No lipid lowering effect of vitamin D supplements found on statin users.

Abstract

Background Tromsø endocrine research group has performed multiple RCTs with vitamin D supplements/placebo and effects on different outcomes. Compiling data from four of these studies I tested an hypothesis established by Kane et al. in 2013, which suggests that vitamin D supplements have a significant lipid lowering effect in statin users. Retesting hypotheses in general is vital to the scientific community. By using patient data from Tromsø endocrine research group I wanted to retest this new hypothesis because it has not been confirmed by other studies. Method To test the hypothesis I pooled subjects from four vitamin D intervention studies and split the subjects into statin users and non-statin users. I then performed independent samples t-test to see if vitamin D-supplements during 6-12 months had a lipid lowering effect compared to placebo. I performed correlations between baseline levels of vitamin D and lipids. To adjust for confounding factors in the correlations I used linear regression with age, sex and BMI as covariates. Results At baseline serum HDL, Apo-A and triglycerides correlated significantly with vitamin D (p < 0.01). After adjusting for confounders the baseline HDL levels correlated significantly with vitamin D (p=0.001). I found no significant results in the t-test or the linear regressions on changes in lipid levels based on vitamin D treatment. Conclusions I found no clear significant lipid-lowering effect of vitamin D supplementation compared to placebo in neither statin users nor non-statin users. After adjusting for confounders, serum HDL still remained significantly correlated with vitamin D at baseline.