What Are Prebiotics?

The standard definition for prebiotics from the International Scientific Association for Probiotics and Prebiotics is “a substrate that is selectively utilized by host microorganisms conferring a health benefit.” Simply stated, prebiotics are food for our good bacteria otherwise known as probiotics. They produce health benefits to the host when using prebiotic food.

Historically, the term “prebiotic” was introduced from studies on gut microbiota. Thus, for a long time, dietary fibers were the only substance regarded as prebiotics. Later, researchers revealed that microbes live in other interfaces between us and the outside world, including the airway, reproductive tract, and skin. However, probiotics in those environments feed on substrates other than dietary fiber.

The health benefit of prebiotics are a result of their usage by probiotics, and therefore are part of the function of the beneficial bacteria. I have summarized the probiotic functions in another blog. Briefly, the ones relevant to prebiotics include modulation of our immune system and the provision of extra energy and nutrients. The modulation of the immune system is the one that is ubiquitous in all interfacial microbial niches in human beings.

The different kinds of prebiotics

Prebiotics support modulation of the immune system in the gut, airway, reproductive tract, and on the skin. I have described the detailed mechanisms of how probiotics interact with our immune system in our research article. Please refer to the study for details. Briefly, probiotics utilize prebiotics to produce metabolites that calm down the immune system. The prebiotics for this function are listed in Table 1. 

Table 1. Prebiotics in microbial niches

GutAirwayVaginaSkin
PrebioticsDietary fibers: FOS, GOS, HMO…Sugars, amino acidsSugars
Natural sourcesFood: chicory root, dandelion greens, Jerusalem, artichoke, garlic, onions, asparagus, bananas, milkSaliva, mucusMucus
ProbioticsBifidobacterium, Lactobacillus, FaecalibacteriumStreptococcus & VeilonellaLactobacillus acidophilus
Best practices for healthy peopleEat food rich with dietary fibers, not only the ones above, but add whole grains, veggies, fruits, and fungi.Enough personalized oral hygiene to keep teeth and gums healthy, not excessive to suppress oral probiotics.Leave it alone.Not too many showers, use gentle cleaning agents, no antibacterial soap.

Do I need to take prebiotics regularly?

As you can see from table 1, prebiotics and probiotics are paired together naturally. Prebiotics usually exist in those niches in abundance for the proper probiotics to flourish. This means we do not have to pay special attention to them. Probiotics should thrive naturally and make peace with human hosts. Under normal conditions, a healthy diet with proper portions of fermented food should be sufficient for most people’s gut health. The other niches should take care of themselves as long as we do not interrupt them too much with excessive personal hygiene. Please see my other blog on probiotics for additional details.

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