多吃水果蔬菜或可有效降低骨质疏松症的风险

  一篇发表在国际杂志Osteoporosis International上的研究论文中，来自萨里大学的研究人员发现，在水果和蔬菜中含量丰富的钾盐（碳酸氢盐和柠檬酸盐）在改善个体骨质健康上扮演着重要的角色；在骨质吸收过程中往往会发生骨质分解，而本研究首次揭示了钾盐可以减少骨质吸收，进而增加骨质强度。

  研究者Helen Lambert表示，高水平钾盐的摄入可以明显减少尿液中钙质和酸的排泄，这就意味着，过量的酸可以被中和从而使得骨质中的矿物质被保存下来。以高水平动物蛋白和谷蛋白为标志的典型西方饮食往往会引发机体中出现过量的酸，这往往会引发骨质弱化及骨折发生。

  本研究显示，钾盐可以有效抑制骨质疏松症，这正如研究者发现骨质吸收降低一样；尽管骨质吸收和骨质形成是一个自然过程，其可以促进骨骼生长、愈合及适应环境，但在骨质疏松症中，这种平衡往往会发生转移，从而出现骨质破损的情况大于骨质形成，最终引发骨质易碎及骨折。

  当前骨质疾病在英国影响着超过300万人的健康，在50岁以上的个体中，二分之一的女性及五分之一的男性都会因为较差的骨质健康常常发生骨折。本文研究结果表明，多吃水果和蔬菜或许是一种很好的改善个体骨质强度，预防骨质疏松症的方法。（转化医学网360zhyx.com）

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The effect of supplementation with alkaline potassium salts on bone metabolism: a meta-analysis
Osteoporosis International DOI:10.1007/s00198-014-3006-9
H. Lambert, L. Frassetto, J. B. Moore, D. Torgerson, R. Gannon, P. Burckhardt, S. Lanham-New
Summary
The role of acid–base metabolism in bone health is controversial. In this meta-analysis, potassium bicarbonate and potassium citrate lowered urinary calcium and acid excretion and reduced the excretion of the bone resorption marker NTX. These salts may thus be beneficial to bone health by conserving bone mineral.
Introduction
The role of acid–base homeostasis as a determinant of bone health and the contribution of supplemental alkali in promoting skeletal integrity remain a subject of debate. The objective of this study was, therefore, to conduct a meta-analysis to assess the effects of supplemental potassium bicarbonate (KHCO3) and potassium citrate (KCitr) on urinary calcium and acid excretion, markers of bone turnover and bone mineral density (BMD) and to compare their effects with that of potassium chloride (KCl).
Methods
A total of 14 studies of the effect of alkaline potassium salts on calcium metabolism and bone health, identified by a systematic literature search, were analysed with Review Manager (Version 5; The Cochrane Collaboration) using a random-effects model. Authors were contacted to provide missing data as required. Results are presented as the standardised (SMD) or unstandardized mean difference (MD) (95 % confidence intervals).
Results
Urinary calcium excretion was lowered by intervention with both KHCO3 (P = 0.04) and KCitr (P = 0.01), as was net acid excretion (NAE) (P = 0.002 for KHCO3 and P = 0.0008 for KCitr). Both salts significantly lowered the bone resorption marker NTX (P < 0.00001). There was no effect on bone formation markers or BMD. KHCO3 and KCitr lowered calcium excretion to a greater extent than did KCl.
Conclusions
This meta-analysis confirms that supplementation with alkaline potassium salts leads to significant reduction in renal calcium excretion and acid excretion, compatible with the concept of increased buffering of hydrogen ions by raised circulating bicarbonate. The observed reduction in bone resorption indicates a potential benefit to bone health.