Artificial sweeteners are commonly touted as a healthy alternative to natural sugar. Sweeteners contain low to no calories (read about the types of sweeteners here), and they do not make blood sugars spike in diabetics.
However, a growing body of research lends a growing amount of concern to possible negative side to artificial sweetener use. 
A fascinating set of studies was collected and published recently in Nature, looking at how artificial sweeteners affect the bacteria in our intestines, and how these effects in turn may actually increase the risk of developing diabetes or pre-diabetes.  For the scientist with a couple of hours and a day with a good attention span may want to read the article for themselves – it’s heavy but super.  Here are the key results of their studies:
Both lean and obese mice who were fed artificial sweetener (saccharin, sucralose, or aspartame) were more likely to develop prediabetes compared to mice fed glucose or sucrose. (read more
about different types of sugar here).
They showed that the development of prediabetes in these mice was caused by a change in the types of bacteria in the mice’s intestines.  These altered bacteria are better at making calories from food accessible for absorption, meaning that mice (or humans) more readily absorb these calories, thereby contributing to higher blood sugars (and probably weight gain as well).
In humans, survey type studies have shown that people who use artificial sweeteners are more likely to be people with weight struggles and diabetes, but whether the artificial sweeteners cause these problems, or whether it is simply that people who have these problems are more likely to consume artificial sweeteners to help fix these problems, is difficult to separate. The authors therefore looked at a very small group of seven study participants who didn’t normally consume artificial sweeteners, and they found that when they ate artificial sweeteners for a week, four of the seven participants developed an increase in their blood sugars by the end of the week.  An examination of these people’s stools (oh yes they did) showed a marked change in the bacteria growing in their intestines after a week of artificial sweeteners. When they transplanted the stool of the people who developed higher blood sugars into mice (oh yes they did), the mice then went on to develop higher blood sugars as well.
So, in summary, these elegant studies suggest that artificial sweeteners may change the types of bacteria that grow in our gut, to types of bacteria that cause us to absorb more calories from food into our bloodstream, with the increase in sugar absorption increasing the risk of diabetes.  
So what is the best solution?  Eating added natural sugar undoubtedly increases our risk of diabetes, obesity, and metabolic syndrome, and there is now emerging evidence to suggest that artificial sweeteners may not be good for our metabolism either.

The best answer is to avoid adding added sweetener period, be it sugar or artificial sweeteners. 

Thanks to my friend and colleague, Pam, for the heads’ up on this article.

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