Racial & Ethnic Disparities in Infant Mortality... a vitamin D problem?
Vitamin D & Race
Webinar
William B. Grant, PhD
Sunlight, Nutrition and Health Research Center
February 2013
Dr. William Grant is an epidemiologist and founder of the nonprofit organization Sunlight, Nutrition and Health Research Center (SUNARC). Grant holds a PhD in Physics from UC Berkeley and worked as a senior research scientist in the field of optical and laser remote sensing of the atmosphere and atmospheric sciences at SRI International, the Jet Propulsion Laboratory, and the NASA Langley Research Center. His career included pioneering development of laser remote sensing instrumentation, while the latter half included participating on many NASA-led airborne atmospheric chemistry field missions to the far corners of the world. Since 2000, he has focused on ultraviolet-B (UVB) radiation and vitamin D and their relation to cancer and other diseases. He has written over 140 peer-reviewed articles and editorials on vitamin D and health, edited two books, and contributed half a dozen chapters to other books.
What is the cause of black-white disparities in infant mortality rates?
Hauck et al., in their paper
Racial and ethnic disparities in infant mortality, cited that black infants are 2.5 times more likely to die than white infants. MacDoman et al. cite this elevated mortality is due to higher preterm birth rates in non-Hispanic blacks. Grant cites that preterm birth and low birth weight are very closely related. Being born small and early are both risk factors for infant mortality.
Effects of vitamin D deficiency during pregnancy
Low vitamin D levels during pregnancy are associated with increased risk of preterm birth and low birth weight and factors linked to gestational diabetes, preeclampsia, and bacterial vaginosis.
A study by Zhang et al. concluded that pregnant women with lower vitamin D levels had a greater risk of gestational diabetes, even to the point of every drop of 5 ng/ml was related to an increase of 30% in gestational diabetes risk.
A study by Bodnar et al. showed as vitamin D levels increase from low to high, the risk of preeclampsia decreases. Since the time of this webinar a new study by Mirzakhani et al. found that women who had vitamin D levels above 40 ng/ml at conception had virtually no preeclampsia.
An ongoing field trial at the Medical University of South Carolina has been running for over a year. More than 3000 women in this predominantly black community had their vitamin D levels tested at their first prenatal visit and were given supplements and information on the importance of having a vitamin D level of at least 40 ng/ml. Pregnancy outcomes including gestational diabetes, preeclampsia and preterm birth have been measured and preliminary results will be reported in the coming months.
Differences in vitamin D levels between black and white women
Grant shows vitamin D levels collected in the National Health and Nutrition Examination Survey (NHANES) from 2004-2008. Black women had an average of 14 ng/ml, and white women had double that amount, 28 ng/ml. Since then GrassrootsHealth has reported on the new NHANES data and the most compelling chart shows that almost all black women are below the recommended 40 ng/ml (100 nmol/L).
Alternate explanations?
Other maternal risk factors for infant mortality include smoking, obesity, exposure to outdoor air pollution, having had 2 or more previous pre-term births, low water intake, and heavy alcohol or cocaine use. Grant notes that obesity seems to be a more important risk factor for whites than blacks.
Recommendations
Vitamin D deficiency is a significant risk factor for pregnancy outcomes and is more common in dark skinned ethnic groups.
Based on the randomized controlled trial by Hollis et al., we recommend all pregnant women test and raise vitamin D levels to at least 40 ng/ml. For most women, this requires vitamin D supplementation of approximately 4,000-5,000 IU/day.
