Diet Sodas and Non-Nutritive Sweeteners: It's All Bad
Diet sodas have been the subject of hundreds of studies in the last decade. The majority of those studies have found that diet soda is unhealthy, due to the artificial sweeteners it contains. For example, a 2009 study discovered that daily consumption of diet soda increased metabolic syndrome risk by 36%, and type 2 diabetes risk by 67%. Staggering numbers—and a reminder of the danger of diet soda.
In a study published in early 2016 in the journal Nutrition & Metabolism, a team of researchers at the NIH analyzed the effects of diet soda compared to other non-nutritive sweeteners. In addition to the two non-nutritive sweeteners tested (sucralose and acesulfame-potassium), diet soda also contains aspartame.
The study utilized 61 healthy adults: 30 adults consumed 355 mL of water with varying quantities of sucralose (0-250 mg), while 31 consumed 355 mL of caffeine-free diet soda and seltzer water with non-nutritive sweeteners. After drinking the beverages, the participants were subjected to oral glucose tolerance tests. The researchers collected blood samples over the course of 130 minutes, measuring glucose, insulin, GIP, GLP-1, glucose absorption, C-peptides, and gastric emptying. The participants also rated their levels of hunger and satiety.
The study discovered that the diet sodas increased GLP-1 (glucagon-like peptide), a hormone that causes the pancreas to secrete insulin in order to control rising glucose levels. However, the satiety levels remained unchanged, and the gastric emptying rate was consistent across all conditions. All participants showed an increase in insulin concentration, but with no visible changes in glycemia. The water/sucralose drinkers saw no change in any of the conditions.
The study proves that diet sodas are a lot more harmful than we once believed. While they were originally marketed as a "safe" and "healthy" alternative to regular high-sugar soda, this study (along with many others) proves that the sweeteners used in diet sodas can increase the risk of diabetes. Non-nutritive sweeteners can be almost as bad, so it's recommended to avoid them as well.
For those who want to be healthy, it's wise to eliminate soda from the diet completely. Unflavored quinine water/tonic water offers health benefits without the risk, but the addition of refined sugars and sweeteners can make the carbonated beverages a poor choice. In the end, regular water is always the best option.