Could I become dependent on probiotics?

Conditions Expert Dr. Otis Brawley Chief Medical Officer,
American Cancer Society

Expert answer

You ask a fascinating question about an emerging area of medicine. The intestinal tract is host to a number of microbes, mostly bacteria that are needed for good health. Changes in the population of bacteria, such as removal of some of the good bacteria or replacement with some bad bacteria, can lead to a variety of health problems, especially inflammation of the bowel, diarrhea and pain. Interest in this area came first from the alternative medicine community, but interest and systematic investigative research into it has grown in conventional medicine.

The common principle is there are good bacteria and bad bacteria in the bowel. Some good bacteria are absolutely necessary for overall health and not just bowel health. In normal good health, some bad bacteria that cause disease are crowded out by good bacteria.

We can alter the balance of good to bad bacteria through taking antibiotics, which are intended, of course, to fight an infection by killing bad bacteria somewhere in the body; and the good bacteria in the bowel are killed as innocent bystanders. We can also ingest tainted food and get introduction of a high number of bad bacteria that cause an infection.

Physicians do sometimes manipulate intestinal microflora with a therapeutic intention. Intestinal bacteria can be altered in three ways. Through the administration of:

1. common antibiotics, which kill microbes (the good and the bad die);

2. prebiotics, which are things that promote the growth of good bacteria;

3. probiotics, which are beneficial bacteria.

These three methods are oftentimes combined in what is called symbiotic therapy.

The widest experience that most have in this area has been in the treatment of traveler's diarrhea, antibiotic-associated diarrhea and the inflammatory bowel diseases (ulcerative colitis, Crohn's disease). Clinical studies do suggest the importance of bacterial flora in other conditions that include lactose intolerance, atopic dermatitis and some other immune-mediated, rheumatologic and allergic diseases. This story is unfinished.

I believe taking moderate amounts of probiotics can be a good thing. Simply adding live cultured yogurt to one's diet, several times a week, is the most common and safest way to do this. Do not forget that a good diet includes at least five to nine servings of fruits and/or vegetables per day. This roughage is important in prevention of constipation and may be beneficial in preventing colon cancer and diverticulosis, the development of small pouches off the intestine.

While concern for bowel flora is important to health, enthusiasm and use of expensive probiotics has outpaced the scientific evidence. Most studies of probiotics are limited because they are small and short term. There are no long-term outcomes studies of probiotics other than those in normal foodstuffs. Also, considerable differences exist in composition, doses and biological activity of the commercial preparations available. The results with one preparation cannot be applied to other probiotic preparations or even to a different batch of the same preparation. Prebiotics can also be very expensive, and insurance does not reimburse for them.