Eight subjects received 100,000 I.U. of vitamin D and seven subjects received phototherapy. At the onset of treatment and after 1 month of therapy subjects were administered the Hamilton Depression scale, the SIGH-SAD, and the SAD-8 depression scale. All subjects receiving vitamin D improved in all outcome measures. The phototherapy group showed no significant change in depression scale measures.
There's a growing body of evidence that the U.S. RDA (400 IU/day, just enough to prevent rickets) is an
Maximum endogenous production with full body exposure to sunlight is 250 µg (10,000 IU) per day. [ ... ] dosages up to 250 micrograms (10,000 IU) /day in healthy adults are believed to be safe. [ ... ] all known cases of vitamin D toxicity with hypercalcemia have involved intake of or over 1,000 micrograms (40,000 IU)/day.