Osteoporosis is a major worldwide health problem that affects 4-6 million women and 1-2 million men in the United States. Even more individuals have decreased bone mass, which, in addition to other risk factors, can be a major challenge to healthcare providers. Fractures, the most important consequence of osteoporosis, are associated with enormous costs and substantial morbidity and mortality. Those who experience an osteoporotic fracture are at increased risk for further fractures and frequently have a significantly reduced quality of life. The prevention and treatment of osteoporosis is thus of paramount importance.

The acid ash hypothesis proposed by Wachman and Bernstein (1968) put forth the paradigm that the net acid produced from the Western diet could contribute to the development of osteoporosis. Algorithms designed specifically to quantify the relative acidity of the diet have been developed. Those procedures are empirically derived relationships between nutrient analyses from food tables, the quantity of acid excreted in the urine, and estimated net endogenous acid production (NEAP). The underlying premise of the diet-based algorithms is that dietary intake serves to protect bone against excess metabolic acid production. In healthy individuals, the buffering of metabolic acid is under the control of the kidneys, lungs, and skeleton. In theory, when the diet is unable to provide sufficient buffering, calcium is withdrawn from the skeleton to maintain proper blood hydrogen ion concentrations, keeping serum pH between 7.35 and 7.45.

Research documenting the detrimental effects of a relatively acid-producing diet on bone mineral density (BMD) in free-living individuals has yielded small and not always statistically significant effects, causing some to question the effects of an acid-producing diet per se. However, the long-term studies of MacDonald, New, Fraser, Campbell, and Reid (2005) and New et al. (2004) support Wachman and Bernstein's assertion that 15% of skeletal calcium can be lost over a decade to buffer a mild metabolic acidosis resulting from dietary practices.

The research articles presented in this column look at a variety of approaches to the prevention and treatment of osteoporosis. The first article examines the role of dietary protein in bone health status as estimated by dual-energy x-ray absorptiometry in postmenopausal women in Illinois. The second article does a secondary analysis of a national database to explore the association between lead exposure and osteoporosis. The last two articles focus on the treatment and education of individuals with fractures and those who may or may not have osteoporosis.

REFERENCES