Update 3/2/13: The authors of the PLOS One have elaborated on their results showing a link between sugar intake and diabetes in a blog entry entitled: Interpreting our findings from today’s study on sugars and diabetes They write:

“The bottom line is that this is one of several studies from independent scientific groups that have questioned the old mantra that “a calorie is a calorie”. Some calories may be more metabolically harmful than others, and sugar calories appear to have remarkably potent properties that make us concerned about their long-term metabolic effects.”

Mark Bittman of the New York Times has a nice post today about the link between simple sugar consumption (in the form of sugary drinks, like sodas) and diabetes. A recent PLOS article by Basu and Lustig and colleagues shows a compelling epidemiological link between the amount of sugar eaten and diabetes. I remember learning in medical school that sugar does not cause diabetes. Now it turns out that that view is wrong. Others have postulated that eating high amounts of sugar is bad for us because of its effects on the microbiota, a point we also raised in our nutrient signaling paper. Like fats, carbohydrates have different effects on the composition of the microbiota. If anything, simple sugars have a greater growth promoting effect on pathogens and pathobionts than fats. Could it be that wen we doctors ask pre-diabetics to watch their sugar intake, we are really encouraging them to change their microbiota?

Kamada and colleagues in Science showed that microbes differ in their ability to metabolize sugars, with implications for growth on different diets:

This figure shows gene expression related to metabolism of different carbohydrate sources. (Science. 2012 June 8; 336(6086): 1325–1329.) MS stands for monosaccharide, which are simple sugars like fructose. PS stand for polysaccharides, like the complex carbohydrates in dietary fiber.  Some bugs, like E. coli, appear to be simple sugar specialists…. Does high fructose corn syrup in sugary sodas encourage the growth of harmful microbes in the gut?

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Joe Alcock

Emergency Physician, Educator, Researcher, interested in the microbiome, evolution, and medicine