The Effect of Vitamin D Repletion on Small Low Density Lipoprotein (LDL) Particle Number in Subjects at Elevated Cardiovascular Risk

Vitamin D is a fat-soluble vitamin that is naturally present in very few foods, added to others, and available as a dietary supplement. It is also produced in the body when ultraviolet rays from sunlight strike the skin and trigger vitamin D synthesis. Vitamin D is essential for promoting calcium absorption and maintaining adequate serum calcium and phosphate concentrations to enable normal mineralization of bone and bone growth. Without sufficient vitamin D, bones can become thin, brittle, or misshapen. Vitamin D sufficiency prevents rickets in children and osteomalacia in adults. Together with calcium, vitamin D also helps protect older adults from osteoporosis. Many people have low levels of Vitamin D. Replacing Vitamin D is thought to help lower the risk of heart disease. Vitamin D may be helpful, but it could also be harmful. The investigators are studying the effect of Vitamin D on the level of a harmful kind of cholesterol. Participants will have their cholesterol levels measured and then receive either Vitamin D or a placebo. After 2 months of treatment, the investigators will measure their cholesterol levels again.