S. guidelines, issued in 1997, call for 200 international units from birth through age 50;400 IUs from 51 through age 70 and 600 IUs from 71 on.

• 美国1997年颁布的指导意见是，从出生到50岁每天应补充200国际单位(IU)，51-70岁补充400IU，71岁以上补充600IU。