Alkaline Diet: Does pH Affect Health and Wellness?
The trendiness of dietary acid and alkaline balance — along with diets that promote "alkaline" vegetables and fruits and discourage "acidic" meats, dairy and processed foods — has waxed and waned for decades. But what does dietary alkalinity mean? And is there enough evidence to support its use for overall health, and bone health in particular?
Confusion and interest about food's influence on acid-alkaline balance abound, due in part to popularity among celebrities and non-scientific health enthusiasts who tout versions of an "Alkaline Diet" as a cure-all for a wide range of maladies, from cancer to heart disease. While these types of claims typically are red flags within the health and medical community, as well they should be, there is some research backing health benefits of this eating pattern — making it worth clarifying what an alkaline eating pattern entails and the science surrounding this popular diet.
Before sifting through the evidence, two common points of confusion should be addressed: First, the acid-alkaline balance in question is not that of the blood. The pH of human blood is strictly maintained at about 7.4 (7.35 to 7.45). The lungs and kidneys spare nothing to keep the pH tightly controlled since the consequences of blood pH changes would be life-threatening. It's more about what the body has to do in order to keep the blood's pH where it needs to be. The basic premise of an alkaline diet is that what a person eats influences how much compensating the body has to do in response to that meal.
The second point is the concept of a food being "acidic" or "alkaline" in composition, on its own, versus its potential effect on the body. Lemon juice and tomatoes, for example, are acidic. But when ingested, they promote alkalinity. The pH of the actual food does not dictate the net effect on the body. Rather, it's the "potential renal acid load, " or PRAL, of a food — a value that measures acid excretion in the urine — that determines where it fits within the context of acid-alkaline balance.