Vitamin Information Center

Vitamin D is the key to preventing rickets and osteoporosis, but Rockefeller University scientists suspect it may also play a role in heading off atherosclerosis in people with chronic kidney disease. In a new clinical study, investigators at The Rockefeller University Hospital are examining patients with moderately reduced kidney function to investigate the effect of vitamin D therapy on endotoxemia, a condition that is common among those with renal disease and is widely viewed as a contributor to heart disease. The study, led by Instructor in Clinical Investigation Manish Ponda, is partially funded by a $25,000 grant from the Center for Clinical and Translational Science.

The high rate of atherosclerosis among patients with kidney disease is well documented but little understood by medical experts. Endotoxins, products of the natural breakdown process of bacteria, are a hot topic of clinical investigation with regard to both heart and kidney disease. “The number one killer among people with kidney disease is heart disease, just like in the rest of the population, except that in people with kidney disease, the heart disease exhibits an accelerated course,” says Ponda, a member of Jan Breslow’s Laboratory of Biochemical Genetics and Metabolism at Rockefeller. The research is an extension of earlier clinical work by Ponda that showed a high incidence of vitamin D deficiency among early-stage kidney disease patients.

Study participants — males and postmenopausal females between ages 50 and 80 with stage three chronic kidney disease and vitamin D deficiency — will be provided with thrice-weekly doses of vitamin D3, also known as cholecalciferol, the form of vitamin D produced by the body in response to sunlight. Participants will make three outpatient visits at intervals of four weeks each to The Rockefeller University Hospital, where investigators test for levels of endotoxins in response to vitamin D repletion.

The dose of vitamin D prescribed for the study — 30,000 international units per week — equals more than 20 times the intake recommended by the United States Department of Agriculture and approximately 10 times the amount in an average multivitamin supplement. The dosage is designated to safely reverse vitamin D deficiency.

If Ponda’s hypothesis — that vitamin D repletion will be accompanied by decreases in blood endotoxin levels — holds true, a larger, more-extensive, “progression” study will follow, to chart the connection over longer periods of treatment and in later stages of renal disease. “Kidney disease puts a person at significantly higher risk for cardiovascular disease, but it is often asymptomatic even as late as stage three,” says Ponda. “The more definitively we can characterize renal disease, the closer we are to effectively treating both it and its comorbid conditions.”

Chronic kidney disease patients may see their risk of death drop by one quarter if they take a form of vitamin D, a new study says.

In a study of more than 1,400 people with chronic kidney disease, those that were taking the drug calcitriol, a form of activated vitamin D, had a 26 per cent reduction in their risk of death versus those who were not on the drug. Overall, the patients on calcitriol had their risk of either death or dialysis due to a loss of kidney function fall by 20 per cent.

The study is published in the Journal of the American Society of Nephrology.

A healthy human body uses first the liver and then the kidneys to convert vitamin D obtained through diet and sunlight into an active form that the body can use. However, it is believed that patients with chronic kidney disease are unable to do complete the second step.

They are often prescribed activated vitamin D to help lower elevated levels of the parathyroid hormone, which can lead to a weakening of the bones. However, people with kidney disease often suffer from calcified, or stiff, blood vessels, which can lead to a host of cardiovascular problems. Vitamin D increases calcium levels in the blood, which doctors fear could exacerbate this problem.

“We did find that people who got the activated vitamin D drug did have a higher risk of having a high calcium level in the blood,” study author Dr. Bryan Kestenbaum of the University of Washington told Ctv.ca.

“But the overall amount of people that that happened to was relatively small, and the overall balance was that people who got the activated vitamin D drug survived longer.”

Kestenbaum speculated that vitamin D leads to decreased mortality rates because of its known ability to lower risk factors for cardiovascular disease, including high blood pressure, diabetes and inflammation.

He said that the next step in this field of research would be to conduct randomized clinical trials to confirm vitamin D’s effect on survival rates among patients with kidney disease.