Sakineh Shab-Bidar and colleagues at the National Research Institute and Faculty of Nutrition and Food Technology and Tehran University of Medical Sciences said not having enough vitamin D affects the inner lining of blood vessels -- endothelial cells -- eventually leading to atherosclerosis and cardiovascular disease.
In a double-blind trial, researchers investigated the effect of vitamin D on the glycemic status, cholesterol levels and endothelial biomarkers of diabetics. Patients were given either a plain yogurt drink or the same drink fortified with vitamin D, twice a day for 12 weeks.
Patients who had taken the vitamin D yogurt also had improved cholesterol levels with lower total cholesterol and low-density lipoprotein, the "bad," cholesterol and an increase in high-density lipoprotein, the "good," cholesterol.
All the improvements in cholesterol seemed to be due to the reduction in insulin resistance, the study said.
"Most of our patients were deficient in vitamin D at the start of the trial but the fortified yogurt drink elevated most of their levels to normal," Abolghassem Djazayery said in a statement. "However, even amongst those who took the vitamin D supplement, about 5 percent remained deficient at the end of the 12 weeks. These people did not show the same improvements. Nevertheless for most diabetics with vitamin D deficiency this is an easy way to improve their outcome."
The findings were published in the journal BMC Medicine.