The study – published in the open access journal BMC Medicine – reports that twice daily consumption of a yoghurt drink enriched with vitamin D3 results in improved blood sugar management, lowered insulin resistance, normalised cholesterol levels, and improved markers of endothelial dysfunction – a precursor of heart disease.
"Patients who had taken the vitamin D yoghurt also had improved cholesterol levels with lower total cholesterol and LDL levels and an increase in HDL. All the improvements in cholesterol seemed to be due to the reduction in insulin resistance,” said Dr Tirang Neyestani of the researchers, based at the National Research Institute and Faculty of Nutrition and Food Technology at Shahid Beheshti University of Medical Sciences, Iran.
“Biomarkers of endothelial dysfunction, serum endothelin-1, E-Selectin and MMP-9, levels were also lower for the patients taking vitamin D," he added.
The researchers noted that low vitamin D status is known to affect the inner lining of blood vessels (endothelial cells),eventually leading to atherosclerosis and cardiovascular disease. In addition they noted that people with diabetes are known to have an increased risk of heart disease.
The researchers suggested that endothelial function “may therefore be the focus of preventive efforts against both diabetes and its fatal complications.” They noted that by improving vitamin D status in diabetic people, it may be possible to improve endothelial biomarkers, possibly reducing the risk of heart disease.
In the double-blind trial, the researchers from Tehran gave diabetic patients either a plain yoghurt drink (Doogh) or the same drink fortified with vitamin D3 twice a day for 12 weeks. The team measured the effects of vitamin D on glycemic status, cholesterol levels and endothelial biomarkers.
The team found that vitamin D improved the fasting glucose, insulin resistance, cholesterol, and measures of endothelial function.
“The intervention resulted in a significant improvement in fasting glucose, the Quantitative InsulinCheck Index (QUICKI), glycated hemoglobin (HbA1c), triacylglycerols, high-density lipoprotein cholesterol (HDL-C), endothelin-1, E-selectin and MMP-9 in the fortified yoghurt drink compared to the plain yoghurt drink,” wrote the researchers.
The team noted that most patients in the trial were deficient in vitamin D at the start, but the fortified yoghurt drink elevated most of their levels to normal. However, they said that even amongst those who took the vitamin D supplement, around 5% remained deficient, and did not show any signs of improvements associated with increased status.
Source: BMC Medicine
Published open access online, doi:
“Regular consumption of vitamin D-fortified yogurt drink (Doogh) improved endothelial biomarkers in subjects with type 2 diabetes: a randomized double-blind clinical trial”
Authors: S. Shab-Bidar, T.R. Neyestani, A. Djazayery, M.R. Eshraghian, A. Houshiarrad, et al