The high animal protein, high grain diets of Western nations are of significance to health because they produce diet-induced metabolic acidosis. This is because animal proteins and grains are metabolised to acidic compounds which decreases the pH of the blood. These acid conditions are further compounded by the low potassium intakes in most modern Western diets. The result is a mobilisation of minerals (calcium, phosphate and carbonate) from bone in an attempt to neutralise the acidic plasma, and an increase in the excretion rate of calcium in the urine (hypercaliuria). One theory suggests that the decrease in bone formation and increase in bone resporption may result from osteoblastic prostaglandin E2 synthesis via the action of phospholipase A2 on arachidonic acid in cell membranes and stimulation of the RANK / RANKL signalling pathway. Over a lifetime this mild metabolic acidosis could have profound effects on bone health.
To investigate the effects of neutralising acidic western diets, researchers1 fed 161 postmenopausal women with low bone mass oral potassium citrate (treatment) or potassium chloride (control) daily in a double-blind study. Alkali salts such as potassium citrate are thought to be able to neutralise the diet-induced acid load and may decrease calcium excretion and therefore increase calcium retention. Those supplemented with potassium citrate displayed increased bone mineral density at vertebrae L4 to L2, at the femoral neck and total hip at 12 months, but effects were seen in as little as 3 months. Those in the potassium chloride group showed deterioration in bone mineral density. The potassium citrate group also displayed a reduced calcium excretion, as well as an increase in citrate excretion indicative of sustained systemic alkalisation. In both groups there was a significant reduction in blood pressure, probably due to the potassium.
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