Chronic deficiency may be a factor in the development of osteoporosis or osteomalacia (softening of bone) and may contribute to hypertension and colon cancer.

钙缺乏可致骨质疏松或骨质变软，还可能和高血压，结肠癌的发生有关。

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Since the 1930s, most milk in the U.S. has been fortified with D to prevent rickets, a bone-softening disease.

WSJ: Vitamin D to Defend Against Disease