Lead author Dr. Manish Ponda, assistant professor of clinical investigation in Dr. Jan Breslow's laboratory of biochemical genetics and metabolism at The Rockefeller University in New York, and colleagues studied 151 people with vitamin D deficiency who received either a mega-dose -- 50,000 internationals units -- of vitamin D3 or placebo weekly for eight weeks.
Participants' cholesterol levels were measured before and after treatment.
"Our study challenges the notion that vitamin D repletion improves cholesterol levels," Ponda said in a statement. "These clinical trial results confirm those from a recent data mining study."
As expected, replenishing subjects with high-dose supplements of oral vitamin D decreased parathyroid hormone levels and increased calcium levels -- changes linked to participants' increase in low-density lipoprotein, or the "bad," cholesterol.
"For example, participants receiving vitamin D who had an increase in calcium levels experienced a 7 percent increase in LDL cholesterol, while those whose calcium levels fell or did not change had a 5 percent decrease in LDL cholesterol," Ponda added.
The findings were published in the journal Arteriosclerosis, Thrombosis and Vascular Biology.