghee, is an excellent source of butyrate, and is well-tolerated by those who have trouble consuming fiber-rich foods. A comprehensive stool test, which can be ordered by a doctor, can analyze the level of postbiotics in your colon. If a stool test reveals low levels of short-chain fatty acids, supplements may be recommended to increase postbiotic activity.

But rather than rely on supplements to improve gut health, start consuming a diet rich in low-starch, high-fiber vegetables. Apples contain the fiber, pectin, which is one of the best sources of prebiotic fiber. As the saying goes, “an apple a day just may keep the doctor away.”