diets high in potassium, calcium and magnesium (all of which are cations) were presumed to be alkaline forming. Other investigations showed specific foods, such as cranberries, prunes and plums had unusual effects on urine pH. While these foods provided an alkaline ash in the laboratory, they contain a weak organic acid, hippuric acid, which caused the urine to become more acidic instead. Historical uses of alkaline diets Historically, the medical application of alkaline diets largely focused on preventing recurrence of kidney stones as well as the prevention of recurrent urinary tract infections, by relying on the recognized ability of such diets to affect urinary pH. Years ago, such a diet was used to adjust the acidity of the urinary environment that the stones formed in, and could hypothetically help prevent stones from forming or the development of UTIs. However, the analytical methods that attempted to calculate the effects of food on urinary pH were not precise except in very general terms, making effective use of such diets difficult. Therefore, medications, which can more reliably alter the urine pH, rather than diet modification, have been the treatment of choice when trying to alter urine pH. While there have been recent improvements in recognizing different variables that can affect acid excretion in the urine, the level of detail needed to predict the urinary pH based on diet is still daunting. Precise calculations require very detailed knowledge of the nutritional components of every meal as well as the rate of absorption of nutrients, which can vary substantially from individual to individual, making effective estimation of urine pH not currently feasible. See also List of ineffective cancer treatments D. C. Jarvis – Advocated higher blood acidity as prevention and treatment Hay diet List of diets References External links About alkaline diets on ScienceBlogs Acid–base physiology Alternative medical treatments Fad diets