膳食蛋白质水平及含硫氨基酸对人体钙代谢的影响

STUDIES ON THE EFFECT OF PROTEIN AND SULFUR CONTAINING AMINO ACIDS ON CALCIUM METBOLISM AND BALANCE IN HUMAN

目的：了解在我国实际膳食情况下，增加蛋白质摄入量对钙代谢的影响。方法：７名２４～３１岁的健康男性青年于４个实验期中分别轮流摄取四种不同的膳食，包括：基础膳食；基础膳食加４０ｇ鸡蛋白蛋白质；基础膳食加蛋氨酸１．９ｇ和胱氨酸１．７ｇ；以及基础膳食加牛磺酸２．４ｇ。然后观察尿钙、钙吸收及钙平衡的变化。结果：各膳食期钙的表观吸收率均无差异，补充蛋白质或补充蛋氨酸和胱氨酸使尿硫酸根及尿钙排泄量显著高于基础膳食期，并且钙平衡也均降低。补充牛磺酸对尿钙和钙平衡均无影响。

Seven young Chinese men,aged 24 to 31 years,were selected for the study.An increase in protein intake from about 67g to 107g while maintaining calcium,phosphorus intake constant caused an increase in urinary calcium and sulfate,and a decrease in calcium balance.Supplement of methionine and cystine in amount to simulate those in the high protein diet had a similar effect.Adding taurine to the diet had no effect on urinary calcium,urinary sulfate and calcium balance.Calcium absorption was not affected by increasing protein intake or supplementation of sulfur containing amino acids.This study indicated that the adverse effect of increasing protein intake on calcium balance might relate to increased sulfate excretion from the catabolism of methionine and cystine.