Data from previous trials suggest a protective role of vitamin D in cardiovascular disease. A recent meta-analysis of trials with at least 5 years of follow-up of vitamin D supplementation concluded that intake of vitamin D supplements may decrease total mortality, but that the relationship between baseline vitamin D status, dose of vitamin D supplements, and total mortality rates remains to be investigated. An even more recent analysis of vitamin D concentrations found that participants with vitamin D deficiency and hypertension were about twice as likely as people without hypertension and vitamin D deficiency to have a cardiovascular event during the study.~The main hypothesis to be tested is that normalization of vitamin D levels will lower LDL-cholesterol and total cholesterol concentrations in people with inadequate vitamin D concentrations as determined by circulating 25-OH vitamin D. Subhypotheses are that HDL-cholesterol, triglycerides, lipoprotein(a), hs C-reactive protein and Hemoglobin A1c will not be affected, and that cyp3a-metabolized medication levels will decrease with vitamin D replacement.~This is a 12-week randomized double-blind dose titration study of the effects of supplementation with 1000-2000 IU vitamin D on lipid and vitamin D concentrations. Dietary intake of vitamin D will be estimated by dietary recall questionnaire or analysis of three non-consecutive 24-hour dietary intake logs.
The purpose of this study is to examine whether oral vitamin D supplementation in people with inadequate vitamin D concentrations will lower LDL-cholesterol and total cholesterol concentrations.