Effect of Vitamin D Oral Supplements on 25 OH Vitamin D Levels

Vitamin D deficiency is common world wide. 25 OH vitamin D level is the best indicator of vitamin D status. Vitamin D supplements are available as vitamin D2 or D3, in small daily or large weekly/monthly doses. Controversy continues on the relative potency of vitamin D2 compared to D3 and of daily compared to weekly or monthly doses, in increasing/maintaining total 25 OH vitamin D level. The investigators plan to conduct a controlled trial to compare the effect of various vitamin D supplements on 25 OH vitamin D levels in healthy adults with starting 25 OH vitamin D level between 20 to 50 nmol/L.