The FDA approves of 200 IU for 19-50 year olds; 400 IU for people over 50. Most vitamin pills contain 400 IU of vitamin D.

FDA推荐19-50岁的人摄入200国际单位，50岁以上摄入400国际单位。大部分维生素片含有400国际单位的维生素D。

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The latest RDAs of vitamin D increased to 600 IU for adults up to the age of 70 and 800 IU for adults older than 70, and the tolerable upper limit increased from 2, 000 to 4, 000 IU per day for adults.

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The AI for vitamin D is 200 International Units for adults under age 50, 400 IU for those 51 to 70, and 600 IU for those age 71 and above.

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The recent Institute of Medicine study recommends everyone age 1 to 70 take 600 international units (IU) per day of vitamin D and those over 71 take 800 IU. The institute recommends adolescents age 9 to 18 receive 1, 300 mg per day of elemental calcium.

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