Prebiotic and Probiotic: confusing but critical

Philip J. Goscienski, M.D.

February 2010

Scientists don't make life easy for the rest of the folks. The terms in the title of this column are examples. They refer to two issues that have a profound influence on our health and have names that are confusingly similar.

The earliest humans survived mostly on plant foods that contain indigestible parts that we refer to as fiber. Bacteria that live within our intestines, the so-called normal flora, thrive on the material that our own digestive enzymes ignore. Nutritionists named the various types of fiber prebiotics and the bacteria that live on them within our large intestine probiotics. It helps to keep them straight if we think of E for Energy and O for Organisms. (Some authorities refer to the foods that contain these organisms as probiotics.)

Research scientists are trying to figure out how they work and industry is not far behind, finding ways to market them to the public.

This week we'll describe the overall concept of prebiotics and probiotics and in the following two weeks we'll discuss them separately.

This natural synergy (working together) between us and the bacteria that inhabit our large intestine makes it possible for both to survive and thrive. Synergy is common in nature. It's sometimes obvious, such as the relationship between flowering plants and the bees that pollinate them. Sometimes the mutual benefits are subtle, like the role that wildfires play in the survival of forests. Certain tree species need occasional fires to burst open their seed pods to allow a new generation to replace the oldest growth.

The partnership between humans and the bacteria that live within them began hundreds of thousands of years ago during which time our earliest ancestors became well adapted to the scores of plant species around them. The microbes that they swallowed along with food took up residence in their large intestine, where the undigested leftovers of plant foods gave the germs what they needed. The bacteria, in turn, released nutrients that had been trapped in the fiber and they provided benefits to their host. These included protection from disease-causing microbes, better absorption of nutrients such as calcium, lowering cholesterol and enhancing immunity.

The modern diet has disrupted this partnership. Hardly anyone eats the amount of fiber-rich plant foods that support our friendly bacteria. Antibiotic treatment often wipes out the ones that survive.

Philip J. Goscienski, M.D. is the author of Health Secrets of the Stone Age, Better Life Publishers 2005. Contact him at