Probiotics and Prebiotics
~ November 1998 No.56 ~
Probiotics are an important part of the complex world of foods that are good for health. Probiotics are foods that contain live bacteria. It is the bacteria and metabolites which they produce that give these probiotics their health promoting properties. The best known example of a probiotic is yogurt. The experimental data for yogurt is still not as conclusive as one would like, but human studies related to the consumption of yogurt show increased milk digestibility, quicker recovery from certain types of diarrhea, enhanced immune function, reduction in certain cancers, and possible lowering of blood cholesterol levels.
The bacteria which are found in probiotic products such as yogurt, kefir and fermented vegetables usually aren't normally found in the human intestine. In fact, the intestinal environment is often a hostile one for these foreign bacteria. Because of this, bacteria eaten in probiotic products don't colonize the intestine but are flushed though and eliminated quickly from the body.
The bacteria that live in the intestines make up a very large and very diverse population. The numbers of each kind of bacteria change depending on age, diet, health status, and use of drugs and supplements. The bacteria that do thrive do so because they are able to adhere to the intestinal wall and use the semi-digested food that is passing through the intestines. It is not surprising to find that the bacterial population in the intestines of vegetarians is much different that that of meat eaters. Because some bacteria have specific nutrient requirements it has been proposed that adding these particular foods or nutrient to the diet could be a way of increasing the numbers of specific bacteria. That is what prebiotics are. Prebiotics are foods or nutrients that are used by specific bacteria and that can be added to the diet to increase the chances of these particular bacteria growing and thriving in the intestine.
Fructooligosaccharides (FOS) have been known as prebiotics for some time , but have been joined by galactooligosaccharides and other digestion resistant carbohydrates. FOS are compounds made up of fructose sugar molecules linked together in long chains. They can be found naturally in such foods as Jerusalem artichoke tubers, onions, leeks, some grains and honey.
People who have been eating their yogurt and therefore have a probiotic in their diet. Others have been eating foods that contain FOS and have had a prebiotic in their diet. Recently a yogurt has hit the market that contains both live bacteria and FOS. So now it is possible to eat a probiotic that contains a prebiotic. This should increase even more the beneficial effects of eating yogurt.
The concept of a prebiotic is one that could be included in many food products and it is likely that in the future we will be eating foods that are probiotics that also contain prebiotic ingredients. The more we learn about bacteria and how they affect our health, the more important probiotic products will become.
The Evidence to Support Health Claims for Probiotics The data to support label health claims for probiotic products are often difficult to provide.