[RayChuang88]

That's why people need to start taking more Vitamin C, D3 and E and the mineral zinc starting at the autumnal equinox in the USA. I cite this article:

Time for more Vitamin D

[Cold Heart]

Informative, Thanks

[Ragnar54]

Actually, you need a lot more than 1000 IU per day.

Immunologic Effects of Vitamin D on Human Health and Disease

“Although most of the biologic effects of vitamin D have been related to its active metabolite there continues to be intriguing evidence that vitamin D itself may have its own biologic actions independent of its metabolism. Our hunter gatherer forefathers likely maintained serum vitamin D levels in the range of 10–50 ng/mL (25–125 nmol/L). This is supported by the observation that Maasai herders and Hadza tribesmen maintained serum 25(OH)D in the range of 40–60 ng/mL (100–150 nmol/L) [12,13]. To maintain these blood levels, a person would require ingesting approximately 4000–6000 IUs daily."

[gleeaikin]

I have read your Vitamin D3 link. Unfortunately, they consider a blood test level above 20ng/mL as adequate, but most of the people committed to recommending D3, talk about levels of 50 or 70 and even somewhat higher as optimum.