It has become a common problem in the health industry to take a poorly researched concept and blow out of proportion its potential in the interest of capitalism. Probiotics are no exception. The actual research into probiotics has been limited and in some cases poorly designed, and the results have been misinterpreted, over-generalized and misrepresented by the supplement industry. So is there a use for probiotics or not?

Probiotics should be operationally defined up front. A probiotic can be generally defined as an “organism that contributes to the health and balance of the intestinal tract; also referred to as the ‘friendly,’ ‘beneficial,’ or ‘good’ bacteria, which when ingested acts to maintain a healthy intestinal tract and helps fight illness and disease.” According to researchers, a probiotic is specifically defined as “a viable microbial dietary supplement that beneficially affects the host through its effects in the intestinal tract.” When discussed in this article, we will be using the first definition, because we are including both supplements and dietary sources in our discussion.

This issue first came to my attention when I received a “newsletter” from a popular nutritional supplement store in my area. The headline read: “Proven benefits for probiotics.” The source was already suspect, being that the store sold probiotic products and stood to gain from such claims. The short article stated that 49 studies had investigated probiotics for “the prevention or treatment of diarrhea, cancer, lowering cholesterol levels and immune enhancement.” The phrasing throughout the article caused me to ask questions, and so I did. There was a small notation at the end of the article, for an article published in the American Journal of Clinical Nutrition. I decided to read the research myself.

As it turned out, the article cited was a meta-analysis of 10 years of research intro probiotics. As suspected, the claims made by my nutrition store’s article misrepresented the findings of the meta study. While they claimed probiotics “reduced the length of diarrhea infections,” the actual research only demonstrated this with rotavirus infection and no other kind of diarrhea, or diarrheal infections, of which there are many. Furthermore, the study specifically said, ” Consumption of foods containing Lactobacillus GG may shorten the course of rotavirus infection.” This should not be interpreted to mean that pill-form supplements of Lactobacillus GG, such as what would be available at this nutrition store, are the same thing as eating foods that contain it!

Edition of The Lancet featured an article that objectively summarized the medical community’s knowledge of probiotics, and the contrasting use/abuse of such knowledge by the health and fitness industry. The Lancet’s article was inspired by the release of a “probiotic multivitamin” in the UK in September of that year.

A Canadian probiotics researcher, Gregor Reid, was quoted in the article as saying that the British product “epitomizes what is wrong with the commercialization of probiotics”. A New Zealand researcher, Gerald Tannock, added: “Probiotics have been reduced to a very naive and simplistic level in order to market products”.

The article goes on to point out that there are simply not enough properly designed human studies to warrant the kind of claims being made about probiotics and the ensuing commercialism. Animal-based studies have demonstrated the importance of endogenous bacteria (i.e., those originating from the body), but the health effects of giving already healthy people exogenous bacteria (i.e., those that did not originate in the body) has not been proven. In other words, taking probiotics with your multivitamin as a preventive health measure is thus far totally without scientific grounds. Unjustified leaps in logic have been made from the research to the practice.

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