Do Vitamin D Levels Affect Cholesterol?
Higher vitamin D levels appear to be associated with higher total cholesterol levels and higher HDL cholesterol levels, according to a new study presented at the American College of Cardiology’s (ACC) 65th Annual Scientific Sessions.1
Investigators looked 13 039 adults and found that higher 25-hydroxyvitamin D (25[OH]D) was cross-sectionally and prospectively associated with higher total cholesterol and HDL cholesterol levels and lower total cholesterol-to-HDL cholesterol ratio after considering factors such as diabetes and adiposity.
“We wanted to see the association of low vitamin D with low HDL cholesterol and high total cholesterol-to-HDL cholesterol ratio, but I think we were most surprised to not find an association of vitamin D deficiency with elevated triglycerides, as has been noted in other studies. This may be in part that we carefully adjusted for other confounding lifestyle variables such as physical activity and 2 measures of adiposity (BMI and waist circumference),” said senior study author Erin Michos, MD, MHS, associate professor of medicine and epidemiology and associate director of preventive cardiology at Johns Hopkins School of Medicine in Baltimore.
“We also were surprised that we did not see any association of low vitamin D with elevated LDL cholesterol in our overall sample. However, when we performed a sensitivity analysis looking at individuals who were not taking lipid-lowering therapy at the baseline exam or at any of the follow-up visits, we did see the association of low vitamin D with elevated LDL cholesterol.”
Dr Michos and her colleagues measured lipids at baseline (1990-1992), in 1993-1994, and in 1996-1998. The mean follow-up was 5.2 years.
The investigators used linear and mixed model regression methods to assess associations of 25(OH) D with cross-sectional and lipid trends. They also adjusted for clinical characteristics. The mean age at baseline was 57.6 years, 57% were women, and 24% were black.
Among those individuals without baseline dyslipidemia, participants with low 25(OH) D (<20 ng/mL) compared with optimal levels (≥30 ng/mL) had increased risk for incident dyslipidemia in demographic-adjusted models (hazard ratio [HR]=1.19; 95% CI, 1.02-1.39). Nevertheless, this finding was attenuated in fully-adjusted models (HR=1.12; 95% CI, 0.95-1.32).1
Dr Michos said low concentrations of vitamin D, defined as serum 25(OH)D below 30 ng/mL, are present in more than two-thirds of the US adult population and in an estimated 1 billion individuals worldwide.
“So, this is a major relevant public health issue. Vitamin D deficiency has been associated with a number of non-bone-related adverse health outcomes, including increased risk for cardiovascular diseases (CVDs). One of the mechanisms by which vitamin D may influence CVD risk is through an effect on lipids,” Dr Michos told Endocrinology Advisor. “The potential link between vitamin D deficiency and adverse lipid profile should be of great interest to a large number of practitioners who treat both vitamin D and lipid disorders, including endocrinologists, internists, lipidologists, and cardiologists.”
Previous studies, including one study conducted by her team and recently published in the Journal of Clinical Lipidology, suggested that low levels of vitamin D were associated with an atherogenic lipid profile consisting of elevated LDL cholesterol, elevated triglycerides, and lower HDL cholesterol, noted Dr Michos.2 However, most of the evidence supporting this association was obtained in cross-sectional analyses.
For this current investigation, the researchers analyzed the association between vitamin D status and the lipid profile prospectively using data from the Atherosclerosis Risk in Communities (ARIC) study. This large study of a US community-based sample of blacks and whites collected data on numerous demographic, lifestyle, and clinical variables spanning multiple clinic visits. Unlike prior investigations, ARIC allowed for extensive adjustment of possible confounders over time, according to Dr Michos. It also contained information regarding initiation of lipid-lowering medication use during follow-up.
Dr Michos said further research is warranted, including randomized, controlled trials, to assess whether treating vitamin D deficiency can impact lipids and thereby influence CVD risk.
- Faridi K, Zhao D, Martin SS, et al. Vitamin D and Change in Lipids Over 5 Years: The Atherosclerosis Risk in Communities (ARIC) Study. Presented at: ACC 65th Annual Scientific Session & Expo; April 2-4, 2016; Chicago, IL.
- Lupton JR, Faridi KF, Martin SS, et al. Deficient serum 25-hydroxyvitamin D is associated with an atherogenic lipid profile: The Very Large Database of Lipids (VLDL-3) study. J Clin Lipidol. 2016;10(1):72-81. doi:10.1016/j.jacl.2015.09.006.