A good daily intake of Vitamin D is now considered to be 2,000 i.u. to 4000ius. Some researchers are advising daily intake of 8,000 i.u.

D3 is the ideal form of Vitamin D to take as a supplement. The human body has control mechanisms in place that regulate conversion of D3 to its hormonal form, whereas D2 is foreign to the body, lacks controls, and can actually be too aggressive, causing deposition of calcium into soft tissues such as the arteries and muscles, a side effect not shared with D3