Studies at the Moffitt Hospital, University of California at San Francisco, have shown that the metabolism of certain foods either raises or lowers the concentration of acid and base (alkaline) in the blood. Fruits and vegetables add the alkaline bicarbonate ion to the blood, thus lowering the blood's acid level, while meat, poultry and fish produce acid, thereby raising blood acidity.
The modern diet, high in animal protein, creates more acid than base in the body, resulting in a "net acid load." Until recently, scientists thought that this excess acid was safely excreted by the kidneys, resulting in no undesirable physiological consequences. However, research now indicates that acid can be retained in the body, and its presence is linked to osteoporosis, loss of muscle mass and reduction of hormone levels - all symptoms associated with aging. Declining kidney efficiency is common as people age, and contributes to the problem of acid buildup. Renal tubular failure may eventually result.
Researchers recommend that people modify their diets as they age to reduce the net acid loads. This means cutting down on animal foods. By putting more vegetables into their diets, people may reduce their chances of developing osteoporosis, kidney disease, and other age-related problems.
Considerable attention is now focused on the role of calcium in osteoporosis, but too much acid caused by high-protein diets may be the true villain. In one study, women whose net acid load was neutralized by alkaline supplements experienced increased retention of calcium and phosphorus, and greater new bone formation.
