If you've ever lost much of your so-called flora -- the various bacteria in your gut that help you process food -- I'll bet you never forget that experience. I'll spare you the details and just say that I'd go to tremendous lengths to avoid reliving it.
So should I be consuming the new breed of probiotic functional foods and dietary supplements? There's some evidence that says yes, though many questions remain unanswered, and some scientists claim we don't yet know which bugs to add to our diet.
Pasteurization has improved food safety by removing bad bugs from our food supply. But a healthy human gut contains a few pounds of good bugs (thousands of species and strains of bacteria). We know that things like antibiotics can disrupt flora for months. Now lots of products are being introduced into the market to help maintain or replenish it. However, it's not clear which products make a substantial difference for most people.
A gray area, evidence-wise? The World Health Organization defines probiotics as "live microorganisms that when administered in adequate amounts confer a health benefit on the host." WHO has issued guidelines on evaluating probiotics in food. The U.S. National Institutes of Health (NIH) National Center for Complementary and Alternative Medicine talks about the science behind probiotics, summarizing recent research and listing references.
This week's Aches & Claims column in the Wall Street Journal (behind paywall) details a few products backed by scientific evidence, identifying which bacteria they include and what benefits are associated with them. For example, the dietary supplement Florastor uses Saccharomyces boulardii yeast to help people avoid harmful effects from antibiotics. (However, in keeping with WSJ tradition, they don't name, or link to, the supporting studies. So if you want to see the evidence, you'll have to go looking on your own.) Other promising evidence was recently reported by Science Centric.
As explained in a 2008 L.A. Times article, most probiotics contain bacteria isolated from milk products, typically species of Lactobacillus or Bifidobacterium. The article mentions a clinical study of 135 patients published in the British Medical Journal that showed 22% improvement for people who had been taking antibiotics -- they drank a probiotic containing live Lactobacillus and Streptococcus. I'll award a few points to the Times for at least telling us what journal published the findings (even though they don't link to the article). In the BMJ I found a study concluding that, in a randomised double blind placebo controlled trial, people drinking a probiotic containing L casei, L bulgaricus, and S thermophilus experienced fewer negative effects. So, if I ever muster the courage to take antibiotics again, I'm washing the pills down with this stuff!
The jury is still out on much of this. Skepticism remains, however. Hundreds of new probiotic products are hitting store shelves, virtually all of them promising better digestion and/or overall health. And some of those claims are being challenged in court, including those for the Dannon product Activia.
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