Previous studies have shown an association between consumption of cola beverages and low blood calcium levels in children (Mazariegos-Ramos et al, J Pediatr, 1995;126:940-2) and bone fractures in adult women (Wyshak et al, Orthop Res, 1989;7:91-9).

We measured serum concentrations of calcium (Ca), phosphate (P), parathormone (PTH), serum markers of bone formation (osteocalcin, bone specific alkaline phosphate & carboxyterminal propeptide of type I procollagen) and urinary markers of bone resorption (pyridinoline/creatinine, deoxypyridinoline/creatinine & N-teleopeptides of type I collagen/creatinine) in 21 healthy females (mean age 17.9 ± 2.4 years) before, and at the end of a 2 week period of daily consumption of 1320 ml (4 cans) of either a phosphoric acid-containing cola beverage (Pepsi Max™, n=11), or a non-phosphoric acid-containing one (Diet 7-UP™, n=10). There were no significant differences in the Pepsi Max™ & Diet 7-UP™ groups with respect to age, body mass index, baseline concentrations of biochemical parameters and the daily intake of P (972 ± 361 & 1211 ± 377 grams, respectively) and Ca (729 ± 497 & 866 ± 382 grams, respectively).

There was a significant increase (p<0.05) in the mean serum concentration of osteocalcin in both the drink groups, but not in any of the other biochemical markers of bone formation or resorption.The mean serum concentration of PTH increased by 5.3% in the Pepsi Max™ group and 13% in the Diet 7-UP™ group (non-significant). As osteocalcin is synthesized only by osteoblasts, our results suggest that short term ingestion of cola and non-cola carbonated beverages stimulates bone formation in subjects with adequate intake of P & Ca. We speculate that this effect may be due to the anabolic effect of PTH on bone formation.