今天在COSTCO看到两种补钙的:
一种是“Calcium 600mg with 200 iu vitamin D supplement, From oyster shell”,卖$5.69
另一种是“Calcuim 600mg High potency Calcium, Naturally sourced from limestone”,卖$12.49
两种都标明“1500mg providing 600 elemental calcium”,数量也一样“500 tablets”,但为什么价钱却差这么多?哪种补钙效果好啊?