Dear Mayo Clinic: I typically drink three or four cans of diet soda each day, and my doctor told me it may be the cause of my high blood pressure. But, I’ve been drinking this much soda for years and have never had any issues. Why would it suddenly affect my blood pressure?
It’s unlikely that the diet soda you drink is causing your high blood pressure. A number of studies have examined this topic, and there is no evidence to suggest a link between regularly drinking diet soda and an increase in blood pressure. In fact, some research findings seem to suggest the opposite. Diet soda actually may contribute to lowering blood pressure.
A variety of artificial sweeteners are available on the market. All of them are judged to be safe for general use. The three artificial sweeteners primarily used in soft drinks and diet sodas are stevia, sucralose and aspartame. Stevia, a natural product, has been shown to possibly lower blood pressure in people who have high blood pressure. Sucralose, which has almost the same molecular structure as table sugar, does not have much, if any, effect on blood pressure.
The bulk of diet sodas are made with aspartame. Aspartame does not appear to cause high blood pressure either. For example, in one study looking at a possible connection between the two, rats were fed either sugary foods or large doses of aspartame. The results showed that blood pressure went down in the group that consumed the artificial sweetener.