Does Colon Cleansing for Treating Obesity Harm Beneficial Gut Bacteria?
Scientists have recently discovered that diet can determine the type of gut bacteria that resides in your digestive tract, which may have significant implications toward obesity, weight loss and a number of other disease conditions involving the intestinal tract. However, there are other implications that need to be addressed. In particular, what will the weight loss industry do with this information? For example, a popular trend in fighting weight gain advocated by celebrities is the contentious practice of colon cleansing. Reportedly, colon cleansing will detoxify the body’s digestive tract and cause weight loss. However, is this safe and what does it mean when beneficial gut bacteria—our natural flora—are flushed away and exchanged for a commercialized “dieting bacteria” product that is sure to come?
Scientists have known for a long time that the human digestive tract is home to hundreds if not thousands of different types of gut bacteria. Gut bacteria play an important role in digesting food and supplying the human body with nutrients that are absorbed through the intestine. In a recent study, scientists compared the bacterial flora from stool samples of volunteers who filled out a questionnaire about their dietary habits. What they found was that volunteers with diets rich in fatty foods had an abundance of one type of bacteria called “Bacteroides.” Volunteers whose diet was high in carbohydrates had an abundance of a different type of bacteria called “Prevotella.”
Extending their research further, the scientists did a 10-day study with two groups of subjects possessing the Bacteroide-type bacteria. A control group was fed the typical Bacteroide-preferred high-fat, low-fiber diet, whereas the test group was fed a Prevotella-preferred low-fat, high-fiber diet. The results were that although the levels of Bacteroide-type bacteria were lowered in the test group, it did not convert their gut bacteria type into primarily Prevotella-containing bacteria. The results suggest that switching bacterial types through diet may require gradual, long-term change.
The result of finding two differing diets with two differing gut bacteria types is not surprising. In an earlier study led by Paolo Lionetti, a pediatric gastroenterologist at Meyer Children Hospital in Florence, Italy, the gut bacteria in the fecal matter of children living in Africa was compared with the gut bacteria found in the fecal matter of children living in Italy. Italian children have a typical Western diet that is low in fiber, but high in animal protein, sugar, starch and fat. In comparison, the African children have a high-fiber, low-fat, vegetable-heavy diet. The results of the research showed that the Italian children had a predominant abundance of bacteria that is associated with people who tend to be obese, whereas the African children had a predominance of a bacterium that is associated with people who tend to be lean.
According to Lionetti, "The intestine is the site where the immune system meets the microbiota and we have demonstrated that diet is the most important thing for having a diverse, healthy gut." He also states that Western countries could benefit from changing their diets to better reflect those of people living in Africa. "If we change our diets, then we change our microbiota," he says. "Then we can improve our health."
Obesity and gut bacteria
The idea of gut bacteria playing a role in obesity is not a new one. In one study where gut bacteria from the intestine of an obese mouse was placed in the intestine of a normal-sized mouse, the normal sized mouse became obese. Based on this study, some have hypothesized that specific types of gut bacteria may be influencing the absorption of nutrients in the intestine of humans and thereby can also induce obesity. Currently there are no clear studies showing a direct causal relationship between bacteria type and nutrient uptake with obesity.
However, a lack of clear studies supporting a causal relationship has not stopped many companies that offer colon cleansing treatments from claiming that a relationship does exist. Typical claims from colon cleansing businesses include instant weight loss with a colon cleansing, detoxification of harmful bacteria and waste, replenishment of beneficial bacteria, etc. Some companies even go so far as to offer services that will flush you out and replace your bad bacteria with “probiotic super strains” of gut bacteria to rejuvenate your digestive tract. To accomplish these benefits, however, you have to be cleansed via a 60-liter flush of fluid. But is this what nature had in mind for our colon?
Our friend the colon
The colon is the large intestine part of the digestive system. It consists of the appendix, ascending colon, transverse colon, descending colon, sigmoid colon and the rectum. The function of the colon is to re-absorb digestive juices, water soluble salts and bile back into the blood stream and on to the liver. The colon is also a temporary storage site for undigested food and other bodily waste until elimination. It also acts as host for vast numbers of beneficial bacteria that help us with various tasks including immunity to infection, regulation of cholesterol levels, as well as production of a number of essential vitamins.
So, here we have a nice, evolutionarily-perfected waste disposal system that runs well on its own, but businesses try to convince us that we need a good pumping of up to 60 liters of fluid to remove old bacteria and replace it with their better bacteria—does this make sense? According to Glenn D. Braunstein, M.D. Chairman of the Department of Medicine at Cedars-Sinai Medical Center the answer is “No.” In an article published in the Huffington Post, Dr. Braunstein states, “The colon doesn't really need the assistance of irrigation. The bacteria that occur naturally in the digestive tract detoxify food, and the mucus membranes that line the colon prevent those discarded substances from reentering the blood and tissues. The colon also cleanses itself, shedding old cells about every three days so material doesn't build up. As is true for the "detox" diets, colonic cleansing for general health promotion is not supported by the published scientific literature, and does carry risks such as perforation of the colon or rectum, electrolyte imbalance and infection.”
So where does this leave us?
As of yet there is no scientific evidence demonstrating that replacing one type of bacteria with another in the human digestive tract can be harmful. Nor is there any evidence that doing so is efficacious either. Colon cleansing very likely does remove beneficial bacteria; however, there have been no reported cases of harm resulting due to a depletion of bacteria from this sort of treatment. Bacteria, if anything, are resilient, reproduce quickly and will re-establish itself in the gut. However, if nature teaches us anything it is that disrupting the environmental niches of an organism will often result in unforeseen consequences. Environmental changes must occur gradually so that organisms have time to adapt.
So, when the dieting industry comes to us with a new “science-based” weight-loss/bacteria-removing/colon-cleansing product (and I’m sure they will), just say “No” to the microbe and wait for the real science to work out the details—at least that’s my gut feeling about all this.
Linking Long-Term Dietary Patterns with Gut Microbial Enterotypes Published Online September 1 2011 Science DOI: 10.1126/science.1208344
The Journal of Family Practice August 2011 • Vol. 60, No. 08: 454-457 http://www.jfponline.com/
Impact of diet in shaping gut microbiota revealed by a comparative study in children from Europe and rural Africa; PNAS August 17, 2010 vol. 107 no. 33 14691-14696 http://www.pnas.org/content/107/33/14691