Vitamin D Deficiency May Contribute to Clogged Arteries in People with Type 2 Diabetes

A vitamin D deficiency is common among people with type 2 diabetes, and having a low level of the vitamin doubles their risk for developing heart disease–the leading cause of death in these patients. Thus, understanding the connection between heart disease, vitamin D, and diabetes is a critical area of research.  

Atherosclerosis, a condition where fats and cholesterol build up in the walls of blood vessels, disrupting blood circulation throughout the body and to the heart, is a key contributor to heart disease. In a recent Association-supported study, investigator Carlos Bernal-Mizrachi, MD, at Washington University School of Medicine in St. Louis, has found that low levels of vitamin D may play a causal role in atherosclerosis in people with type 2 diabetes.

In a November 9, 2012 article in the Journal of Biological Chemistry, Dr. Bernal-Mizrachi found that when the patients’ vitamin D levels dipped below the normal range, a type of white blood cell that normally circulates freely in the blood was more apt to transform into stagnant immune cells called macrophages. When macrophages stick to the walls of blood vessels, they make it more likely for cholesterol to accumulate as plaques. Cholesterol build-up causes the arteries to harden and block blood flow, which can ultimately lead to heart failure.

The researcher accounted for factors like blood pressure, body weight, gender, and race, but only vitamin D levels influenced whether the macrophages adhered to blood vessels. In further experimentation, Dr. Bernal-Mizrachi saw that adding vitamin D to the macrophages suppressed their adhesion.

“In the future, we hope to generate medications, potentially even vitamin D itself, that help prevent the deposit of cholesterol in the blood vessels,” said Dr. Bernal-Mizrachi. “Our ultimate goal is to intervene in people with diabetes to determine whether vitamin D might decrease inflammation, reduce blood pressure, and lessen the likelihood that they will develop atherosclerosis or other vascular complications.”

In a different study also funded by the ADA, Dr. Bernal-Mizrachi is exploring the racial differences in diabetes, focusing on the effects of vitamin D on cardiac risk in the African-American population. His clinical trial will determine whether giving vitamin D supplements to these patients can delay or even reverse the progression of heart disease.  

(A. E. Riek, J. Oh, J. E. Sprague, A. Timpson, L. de las Fuentes, L. Bernal-Mizrachi, K. B. Schechtman, C. Bernal-Mizrachi. Vitamin D Suppression of Endoplasmic Reticulum Stress Promotes an Antiatherogenic Monocyte/Macrophage Phenotype in Type 2 Diabetic Patients. Journal of Biological Chemistry, 2012; 287 (46): 38482 DOI: 10.1074/jbc.M112.386912)