I don't know what Ray's specific guidelines on daily intake of vitamin D are, but I have seen him express opinion that 400 IU - 800 IU is likely too low to make a difference. This study claims that the current guidelines are underestimated by a factor of 10, so a person should really be ingesting north of 4,000 IU of vitamin D3 daily.
If true, this may explain why most studies with vitamin D did not see effects with doses of less then 3,000 IU.
http://www.newswise.com/articles/scient ... ar-too-low
If true, this may explain why most studies with vitamin D did not see effects with doses of less then 3,000 IU.
http://www.newswise.com/articles/scient ... ar-too-low