CHEVY CHASE, Md.—Low levels of vitamin D and high levels of parathyroid hormone are associated with increased mortality in black and Caucasian older adults, according to a new study accepted for publication in Journal of Clinical Endocrinology and Metabolism (JCEM). The findings also suggest the potential impact of remediating low vitamin D levels is greater in blacks than Caucasians because vitamin D insufficiency is more common in blacks.
Low levels of vitamin D have been directly associated with various forms of cancer and cardiovascular disease. Most studies regarding the health effects of low vitamin D levels have been conducted on persons of European origin, but the current study examines the relationship between vitamin D and mortality in blacks and Caucasians.
The Second National Report on Biochemical Indicators of Diet and Nutrition report published in April 2012 by the Centers for Disease Control and Prevention (CDC) found deficiency rates for vitamins and nutrients vary by age, gender, or race/ethnicity and can be as high as 31% for vitamin D deficiency in non-Hispanic blacks.
“We observed vitamin D insufficiency in one-third of our study participants. This was associated with nearly a 50% increase in the mortality rate in older adults," said Stephen B. Kritchevsky, PhD, Professor of Internal Medicine and Transitional Science at the Wake Forest School of Medicine, and lead researcher of the study. “Our findings suggest that low levels of vitamin D may be a substantial public health concern for our nation’s older adults."
For the study, 2,638 Caucasians and blacks aged 70-79 years were asked to fast for 12 hours, after which a blood sample was collected to determine levels of vitamin D. Every six months study participants were contacted to ascertain their medical condition. The study determined the proportion of deaths among participants of with different vitamin D levels. In addition to many health factors, the time of year was also taken into account due to the seasonal effects on vitamin D. Researchers found levels of vitamin D less than 30 ng/ml were associated with significantly increased all-cause mortality.
“We all know that good nutrition is important to overall health, and our study adds to a growing body of literature that underscores the importance of vitamin D and indicates that poor vitamin D nutrition is widespread," said Kritchevsky. “The good news is it’s easy to improve vitamin D status either through increased skin exposure to sunlight or through diet or supplements."
A 2010 study conducted by researchers from Emory University found almost 75% of healthy, low-income, minority children were low in vitamin D. They also found age and season were significant predictors of vitamin D deficiency, and most children get their vitamin D through fortified milk.