Recent studies have found that well-meaning efforts to avoid the dangers of sugar can backfire. In fact, several common sugar substitutes: saccharin, sucralose, and aspartame, have been linked with glucose intolerance and weight gain.
How does this happen? Some 80% of the human immune system resides within the gut, in the form of the “microbiome,” the diverse colony of friendly and essential bacteria that accompany us throughout our lives. But if the microbiome is disturbed, it can become unhealthy, leading to autoimmune disorders and, apparently glucose intolerance.
Artificial sweeteners, especially saccharin, have been found to cause dysbiosis, or an unhealthy imbalance of gut bacteria. This, in turn, leads to glucose intolerance (a precursor of diabetes), as well as weight gain. This was found to be true not only in mice that were fed artificial sweeteners, but in mice that received bacterial transplants from the special-diet mice.
It also held true in humans. In a small study, more than half of the healthy human subjects who added artificial sweeteners to their diets developed glucose intolerance in less than a week. A larger-scale study of about 400 people found a correlation between metabolic syndrome (including glucose intolerance and weight gain) and consumption of artificial sweeteners.
In addition to this new research on the microbiome, there are reasons not to use certain artificial sweeteners dating back to the 1980s. Aspartame, for example, has been linked with some fairly serious neurological disorders.
Are there any “safe” sugar substitutes? To date, stevia has not been linked with dysbiosis, cancer, or neurological symptoms; and it does not raise blood sugar. People who are allergic to chrysanthemums are more likely to be allergic to stevia. It is relatively new to the market, so not all the evidence is in, but at this point it looks like one of the best bets if you must avoid sugar.
For further reading:
Abbott, A. (2014). Sugar substitutes linked to obesity: Artificial sweetener seems to change gut microbiome. Nature News. Posted September 17, 2014. http://www.nature.com/news/sugar-substitutes-linked-to-obesity-1.15938
Collins, F. (2014). Taking a New Look at Artificial Sweeteners. NIH Director’s Blog. Posted October 7, 2014. http://directorsblog.nih.gov/2014/10/07/taking-a-new-look-at-artificial-sweeteners/
Farley, A. (2013). Symptoms of Aspartame Poisoning. Livestrong.com. Posted August 16, 2013. http://www.livestrong.com/article/29349-symptoms-aspartame-poisoning/
Lalonde, B. (2013). Known Side Effects of Stevia. Livestrong.com. Posted October 21, 2013. http://www.livestrong.com/article/368454-known-side-effects-of-stevia/
Roberts, H.J. (1988). Reactions attributed to aspartame-containing products: 551 cases. Journal of Applied Nutrition, 40: 85-94, 1988. See summary of reactions here: http://www.fda.gov/ohrms/dockets/dailys/03/jan03/012203/02p-0317_emc-000199.txt
Suez, J., et al. (2014). Artificial sweeteners induce glucose intolerance by altering the gut microbiota. Nature 514, 181–186 (09 October 2014). doi:10.1038/nature13793.