Study questions use of vitamin D supplements to improve cholesterol

Vitamin D has been touted for its beneficial effects on a range of human systems, from enhancing bone health to reducing the risk of developing certain cancers. But it does not improve cholesterol levels, according to a new study conducted at The Rockefeller University Hospital. A team of scientists has shown that, at least in the short term, cholesterol levels did not improve when volunteers with vitamin D deficiency received mega-doses of vitamin D. The finding is published in the journal Arteriosclerosis, Thrombosis and Vascular Biology.

The researchers, led by Manish Ponda, an assistant professor of clinical investigation in Jan Breslow's Laboratory of Biochemical Genetics and Metabolism, studied 151 people with vitamin D deficiency. The study participants were given either 50,000 internationals units of vitamin D3 or a placebo weekly for eight weeks. Participants' cholesterol levels were measured before and after treatment.

Correcting vitamin D deficiencies with high doses of oral vitamin D supplements did not change cholesterol levels, Ponda and his colleagues found, despite effectively increasing vitamin D to recommended levels. Vitamin D levels nearly tripled in the group that received supplements, but were unchanged in the placebo group.

"Our study challenges the notion that replenishing vitamin D improves cholesterol," says Ponda. "In fact, a biologic response to vitamin D was correlated with an increase in LDL cholesterol."

Ponda and his colleagues also tested the effect of vitamin D supplementation on lipoprotein particle size and number, biomarkers of cholesterol not typically measured in clinical practice, and found no change in response to increases in vitamin D.

These clinical trial results confirm those from a recent data mining study, published in July in the journal Circulation, conducted by the Breslow lab in collaboration with scientists at Quest Diagnostics. In that study, the researchers examined a de-identified dataset for 8,592 patients and showed that raising vitamin D levels from deficient to optimal levels had no statistically significant effect on LDL (bad) cholesterol, or triglycerides. Increasing vitamin D had a small, but clinically minimal impact on total and HDL (good) cholesterol. Both studies were supported by a Clinical and Translational Science Award from the National Center for Advancing Translational Science.

"This study raises questions about the use of vitamin D supplements to improve cholesterol," Ponda says. "Longer-term studies on the impact of vitamin D supplementation are needed to make stronger recommendations."