The availability of data on plasma vitamin D (25(OH)D) concentrations in the last two rounds of the National Health and Nutrition Examination Survey has generated a high level of interest in the consequences of 25(OH)D deficiency and in particular its potential impact on black Americans. Fundamental new questions about the biology of vitamin D have now come to the fore. Are low 25(OH)D-intact parathyroid hormone (iPTH) levels a physiologic """"""""abnormality"""""""" in African Americans or does the 25(OH)D-iPTH system have sufficient plasticity to adapt to low sunlight exposure? Could the low 25(OH)D levels which result from the """"""""gene- environment discordance"""""""" observed in dark skinned populations in the US be a risk factor for metabolic disorders? Ultimately, the public health community and regulatory bodies must offer recommendations for optimal levels and supplementation. We propose to utilize cohorts from an ongoing NIH-funded study designed to identify determinants of weight change and cardiovascular disease risk in five Afro-origin populations [Modeling the Epidemiologic Transition Study (METS)] to examine these questions. The five METS countries include Ghana, Seychelles, South Africa, Jamaica and the US;the five populations differ greatly in terms of sun exposure and dietary intakes. In addition to the extensive energy expenditure, dietary intake and obesity-related metabolic markers being measured in METS, we propose to assess plasma 25(OH)D, iPTH, serum and urinary calcium, as well as bone mineral density and body composition using dual x-ray absorptiometry. The associations of adiposity, weight change, CVD risk factors such as blood pressure and insulin, and bone mineral density with 25(OH)D and iPTH will be assessed. The proposed study will provide a comprehensive assessment of the distribution and determinants of 25(OH)D-iPTH and related physiologic measures across a wide range of latitude and lifestyles. These data should contribute substantially to our understanding of the """"""""normal"""""""" range within which these hormones function and their significance in Afro-origin populations.
Fundamental questions about the biology of vitamin D and the consequences of deficiency, particularly in reference to black populations, have recently generated a high degree of interest. The proposed project will examine associations of circulating levels of vitamin D and parathyroid hormone with adiposity, weight change and cardiovascular disease risk factors in five populations of African origin living across a wide range of latitudes and lifestyles in order to determine need for vitamin D supplementation.
|Dugas, Lara R; Bernabé, Beatriz Peñalver; Priyadarshini, Medha et al. (2018) Decreased microbial co-occurrence network stability and SCFA receptor level correlates with obesity in African-origin women. Sci Rep 8:17135|
|Durazo-Arvizu, Ramón A; Dawson-Hughes, Bess; Kramer, Holly et al. (2017) The Reverse J-Shaped Association Between Serum Total 25-Hydroxyvitamin D Concentration and All-Cause Mortality: The Impact of Assay Standardization. Am J Epidemiol 185:720-726|
|McGrath, Sean; Brazel, Danielle; Dugas, Lara et al. (2017) Physical activity and central adiposity in a cohort of African-American adults. BMC Obes 4:34|
|Chiang, Daniel; Kramer, Holly; Luke, Amy et al. (2017) 25-Hydroxyvitamin D and blood pressure: a plateau effect in adults with African ancestry living at different latitudes. J Hypertens 35:968-974|
|Kramer, Holly; Camacho, Pauline; Aloia, John et al. (2016) ASSOCIATION BETWEEN 25-HYDROXYVITAMIN D AND INTACT PARATHYROID HORMONE LEVELS ACROSS LATITUDE AMONG ADULTS WITH AFRICAN ANCESTRY. Endocr Pract 22:911-9|
|Yuen, Shennin N; Kramer, Holly; Luke, Amy et al. (2016) Fibroblast Growth Factor-23 (FGF-23) Levels Differ Across Populations by Degree of Industrialization. J Clin Endocrinol Metab 101:2246-53|
|Tayo, Bamidele O; Akingbola, Titilola S; Salako, Babatunde L et al. (2014) Vitamin D levels are low in adult patients with sickle cell disease in Jamaica and West Africa. BMC Hematol 14:12|
|Durazo-Arvizu, Ramon A; Camacho, Pauline; Bovet, Pascal et al. (2014) 25-Hydroxyvitamin D in African-origin populations at varying latitudes challenges the construct of a physiologic norm. Am J Clin Nutr 100:908-14|
|Mora, N; Rieke, K; Plitcha, J et al. (2013) 25-Hydroxyvitamin D Supplementation and BMI Change: A Meta-Analysis of Randomized Controlled Trials. J Obes Weight Loss Ther 3:181|
|Durazo-Arvizu, Ramon A; Aloia, John F; Dugas, Lara R et al. (2013) 25-hydroxyvitamin D levels in African American and Nigerian women. Am J Hum Biol 25:560-2|
Showing the most recent 10 out of 11 publications