Abstract
Background: Vitamin D deficiency (VDD) may be associated with chronic health issues, including markers of liver disease; however, evidence in American Indian adolescents is limited. Therefore, we aimed to evaluate the relationship between VDD in American Indian adolescents and markers of liver disease, including both serum and magnetic resonance imaging (MRI) markers. Methods: The Strong Heart Family Study (SHFS) is a multicenter, family-based, prospective cohort study among American Indians. We evaluated SHFS participants who were <20 years old at baseline (2001-2003; n = 308), defined VDD as hydroxyvitamin-D (25[OH]D) ≤ 20 ng/mL and calculated the Hepatic Steatosis Index (HSI). In 2006-2009, we measured follow-up serum markers (n = 269, median follow-up = 5.8 years, range = 3.0-8.5), and in 2018-2020, we collected MRI markers of hepatic steatosis and fibrosis (n = 33, median follow-up = 16.7 years, range = 15.3-18.1). Results: At baseline, a greater proportion of those with VDD had HSI > 36 (64.5% with VDD; p = 0.002). For participants who reported consuming alcohol, serum alkaline phosphate (ALP) increased at follow-up, which was higher for those with versus without VDD (beta = 12.24, 95% CI = 1.23-23.24). For participants who reported not consuming alcohol, ALP decreased but was not different between the VDD groups. The MRI-proton density fat fraction was higher in those with (median = 11.0%, IQR = 7.7-19.2%) versus without (median = 4.4, IQR = 1.8-6.3%) VDD at baseline (p < 0.001). Conclusions: VDD may be associated with markers of liver disease in American Indian adolescents. After 5.5 years, VDD was associated with increasing ALP in those who consume alcohol, while controlling for adiposity and other covariates. After 17 years of follow-up, VDD was associated with increased liver MRI-PDFF.