Effects of Lemon Beverages on Bone Metabolism and Bone Mineral Density in Postmenopausal Women: A Double-Blind, Controlled Intervention Study with Ca-Supplemented and Unsupplemented Lemon Beverages

The aim of the present study was to elucidate how bone metabolism and bone mineral density are affected by the consumption of a lemon juice-containing calcium (Ca)-enriched beverage. The efficacy of this investigational product was evaluated in postmenopausal women during five months of continuous intake (intervention). This was a randomized, controlled trial. Eighty-three subjects were assigned to three groups. Using a double-blind format, the first two groups received a Ca-supplemented lemon-juice (lemon) beverage (LECA) or a Ca-unsupplemented lemon-juice (lemon) beverage (LE). The third group (control) received no intervention. Each subject in the LECA and LE groups consumed one bottle (290 mL) of their assigned investigational product every day for five consecutive months. After five months of intervention, the gain in bone mineral density at the lumbar spine was significantly larger in the LECA and LE groups than in the control group. In the femur, subjects in the LECA group gained significantly more bone mineral density than the control subjects. The largest gain in bone mineral density at the lumbar spine was observed in the LECA group. As for the concentrations of the bone resorption marker tartrate-resistant acid phosphatase 5b (TRACP-5b), subjects in the LECA group had significantly lower values than those in the control group. Similarly, when compared with the LE and control groups, a significant decrease was detected in the LECA group in the concentrations of the bone formation markers, bone alkaline phosphatase (BAP) and osteocalcin (OC). In postmenopausal women, continuous consumption of Ca-supplemented lemon beverages improved the absorption of Ca and inhibited bone resorption. This likely blocked the function of osteoblasts and led to the suppression of bone formation, resulting in the attenuation of high-turnover bone metabolism.