Musculoskeletal Benefits of Bicarbonate in Older Adults - A Dose-Finding Trial

With aging, men and women develop a mild and progressive metabolic acidosis. This occurs as a result of declining renal function and ingestion of acid-producing diets. There is extensive evidence that severe metabolic acidosis causes bone and muscle loss, but the impact of the chronic, mild acidosis on bone and muscle in older individuals has not been established. In a recent study, administration of a single dose of bicarbonate daily for 3 months significantly reduced urinary excretion of N-telopeptide (NTX), a marker of bone resorption and urinary nitrogen, a marker of muscle wasting and improved muscle performance in the women but not the men. These and other data support a potential role for bicarbonate as a means of reducing the musculoskeletal declines that lead to extensive morbidity and mortality in the elderly. Before proceeding to a long-term bicarbonate intervention study, however, it is important to identify the dose of bicarbonate most likely to be optimal and to characterize the subjects who benefit most from it. This double blind, placebo controlled, dose-finding study will evaluate the effects of placebo and two doses of bicarbonate on urinary NTX and nitrogen excretion and on lower extremity performance over a 3 month period in 138 men and 138 women, age 60 and older. Changes in urinary excretion of NTX and nitrogen and in selected measures of lower extremity performance will be compared across the three groups. The safety and tolerability of the interventions will also be evaluated. This investigation should provide needed information on the appropriate dosing regimen for men and women and on the study population that should be enrolled in a future bicarbonate intervention trial to assess the long-term effects of this simple, low cost intervention on important clinical outcomes including rates of loss in bone and muscle mass, falls, and fractures.