What are prebiotics: Prebiotics vs Probiotics – Part 1

Prebiotics and probiotics are confusing to people. How do I know if I have a prebiotic or a probiotic? What does each one have to offer? We’ll have two posts that will help to define prebiotics and probiotics, explain what they are, and how they can work together. This first post covers prebiotics, with an “E”.

Pebiotics vs probiotics So, what are these?

Also referred to as “prebiotic fiber,” are non-digestible fibers that act as a food source for some of the bacteria that naturally live in our gastrointestinal (GI) tract. You can think of prebiotics as fertilizer for “good” or beneficial gut bacteria. Examples of prebiotics that you may see on food labels include inulin, fructooligosaccharides (FOS) and polyols, including lactulose (1).

Types of fibers that are prebiotics can also be found naturally in many foods including human breast milk, whole grains, bananas, garlic, onions, artichokes and honey. This list is not all-inclusive, but gives you an idea of what foods contain prebiotics. Of note, it is ok to cook foods that contain prebiotic-type fibers without losing many of the benefits.

While everyday foods – fruits, vegetables, whole grains, nuts and seeds – contain fiber, we tend to think of these as specific fiber ingredients that are isolated and added to foods or formula for benefits. Many different everyday foods now have prebiotics added, and some nutritional formulas have prebiotics added. Prebiotics can also be taken as a supplement to the diet, for example a powder that you stir into foods or beverages.

How do you define prebiotics?

While all prebiotics act like fibers, not all fibers are prebiotics. Here is a list of characteristics that have been used to define them: (2)

  1. a non-digestible food ingredient (meaning that our digestive enzymes can’t break it down)
  2. that beneficially affects the host (that’s us!)
  3. by selectively stimulating the growth and/or activity of one or more of a limited number of bacteria in the colon that can improve the host health

So, in essence, a prebiotic is something that we add to food or nutritional formula for the benefits it offers. The benefits come from the fact that only certain “good” gut bacteria digest the prebiotic, meaning that they grow and thrive while other less-helpful bacteria may be crowded out.

Why would clinicians recommend prebiotics? How can they be helpful?

While prebiotics are mostly different fibers, not all fiber is the same. Various of these have been shown to have a variety of health benefits (3,4). Prebiotics may help to support total gut health. Some studies have also shown that some may help with nutrient absorption. And some can help to support growth of “good” gut bacteria if those levels are low for some reason.

Since most can be found in small amounts as part of the fiber in the foods we eat, you are probably already getting prebiotics in your diet. So, if you’re eating whole grains, fruits and veggies, you’re already getting the benefits of prebiotics, and then some!

Doctors and dietitians might recommend prebiotics for people who have low amounts of fiber in their diet, or might be looking for specific benefits. The best thing to do if you have questions about the possible benefits of prebiotics is to talk to your healthcare team. They can help you to understand the possible benefits of adding prebiotics to your diet, and may be able to help you choose the best source or type.

Why are these in some nutritional formulas?

For breast-fed infants, breast milk naturally contains molecules – human milk oligosaccharides (HMOs) – that behave like prebiotics. They are essentially a form of fiber that supports certain types of bacteria, bifidobacteria. The use of HMOs in breastfeeding infants registers Multiple health benefits. The prebiotics added to various infant formulas are:

  • Short-chain fructooligosaccharides (scFOS, a.k.a. fructooligosaccharides)
  • Long-chain fructooligosaccharides (lcFOS, a.k.a. inulin)
  • Galactooligosaccharides (GOS)
  • Polydextrose (PDX)

The diets of typical toddlers, children, and teenagers contain foods that are sources of fiber.

Fiber decreases when the infant has a diet supplemented by formula or is entirely dependant on formula.  Choosing a formula with added prebiotics can make up for some of the lower fiber in the diet. The prebiotics added to various nutritional formulas for children include:

  • scFOS
  • lcFOS
  • resistant starch
  • pectin

In the Neocate family of products, Neocate Syneo Infant (for infants) and Neocate Junior (for children) are the two formulas that are supplemented with prebiotic fiber. Both formulas contain scFOS and lcFOS, but in different amounts and ratios. Prebiotic fiber affects stool color, consistency and frequency: formulas without fiber are linked with green stools with a pasty consistency.

Now that you’ve learned more, check out the second post in this two-part series about probiotics, with an “O”!
What questions do you have?


Ellen Sviland-Avery joined the Nutricia team in 2014 and has been a registered dietitian for more than 12 years. She has extensive experience in pediatrics, metabolics and tube feeding. Prior to coming to Nutricia, she worked in home infusion. Her passion in pediatric nutrition started when she was in Birmingham working with children with neurodevelopmental disabilities and has continued throughout her career.

1. Slavin J. Nutrients. 2013;5(4):1417-1435.
2. Gibson GR. J Nutr. 1999;129(7 Suppl):1438S-41S.
3. Saavedra JM, et al. Br J Nutr. 2002;87S2:S241.
4. Waligora-Dupriet AJ, et al. Int J Food Microbiol. 2007;113:108.

Published: 12/20/2016
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