SUNDAY July 26, 2008 (foodconsumer.org) -- A new study has found that low serum of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D are independently associated with all cause and cardiovascular mortality.

Previous studies found low serum levels of vitamin D or exactly 25-hydroxyvitamin D are linked with higher incidence of cardiovascular risk factors and disease.

25-hydroxyvitamin D also known as vitamin D₂: ergocalciferol or calciferol is the form of vitamin D tested to evaluate one’s vitamin D status.   In the kidney, 25-hydroxy vitamin D changes into 1,25-dihydroxy vitamin D, an active form of vitamin D.

In the study, Harald Dobnig, MD and colleagues from Medical University of Graz, Graz, Austria and other organizations followed 3258 male and female patients at an average age of 62 who were scheduled for coronary angiography.

The study subjects were divided into quartiles based on 25 hydroxyvitamin D and 1, 25-dihydroxyvitamin D levels within each month of blood drawings.   During the 7.7-year follow-up, 737 patients or 22.6 percent died of whom 463 died from cardiovascular cases.

Dobnig and colleagues found low serum vitamin D levels were inversely correlated to higher risk of death from cardiovascular disease.   The lower two 25-hydroxyvitamin D quartiles (7.6 and 13.3 ng/mL) were 2.08 times and 1.53 times more likely to die from all causes respectively than those in the highest 25-hydroxyvitamin D quartile (28.4 ng/mL).

The increased risk of dying from cardiovascular disease was similar. Those who were in the lower two quartiles were 2.22 times and 1.82 times more likely to die respectively than those who were in the highest quartile.

The associations between 1, 25-dihydroxyvitamin D and the higher risk of all cause and cardiovascular mortality were similar.

The associations were independent of coronary artery disease, physical activity and other possible factors.

The researchers also found that low 25-hydroxyvitamin D levels were significantly linked to variables of inflammation such as C - reactive protein and interleukkin 6 levels, oxidative burden, and cell adhesion.

Dobnig and colleagues concluded that "Low 25-hydroxyvitamin D and 1, 25-dihydroxyvitamin D levels are independently associated with all-cause and cardiovascular mortality."

The study was published in The Archives of Internal Medicine: Vol. 168 No. 12, June 23, 2008.