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Effects of Lemon Beverages on Bone Metabolism and Bone Mineral Density in Postmenopausal Women

Osteoporosis and the subsequent risk of bone fracture are characterized by enhanced bone fragility, resulting in an increased risk of fracture, and it is usually defined as a reduction in bone mineral density (BMD). These disorders account for a significant burden of morbidity and mortality worldwide and have become a major public health problem.

In women with postmenopausal osteoporosis, estrogen deficiency enhances the sensitivity to parathyroid hormone (PTH), leading to an increase in bone resorption. This results in elevated concentrations of calcium (Ca) in the blood. High blood Ca levels then prevent the release of parathyroid hormone (PTH), and, this, in turn, suppresses the production of 1,25-(OH)2 D3, which can promote Ca absorption in the intestine. Ultimately, the reduced absorption of Ca causes a decrease in bone mineral density (BMD). So it is critical to maintain blood Ca levels in the normal range.

Citric acid is mainly responsible for the acidic flavor of lemons. Recent studies have demonstrated that this organic acid acts as a chelating agent and promotes the absorption of minerals such as Ca and iron. 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 conclusion, in postmenopausal women, continuous consumption of Ca-supplemented lemon beverages improved Ca absorption and inhibited bone resorption. The suppression of bone resorption likely blocked bone formation mediated by the proliferation and differentiation of osteoblasts, resulting in the attenuation of high-turnover bone metabolism. The present results also suggest that citric acid in lemons enhances the absorption of dietary Ca. It’s expected that such beverages will have an efficacy in preventing osteoporosis in the future.


Article by Hiromi Ikeda, et al, from Japan.

Full access: http://mrw.so/4quGds

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