Advancing understanding of racial and ethnic disparities in folic acid supplementation via national institutes of health all of US data

• Non-Hispanic Black women had higher odds of folic acid supplementation compared to non-Hispanic White women. • Across all racial/ethnic groups examined, uninsured women had lower folic acid supplementation rates. • Pregnancy and older age were associated with higher odds of folic acid supplementation Neural tube defects (NTDs) are congenital anomalies caused by failure of neural tube closure during pregnancy and contribute to childhood morbidity and mortality. Folic acid supplementation reduces NTDs risk, yet adherence remains low, particularly among Hispanic women and non-Hispanic Black women. This study examines folic acid supplementation by race/ethnicity, nativity, and social determinants of health (SDOH). Methods: Data came from the National Institutes of Health All of Us Research Program (Registered Tier Dataset v7), a large, diverse biomedical dataset that includes underrepresented populations. Analyses were restricted to participants enrolled between May 2018-June 2022. Adjusted multivariable logistic regression models assessed for differences in folic acid supplementation, controlling for age, income, education, insurance, and pregnancy. Results: Among pregnant and non-pregnant women of childbearing age (18–49 years; N = 85,874), older age was associated with higher odds of folic acid supplementation (aOR = 1.04, 95% CI: 1.03–1.04, p < 0.001). Lack of insurance was associated with lower odds of supplementation (aOR = 0.44, 95% CI: 0.34–0.56, p 0 < 0.001), while pregnancy was associated with higher odds (aOR = 2.27, 95% CI: 1.90–2.71, p < 0.001). Non-Hispanic Black women had higher odds compared to non-Hispanic White women (aOR = 2.13, 95% CI: 1.88–2.40, p < 0.001). Among Hispanic women, age and pregnancy were associated with higher odds, lack of insurance with lower odds, and nativity was not associated with supplementation. Conclusion: These findings highlight the role of SDOH and the need for equitable interventions across the reproductive lifespan.