Prevalence of low vitamin D levels among older US Asian and Pacific Islander adults

While US Asian and Pacific Islander adults have lower 25-hydroxyvitamin D (25(OH)D) levels than White adults, ethnic subgroup data remain limited. In a large California population, the adjusted prevalence of 25(OH)D < 20 ng/mL (50 nmol/L) was 1.5- to 2.7-fold higher for Asian/Pacific Islander compared to White adults, with substantial variation by ethnicity. Purpose: US Asian and Pacific Islander (PI) adults generally have lower 25-hydroxyvitamin D [25(OH)D] levels than non-Hispanic White (NHW) adults, but subgroup data remain limited. We compared sex- and ethnicity-specific prevalence of low 25(OH)D among older Asian/PI and NHW adults. Methods: Data from 102,556 Asian/PI and 381,724 NHW adults aged 50-89 years with measured 25(OH)D in 2012-2019 and body mass index (BMI, within +/- 1 year) were examined in a California healthcare system. Low 25(OH)D < 20 ng/mL (50 nmol/L) was examined by race and ethnicity. Covariates included age, smoking, BMI, and season of measurement. Modified Poisson regression was used to estimate prevalence ratios (aPR), adjusting for covariates. Results: Among 31,287 Asian/PI men and 71,269 Asian/PI women, the prevalence of low 25(OH)D was 22.6% and 14.7%, respectively, significantly higher than observed for 122,162 NHW men (12.3%) and 259,562 NHW women (9.9%). Within Asian/PI subgroups, low 25(OH)D prevalence ranged from 17 to 18% (Korean, Japanese, Filipino), 22 to 24% (Chinese, Vietnamese), 28% (South Asian), and 35% (Native Hawaiian/PI) among men and 11 to 14% (Japanese, Filipina, Chinese, Korean), 17 to 18% (South Asian, Vietnamese), and 26% (Native Hawaiian/PI) among women. The corresponding aPRs (NHW reference) for men and women were as follows: Native Hawaiian/PI, 2.70 and 2.34; South Asian, 2.56 and 2.07; Vietnamese, 2.17 and 2.31; Chinese, 2.04 and 1.89; Korean, 1.60 and 1.85; Filipino, 1.58 and 1.52; and Japanese, 1.58 and 1.49 (p < 0.001). Conclusion: In a large US healthcare population of older Asian/PI adults, low 25(OH)D prevalence was 1.5- to 2.7-fold higher for Asian/PI compared to NHW adults, with substantial variation by sex and ethnicity.