VitD has numerous hormonal effects, including regulation of Ca2+ and Mg2+, as well as effects on numerous genes, including insulin and androgens. Mounting literature demonstrates associations between VitD insufficiency and cancer, diabetes and heart disease. VitD insufficiency, defined by concentration of serum 25-hydroxycholecalciferol (25-OHD) <33ng/ml (82.5 nmol/ml), is common at all latitudes; the prevalence is estimated at ~35% in "healthy" populations. VitD testing and replacement is gaining popularity in clinical practice. It is not known whether there is a difference in the effect of equivalent doses of emulsified vs. non-emulsified cholecalciferol (VitD3) supplementation, reflected by quantitative changes in serum 25-OHD. However, clinical observations revealed that in an average of 4.4 months, subjects taking 4000 iu daily of the emulsified form of cholecalciferol improved their 25-OHD levels by 6.76 ng/mL more than those taking 5,000 iu daily of the non-emulsified form. The safety of taking 10,000 IU/day has been confirmed. Taking this dose for 12 weeks should cause a robust increase in serum 25-OHD. This study will provide preliminary data comparing three high quality VitD3 supplements, one a powdered capsule, one a chewable tablet, and the other a lipid-emulsified liquid. Future studies will compare the "better" supplement to conventional VitD replacement using VitD2.