diet-cola-kidneysAnother thing to add to the long list of things that diet cola isn't good for -- your kidneys. Women who drank more than two diet sodas a day showed a 30% decrease in kidney function, according to research presented at according to research presented at the annual meeting of the American Society of Nephrology. "This was true even after taking into account factors such as age, high blood pressure, diabetes, and physical activity," says Web MD.