Going buggy with probiotics and prebiotics

April 9, 2008

YogurtWith all the ads hyping foods with pre- and probiotics bombarding consumers these days, one has to wonder how our bodies functioned before we knew about this facet of nutrition science. From cheese to yogurt to bread and refrigerated snack bars, probiotics and prebiotics are being added to food products at unprecedented levels. In fact, one source I consulted noted that spending on probiotic supplements nearly tripled from 1994 to 2003 in the USA.

My family doctor and I often chat about health and nutrition trends when I go to visit her. When I popped in for a check-up last week she and I agreed that there really isn’t sufficient science to justify the frenzy to include more of these substances in our diet.

In fact, according to Volume 49, issue 1267 of The Medical Letter, a newsletter designed to keep physicians up to date on topical health subjects, there’s woefully little study to support the perceived widespread need to eat foods that contain or sustain probiotic bacteria. And, of the studies that do exist, results are somewhat ambivalent.

What can you believe? Here’s what I learned after doing a little sleuthing:

Probiotics:
1. Probitiotics are live micro-organisms similar to those naturally found in people’s digestive tracts. These micro-organisms can be either bacteria or yeasts.
2. Examples of foods naturally containing probiotics are yogurt, fermented and unfermented milk, miso, tempeh, some juices and soy beverages.
3. It’s true that these micro-organisms are important. In fact, friendly bacteria are vital to proper development of the immune system, to protect against other microorganisms that could cause disease and to the digestion and absorption of food and nutrients. What is less certain is how often our natural supply needs to be replenished with additional food or supplement sources.
4. The quality and quantity of probiotics in most commercially sold foods and supplements is uncertain. In one study of 18 commercial probiotic preparations, 39% had discrepancies between the stated and actual concentrations.
5. Although the adverse affects of probiotics seem to be very few for healthy people, they have caused serious infections in people with suppressed immune systems or critical illnesses.

Prebiotics
1. Prebiotics are non-digestible carbohydrates that help the growth of desirable microflora in the large bowel. In other words, prebiotics are the food that the probiotic micro organisms in your digestive system need to flourish.
2. Eating too many prebiotics can lead to gas, cramping, bloating, and intestinal discomfort because the heavy gas producing bacteria that also hang out in your intestines also feed on prebiotics.
3. Foods that contain naturally occurring prebiotics are asparagus, beans, rye bread, honey, garlic, onions, pears, apples, most berries, barley, tomatoes and bananas.