Taking vitamin D supplements to compensate for vitamin D deficiency didn’t improve cholesterol  — at least in the short term, according to new research in Arteriosclerosis, Thrombosis and Vascular Biology, an American Heart Association journal.

 Researchers 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.

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

 “Our study challenges the notion that vitamin D repletion improves cholesterol levels” said Manish Ponda, M.D., M.S., study lead author and assistant professor of clinical investigation in Dr. Jan Breslow’s laboratory of biochemical genetics and metabolism at The Rockefeller University in New York, N.Y. “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 — physical functional changes that were linked to participants’ increase in low-density lipoprotein  (LDL, 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 said.

 The study questions the use of vitamin D supplements to improve cholesterol, Ponda said.  Questions remain about whether increasing vitamin D levels with exposure to sunlight, the predominant natural source, would have a different effect than with high-dose oral supplements.

Co-authors are Kathleen Dowd, R.N.; Dennis Finkielstein, M.D.; Peter R. Holt, M.D.; and Jan L. Breslow, M.D.