New research published in the Journal of Clinical Endocrinology and Metabolism suggests that vitamin D supplementation only affects cholesterol levels in those taking a statin.
Previous studies have found no effect of vitamin D supplementation on lowering LDL cholesterol levels. This has been a bit perplexing to researchers, as vitamin D levels often inversely correlate with LDL cholesterol levels, yet improving vitamin D status doesn’t improve LDL scores.
Recently, Lynn Kane, RN, and colleagues at the University of California, San Francisco, put vitamin D back to the test, to see if vitamin D supplementation could improve cholesterol, cholesterol subfractions, or triglyceride measurements.
They randomized 51 adults to take 1,000 IU/day of vitamin D or a daily placebo pill. The trial lasted for 12 weeks, measuring vitamin D status, cholesterol, tryglcerides and a few other things at 0, 6 and 12 weeks. In the vitamin D group, if the patient still tested below 20 ng/ml after 6 weeks, the researchers increased their intake to 2,000 IU/day.
At the end of the trial, the researchers observed no effect of vitamin D supplementation on cholesterol, cholesterol subfractions, or triglyceride measurements in the total group of subjects randomized to vitamin D compared to those randomized to placebo.
However, when the researchers only looked at patients on atorvastatin, a statin marketed under the name Lipitor, they noticed that vitamin D indeed lowered LDL cholesterol. Vitamin D in atorvastatin patients lowered total cholesterol by 12% and LDL cholesterol by 14% (P=.05) compared to placebo.
Why is this? It may have something to do with vitamin D affecting absorption of cholesterol.
Paradoxically, while statins decrease cholesterol synthesis, they also upregulate cholesterol absorption. One marker for cholesterol absorption is a plasma sterol called campesterol. The higher the campesterol, the higher the cholesterol absorption.
In this study, the researchers found that patients that took atorvastatin and vitamin D, campesterol decreased significantly after 12 weeks, compared to no change in the atorvastatin and placebo group. Furthermore, when the researchers looked at campesterol levels in the entire vitamin D group, whether or not they were taking atorvastatin, there was no relationship.
This means that vitamin D and atorvastatin taken together best lowered LDL and total cholesterol. The researchers call for further research in the area. In the meantime, under the care and supervision of a doctor, vitamin D could be used to compliment Lipitor in attempt to lower LDL and total cholesterol.