High-sugar diet alters intestinal bacteria, making losing weight more difficult

"A report published in the new journal Science Translational Medicine has made an interesting discovery concerning the relationship between sugar intake and the balance of intestinal flora. Researchers have discovered that a diet high in sugar and fat substantially alters the bacterial composition in the gut, making it difficult to maintain a healthy weight.

Dr. Jeffrey Gordon of Washington University in St. Louis has been accumulating research for years that highlights the role intestinal bacteria plays in regulating bodily weight. Intestinal flora, sometimes called "good" bacteria, is vital for the proper digestion of food and assimilation of nutrients into the blood. When digestive bacteria is out of balance or otherwise altered, the body is unable to convert otherwise indigestible foods into digestible form.

The research, conducted on mice, experimented with implanting various strains of bacteria into mice in order to observe their effects. The two primary divisions of bacteria, Firmicutes and Bacteroidetes, compose approximately 90 percent of all bacteria. Studies by Dr. Gordon have revealed that Firmicutes bacteria are more efficient at digesting food that the body is unable to digest on its own.

With this in mind, Dr. Gordon decided to experiment with the various bacteria in gnotobiotic mice, or mice which had no bacteria in their intestines because they were raised in a sterile environment. What he found was that gnotobiotic mice who received bacteria from obese mice became obese as well. Similarly, those gnotobiotic mice who received lean-mice bacteria tended more towards leanness.

The same experiment was tried with human intestinal bacteria and similar results were achieved. What also became apparent was that mice who received bacteria from lean human intestines had a much higher proportion of Bacteroidetes than they did Firmicutes.

These mice, who began with a low-fat diet rich in healthy plants, were switched to a high-sugar, high-fat diet following the implant of the lean human bacteria. It was discovered that within 24 hours, the two phyla compositions switched resulting in the Firmicutes bacteria becoming more dominant than the Bacteroidetes bacteria."