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.
In clinical trials, at least 80% of patients take their medicine. (If they don't, they wind up being nagged by counselors.) "Try getting that kind of compliance for a diet or exercise program, " he says.