800 IU (20 mcg) per day increases vitamin D blood levels 8 ng/ml (20 nmol/L). 1000 IU (25 mcg) per day increases vitamin D blood levels 10 ng/ml (25 nmol/L). 2000 IU (50 mcg) per day increases ...

A 21-year-old man or women exposed to summer UVB light generates 10,000 IU (the equivalent of 250 mcg, 25 multivitamin pills of vitamin D, or 100 glasses of milk) of vitamin D in 15 to 20 minutes.

A daily vitamin D intake of more than 100 micrograms (4,000 IU) is dangerous. Children between the ages of 1 and 10 should consume no more than 50 micrograms (2,000 IU) per day. Under-12-month infants ...