DEAR DR. BLONZ: Can you explain for me and your other readers the difference between probiotics and prebiotics? Are foods and supplements containing these things beneficial? -- B.S., Walnut Creek, California
DEAR B.S.: There is a diverse colony of "friendly" bacteria that reside in our intestines -- mostly in the large intestine, also referred to as the colon. The scientific term for this colony of benevolent bugs is the "human microbiome." Consider this: There are more organisms in each of our microbiomes than there are cells in our bodies.
While our understanding of how these bacteria all work together and influence our well-being is in its relative infancy, it is now widely appreciated that the microbiome plays an important role in our general health. It is a fascinating and evolving field. (For a more in-depth discussion, check out tinyurl.com/gnlwgvg).
Probiotics are dietary sources of the specific bacteria in the microbiome. These can be found in cultured foods, such as yogurt and kefir, or in dietary supplements that contain levels of individual strains of bacteria. Typical organisms include specific strains of Lactobacillus, Saccharomyces, Bifidobacterium and Streptococcus. While there are major and minor players, each of us has our own symphony of microorganisms based on our diet, lifestyle, health status, genetics and even the medications and dietary supplements we use.
It should be appreciated that the microbiome is a "Wild West" situation with no sheriff -- the only law is survival of the fittest. So, too, is the current state of scientific affairs regarding how we might be able to adjust flora to accomplish specific health goals.
The potential for interpersonal variability makes it difficult to predict the effect of a particular probiotic, or combination of probiotic organisms, on any given individual. Then there are issues of effective dose and persistence. How much is needed, and how long does it have to be administered, for there to be a lasting effect with a particular individual's microbiome?
At present, we find probiotics being marketed to the general population claiming to accomplish health benefits. As we continue to gather evidence, researchers will gain a better understanding of the potential for probiotics to influence the microbiome, and effect changes in our health. Prudent consideration is advised in the meantime. Stick with advice from trained experts; if specific health problems are on the table, consult with physicians familiar with your particular health situation.
A prebiotic is a food that facilitates the growth and survival of the probiotic bacteria. These tend to be substances that are not effectively broken down by the human digestive system, allowing them to pass through to the large intestine where they serve as food sources for the flora. Dietary fibers, inulin, and oligosaccharides are substances that serve as prebiotics. They tend to be found in vegetables, whole grains and legumes, so a plant-based diet rich in whole foods will have a ready supply of nourishment for the friendly flora in your system.
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