Heaney R P, Barger-Lux M J
Creighton University, Omaha, NE 68178.
J Dairy Sci. 1994 May;77(5):1155-60. doi: 10.3168/jds.s0022-0302(94)77052-1.
Calcium is the fifth most abundant element in the earth's crust and is necessary for both plant and animal life today. Moreover, the natural diets of all mammals are rich in calcium. The diet of Stone Age human adults is estimated to have contained from 50 to 75 mmol of calcium (2000 to 3000 mg)/d, three to five times the median calcium intake of present-day US adults. Human physiology has adapted to this environmental abundance with an intestinal absorptive barrier and inefficient renal conservation of calcium. Although mammalian physiology contains mechanisms by which organisms can adjust to temporary environmental shortages, chronic calcium retention has a number of health consequences, most notably bone fragility, high blood pressure, and colon cancer. Evidence indicates that improvement in calcium intake (or in vitamin D status) prevents some portion of each of these multifactorial problems. At least 14 intervention studies have established the skeletal benefit of increased calcium intake during growth and among women in the late postmenopause. Other evidence suggests that adequate calcium may protect against salt-sensitive and pregnancy-associated hypertension and that high intakes of both dietary calcium and vitamin D reduce development of precancerous changes in colonic mucosa.
钙是地壳中含量第五丰富的元素，是当今动植物生存所必需的。此外，所有哺乳动物的天然饮食中都富含钙。据估计，石器时代成年人类的饮食中每天含有50至75毫摩尔的钙（2000至3000毫克），是当今美国成年人钙摄入量中位数的三到五倍。人类生理学通过肠道吸收屏障和低效的肾脏钙保留机制适应了这种丰富的环境。尽管哺乳动物生理学包含生物体可以适应暂时环境短缺的机制，但长期钙潴留会产生许多健康后果，最显著的是骨质脆弱、高血压和结肠癌。有证据表明，增加钙摄入量（或改善维生素D状况）可预防这些多因素问题中的一部分。至少有14项干预研究证实了在生长期间和绝经后期女性增加钙摄入量对骨骼有益。其他证据表明，充足的钙可能预防盐敏感性高血压和妊娠相关高血压，并且高钙饮食和维生素D摄入量都可减少结肠黏膜癌前病变的发生。
