How low vitamin D boosts heart risks for diabetics

Kathleen Blanchard's picture
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Researchers know that low vitamin D levels doubles the risk of heart disease among diabetics, but they have not known why. Research from Washington University School of Medicine in St. Louis have discovered that diabetics cannot process cholesterol when vitamin D levels are low, causing plaque to build up in the arteries. The result is greater risk of heart attack and stroke, especially for diabetics.

The solution is simple – diabetics can increase their intake of vitamin D to reduce the chances of developing heart disease.

Investigator Carlos Bernal-Mizrachi, M.D., a Washington University endocrinologist at Barnes-Jewish Hospital explains, "Vitamin D inhibits the uptake of cholesterol by cells called macrophages. When people are deficient in vitamin D, the macrophage cells eat more cholesterol, and they can't get rid of it. The macrophages get clogged with cholesterol and become what scientists call foam cells, which are one of the earliest markers of atherosclerosis”, otherwise known as hardening of the arteries.

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The researchers believe that because diabetes is associated with greater inflammation in the blood vessels, macrophages loaded with cholesterol are prevalent, putting diabetics at increased risk for heart disease.

The researchers studied macrophages, comparing them to people with and without diabetes. When the cells of diabetics were exposed to cholesterol, foam cells developed in the presence of low vitamin D.

Dr. Bernal-Mizrachi explains, "Cholesterol is transported through the blood attached to lipoproteins such as LDL, the 'bad' cholesterol. As it is stimulated by oxygen radicals in the vessel wall, LDL becomes oxidated, and macrophages eat it uncontrollably. LDL cholesterol then clogs the macrophages, and that's how atherosclerosis begins."

When adequate vitamin D is present, macrophages don’t eat cholesterol, and foam cells do not develop. Diabetics might benefit from increased vitamin D intake from supplements, given concerns about how much sun exposure is safe. Sunshine exposure for just a few minutes at a time might also work says Dr. Bernal-Mizrachi. The study suggests that boosting vitamin D levels can reduce risk of heart disease among diabetics by helping the body get rid of cholesterol.

Washington University in St. Louis

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