By Ross Pelton, RPh, PhD, CCN
Several recent studies have reported how dietary sugar can cause or contribute to the development of dysbiosis and leaky gut or intestinal permeability. Dysbiosis is the term that refers to intestinal problems that are caused by an imbalance between good and bad bacteria in the GI tract.
Leaky gut or intestinal permeability is a condition that is caused by inflammation in the intestinal tract, which allows inappropriate contents from the intestinal tract to leak into circulation throughout the body. Inflammation in the intestinal tract is frequently caused by bad bacteria and leaky gut is now know be associated with the development of autoimmune disease and many other health problems.
In a recently published study in the Proceedings of the National Academy of Sciences, the authors report how excessive intake of dietary sugars can cause an overgrowth of harmful bacteria in the colon.
Normally, dietary sugar is absorbed in the upper intestinal tract, but this new research suggests that when excessive amounts of sugar are ingested, some of the sugar passes through the intestines unabsorbed. When sugar reaches your colon, it can inhibit the growth of beneficial bacteria and encourage the overgrowth of harmful bacteria.i
Specifically, this study reports that unabsorbed sugar in your colon can prevent the good bacteria from producing a key protein called Roc, which stands for Regulator of Colonization. Roc is required for growth of the healthful species Bacteroides thetaiotaomicron (B. theta) in your colon. Lean, healthy individuals have been found to have higher levels of the Roc protein. Although this research was done in mice, the authors suggest it should also apply to humans.
Results of another study explains how high dietary sugar can cause dysbiosis and impair gut barrier function, resulting in leaky gut.ii These effects were found for both fructose and glucose.
In a third study, it was shown that early-life consumption of sugar has a negative effect on the gut microbiome.iii These sugar-induced changes in the microbiome result in decreased numbers of beneficial Bacteroidetes bacteria which are known to support healthy immune function and prevent the overgrowth of harmful pathogens. At the same time, increased consumption of sugar early in life was shown to increase numbers of Proteobacteria and Firmicutes, which are associated with dysbiosis and obesity.
Many studies have reported that increased consumption of sugar increases risks to type 2 diabetes and obesity.iv The results of these studies add to the increasing body of scientific literature which reports an association between excessive consumption of dietary sugar and dysbiosis and other gut-related problems such as intestinal permeability or leaky gut.