McKibben RA, Zhao D, Lutsey PL, et al. Factors associated with change in 25-hydroxyvitamin D levels over longitudinal followup in the ARIC study. The Journal of Clinical Endocrinology & Metabolism. http://press.endocrine.org/doi/abs/10.1210/jc.2015-1711 Context: A single measurement of 25-hydroxyvitamin D [25(OH)D] may not accurately reflect long-term vitamin D status. Little is known about change in 25(OH)D levels over time, particularly among blacks. Objective: To determine longitudinal changes in 25(OH)D levels among Atherosclerosis Risk in Communities (ARIC) study participants. Design: Longitudinal study. Setting: General community. Participants: 9890 white and 3222 black participants at visit 2 (1990–1992), 888 whites and 876 blacks at visit 3 (1993–1994), and 472 blacks at the brain visit (2004–2006). Main Outcome Measure: 25(OH)D levels were measured, and regression models were used to assess associations between clinical factors and longitudinal changes in 25(OH)D. Results: Vitamin D deficiency [<50 nmol/L (<20 ng/ml)] was seen in 23% and 25% of whites at visits 2 and 3, and in 61%, 70%, and 47% of blacks at visits 2, 3, and the brain visit, respectively. 25(OH)D levels were correlated between visits 2 and 3 (3–year interval) among whites (r=0.73) and blacks (r=0.66). Among blacks, the correlation between visit 2 and brain visit (14-year interval) was 0.33. Overall, increasing 25(OH)D levels over time were associated with male gender, use of vitamin D supplements, greater physical activity, and higher HDL-C (p<0.001). Decreases in 25(OH)D levels over time were associated with current smoking, higher body mass index, higher education, diabetes, and hypertension (all p<0.05). Conclusions: Among U.S. blacks and whites, 25(OH)D levels remained relatively stable over time. Certain modifiable lifestyle factors were associated with change in 25(OH)D levels over time.