Eating a diet high in protein and cereal grains leads to elevated amounts of acid in the body which can increase calcium excretion and thus weaken bones, say researchers from the Human Nutrition Research Center on Aging at Tufts University.

As we get older our bodies are less able to excrete the acid that is produced during protein metabolism. This results in the body trying to correct the acid/base balance, and it does this by a process known as bone resorption, where the body breaks down bones to release minerals such as calcium, phosphates, and alkaline salts into the blood. However, this weakens bones and leaves people susceptible to fracture.

Bess Dawson-Hughes, M.D., and colleagues conducted a study of 171 men and women aged 50 and over to see if increasing the alkali content of the diet would provide a solution to this problem. Participants were randomly assigned to receive placebo or potassium bicarbonate, sodium bicarbonate, or potassium chloride for three months. All participants also received calcium and vitamin D3 daily. Results showed that participants who received bicarbonate  had significant reductions in urinary N-telopeptide and calcium excretion, thus suggesting that bicarbonate reduced bone resorption.

“In this study, we demonstrated that adding alkali in pill form reduced bone resorption and reduced the losses of calcium in the urine over a three month period,” said Dr. Dawson-Hughes. “This intervention warrants further investigation as a safe and well tolerated supplement to reduce bone loss and fracture risk in older men and women.”

Dawson-Hughes B, Harris SS, Palermo NJ, Castaneda-Sceppa C, Rasmussen HM, Dallal GE. Treatment with Potassium Bicarbonate Lowers Calcium Excretion and Bone Resorption in Older Men and Women. Journal of Clinical Endocrinology & Metabolism. Published onlince October 21st 2008. doi:10.1210/jc.2008-1662

News release: Calcium and Vitamin D May Not Be the Only Protection Against Bone Loss. Endocrine Society. December 1st 2008.