probiotics and prebiotics paper

All right, at the very great risk of looking excessively lazy, here’s what I did while offline. Pretty much all I did in the way of homework. Pretty painful. Wrote it over a single very long night and into the next day, missing half of the next day’s classes but attending, stupidly enough, PE because that’s where attendance counts most and nearly falling a whole bunch of times trying and failing to learn a new roundhouse kick… Oh, let’s just get it over with. Here you go.

Paper #2 for class on Food Science, Review of Probiotics/Prebiotics articles

Amy Brown defines probiotics in her textbook Understanding Food: Principles and Preparation as “live microbial food ingredients (i.e., bacteria) that have a beneficial effect on human health” (Brown 2011, G-6) In middle-class America, the idea of voluntarily consuming bacteria is counter-intuitive. We spend a great deal of time and money trying to find new ways to kill bacteria in our food supplies before they reach us. We take antibiotics for serious diseases. We pasteurize cheese and beer; killing most of the microorganisms that make these products to reduce our chances of ingesting toxic bacteria. We are even trained to fuss at children for eating off our “germy” home floors. We refuse to eat any but the freshest restaurant produce. Yet we are also quite prone to fads.

Researchers and salesmen have proposed many reasons for us to indulge in the recurring fad of probiotics. The most common claim is that products alleviate undesirable gastrointestinal symptoms such as bloating, irregularity, gas, stomach discomfort, and diarrhea (Schardt 2006, 7-9). Yogurt in particular has been used in diarrhea patients for centuries (Brown 2011, 222). Preliminary research seems to show that some probiotics can shorten the duration of colds and help balance a digestive system upset by hospital- or antibiotic-induced infections (Schardt 2006, 8-9 under Stonyfield Farm Yogurt and Florastor).  Also, probiotics are classified as food and thus seem to have fewer risks and gentler regulations than medicines like antibiotics.

Consuming live bacteria is certainly not without risk, though. Some challenges to the probiotic industry include reducing risk of gastrointestinal upset possibly caused by the bacteria themselves (Schardt 2006, 8 under DanActive Drink) and preventing contamination by wild bacteria and early spoilage. Various strains of bacteria may cause allergic reactions. Testing is difficult and expensive and relies on volunteers, which introduces a high probability of bias. As the term “probiotic” is not tightly regulated, confusion can easily result as to what exactly a product contains. Some manufacturers make claims bordering on panacea for poorly tested products (Schardt 2006, 9 under Culturelle). All of this can be dangerous to the unwary consumer.

Another consideration to remember is that researchers are just beginning to look into what causes a change in human gut microflora. A strong contender for the post is diet (Wu et al. 2011, 1-5); others might include genetics and cultural or geographical environment. One study connected all three in a study of how the gut may influence obesity and vice versa (Flier and Mekalanos 2009, 1-3). Probiotics introduce new bacteria into the gut (though not in large amounts) and thus could theoretically have a direct influence on the composition of the gut microbiome. Yet long-term studies should be performed, especially on the effect of multiplying “good” bacteria to crowd out and place a barrier between the body’s immune system and “bad” bacteria. There is so much bacteria in the human gut that it will take researchers some time to find out whether some bacteria are more important than others in disease prevention and control (Wu et al. 2011, 3).

Probiotics have a mixed reliability rate; sometimes there is research to support health claims blazoned on packaging, but sometimes the evidence is elusive. Before deciding to incorporate any product containing probiotics into their diet, consumers ought to check any scientific studies performed on the specific strain of bacteria for success rate as proof of packaging claims. For example, in an article summarizing this information for several products on the market in 2006, some probiotics were in a far more advanced stage of testing than others: the bacteria in Kashi Vive Cereal had never even been tested for health benefits, while the yeast in Florastor reduced incidence of diarrhea after a course of antibiotics in several large, well-done studies (Schardt 2006, 8-9). For further contrast, the DanActive Drink was only studied in a small population of elderly men and women in Italy, and a fourth of the study’s participants suffered from such intense gastrointestinal problems while using the drink that their daily dose was halved (Schardt 2006, 8). Thus, unless a consumer takes the time to research any probiotic health claims himself, he could end up paying top dollar for a product that is untested and may even be harmful.

According to its website, the National Yogurt Association’s “Live Active Culture Seal” is an official seal voluntarily placed on yogurt products that contain a certain quota of live bacteria. Because this seal is voluntary and counts both starter bacteria used to ferment the yogurt and added probiotics, naturally high levels of starter bacteria can make the designation somewhat misleading (Douglas 2008, 514).

According to the Brown textbook, prebiotics are “Nondigestible food ingredients…that support the growth of probiotics” (Brown 2011, G-7). Mostly, prebiotics are fibers that pass through the stomach undigested and become food for gut bacteria, which can react to provide mutual benefit or to attack their host. Prebiotics thus may also influence the bacterial population of the human gut.

Considering that research into the benefits of probiotics is inconclusive and I am generally healthy and broke, I would not change my own diet to incorporate this new food trend. Nor (in the logical tradition of “if it ain’t broke don’t fix it”) would I recommend specialized probiotics to other healthy friends. According to a microbiologist who wrote a book on the subject, the only reasons for a healthy person to take probiotics are if he is about to take antibiotics, go to the hospital, or travel outside of the country (Schardt 2006, 7). A case might be made for their use in an ill person who is suffering from a specific condition that a specific strain of bacteria is scientifically proven to alleviate. However, specialized probiotics are too new, expensive and unproven to recommend to the average person. Yogurt would be a safer choice for anyone wishing to follow the newest diet trends.

Reference List

Brown, Amy. 2011. Understanding Food: Principles and Preparation. 4th ed. Belmont: Wadsworth, Cengage Learning.

Douglas, Linda C., PhD, RD. and Mary E. Sanders, PhD. 2008. Perspectives in Practice: Probiotics and Prebiotics in Dietetics Practice. Journal of the American Dietetic Association 108, no. 3 (March): 510-521.

Flier, Jeffrey S. and John J. Mekalanos. 2009. Gut Check: Testing a Role for the Intestinal Microbiome in Human Obesity. Science Translational Medicine 1 no. 6 6ps7 (November 11): 1-3.

National Yogurt Association. (accessed October 14, 2011).

Schardt, David. 2006. Helpful Bacteria: Should you take probiotics? Nutrition Action Healthletter (December): 7-9.

Wu, Gary D., Jun Chen, Christian Hoffmann, Kyle Bittinger, Ying-Yu Chen, Sue A. Keilbaugh, Meenakshi Bewtra, Dan Knights, William A. Walters, Rob Knight, Rohini Sinha, Erin Gilroy, Kernika Gupta, Robert Baldassano, Lisa Nessel, Hongzhe Li, Frederic D. Bushman, and James D. Lewis. 2011. Sciencexpress Report: Linking Long-Term Dietary Patterns with Gut Microbial Enterotypes. Science 334 no. 6052 (September 1, 2011): 1-4. 10.1126/science.1208344 (downloaded September 25, 2011).


I’ve never thought of the gut as a “microbiome.” But according to one of the newest nutrition trends, a change in what we eat influences what kinds of bacteria grow in our digestive system. Since we have a symbiotic relationship with those bacteria (the reasoning goes), changing the types of colonies we encourage and discourage might change just about everything about how we feel and which diseases we get. In a study published last month (full reference in previous post, short: Linking Long-Term Dietary Patterns with Gut Microbial Enterotypes, Wu et al) researchers found an association between diets focused on vegetables or meats and different taxa of bacteria. Though these associations aren’t strong enough to control or even explain every part of our gut bacterial composition, they may play a role in why we high-animal protein/fat Westerners get different diseases than people who eat more carbs and less meat. Pretty neat, huh? The human body is such an intricate mystery.

citation styles

I’m experimenting with NoodleBib tonight. It’s working, but oddly. Some things just don’t seem to do as well as others.

Douglas, L. C., PhD, RD., & Sanders, M. E., PhD. (2008, March). Probiotics and
Prebiotics in Dietetics Practice. Journal of the AMERICAN DIETETIC 
ASSOCIATION, 108(3), 510-521.

Flier, J. S., & Mekalanos, J. J. (2009). Gut Check: Testing a Role for the
Intestinal Microbiome in Human Obesity. Science Translational Medicine, 
1(6), 6ps7.

Wu, G. & Lewis, J. Science 334 no. 6052 (2011); Published online September 1, 2011 (10.1126/science.1208344).

Schardt, D. (2006, December). Helpful Bacteria: Should you take probiotics?
Nutrition Action Healthletter, 7-9.