SAN DIEGO – Raising levels of vitamin D, deficient in many patients with chronic kidney disease, improved vascular function and reduced inflammation and vessel wall stiffness after 16 weeks, according to results of a study in a small group of early kidney disease patients in India.
“This tells us that vitamin D has the potential, at least over the short- to intermediate term, to improve vascular function,” with a promise of reducing or preventing cardiovascular outcomes in a larger study, said Dr. Vivekanand Jha, of the George Institute for Global Health in New Delhi.
“Patients with very early kidney disease are at very high risk of developing cardiovascular complications such as heart attacks, strokes, and peripheral vascular disease – and that’s what kills them before they get to the point where they need dialysis,” Dr. Jha said. “So, many die before they need dialysis. But we don’t know the factors that cause these cardiovascular complications.”
His group hypothesized that because vitamin D has biological action on blood vessels, “if we supplemented patients with vitamin D, their vascular function would improve.”
Participants were randomized to receive directly observed oral doses of 300,000 IU of cholecalciferol at baseline and at 8 weeks, or directly observed doses of a placebo in a matched control arm.
“We measured several parameters to look at vascular function after 16 weeks and found that patients who received vitamin D showed normalized vitamin D and decreases in levels of parathyroid hormone,” Dr. Jha said at the meeting sponsored by the American Society of Nephrology.
“But most importantly, we found that vitamin D recipients showed improvement in their vascular function on two or three tests; in flow-mediated dilation, which suggests improved endothelial function; and improved augmentation index, which looks at the stiffness of blood vessels,” he explained.
The next step is a much larger study designed to show that vitamin D supplements in this population can prevent cardiovascular events. “But that’s going to be a long-term study,” Dr. Jha noted.
“I don’t want to get ahead of myself and say that this is going to cure cardiovascular problems,” Dr. Jha cautioned. “But now we know we need to do a definitive study to look at these events, and prove whether supplementation with vitamin D does or does not significantly improve those endpoints.”