Vitamin D, Race, and Cardiovascular Mortality: Findings From a National US Sample

Both Drs Gouni-Berthold and Fuller raise critical questions that have enormous implications for addressing health disparities.

Dr Gouni-Berthold raises the issue of dose. Available research shows that doses shown to be ineffective in improving cardiovascular outcomes are too low to attain optimal serum levels of vitamin D, particularly among African Americans.(1)

Whether high doses improve cardiovascular outcomes in older persons will be addressed through a large, randomized controlled trial that is starting (www.VitalStudy.org) in which participants will receive 2,000 IU vitamin D as one of the arms of the study.

Dr Fuller's comments raise a more troubling question that will not be easily addressed. She correctly notes that African Americans have much higher rates of vitamin D deficiency across the entire life course than whites(2-4) and suggests as others have that currently recommended supplements are inadequate.

There is growing observational data supporting Dr Fuller's hypothesis that vitamin D deficiency represents a significant contributor to Black- White health disparities, extending beyond cardiovascular disease to include other conditions. Most of the conditions that have been associated with vitamin D deficiency also are more prevalent among African Americans. Examples include pre-eclampsia, asthma, diabetes, hypertension, kidney disease, and cancer, particularly colorectal cancer.(5;6) Low levels may even predict having a Cesarean section.(7)

The consequences of deficiency beginning in-utero are not fully known, but potentially substantial. Vitamin D is not a true a vitamin, but a pro hormone that directly or indirectly regulates over 200 genes.

It is not known whether potential developmental effects from early vitamin D deficiency would be reversed by high doses given late in life.

The American Academy of Pediatrics increased its recommended intake for infants, children, and adolescents to 400 IU vitamin D per day in effort to address the problem. While this amount will prevent rickets, it will not be enough to achieve presumed optimal levels for much of the population, particularly African Americans.

Resolving the question of the optimal dose of vitamin D for pregnant women, infants, children, and adults will be challenging, but the stakes are high, particularly for addressing health disparities.

An Institute of Medicine report on recommended vitamin D intake is expected out this year.

(1) Talwar SA, Aloia JF, Pollack S, Yeh JK. Dose response to vitamin D supplementation among postmenopausal African American women. Am J Clin Nutr 2007; 86(6):1657-1662.
(2) Mansbach JM, Ginde AA, Camargo CA, Jr. Serum 25-hydroxyvitamin D levels among US children aged 1 to 11 years: do children need more vitamin D? Pediatrics 2009; 124(5):1404-1410.
(3) Saintonge S, Bang H, Gerber LM. Implications of a new definition of vitamin D deficiency in a multiracial us adolescent population: the National Health and Nutrition Examination Survey III. Pediatrics 2009; 123(3):797-803.
(4) Moore CE, Murphy MM, Holick MF. Vitamin D intakes by children and adults in the United States differ among ethnic groups. J Nutr 2005; 135(10):2478-2485.
(5) Holick MF, Chen TC. Vitamin D deficiency: a worldwide problem with health consequences. Am J Clin Nutr 2008; 87(4):1080S-1086S.
(6) Grant WB. Epidemiology of disease risks in relation to vitamin D insufficiency. Prog Biophys Mole Biol 2006; 92(1):65-79.
(7) Merewood A, Mehta SD, Chen TC, Bauchner H, Holick MF. Association between vitamin D deficiency and primary cesarean section. J Clin Endocrinol Metab 2009; 94(3):940-945.

Competing interests:   None declared