A study of more than 85,000 American women has found a stark divide in folic acid supplementation—one driven not by awareness or intention, but by whether women can actually access health care and afford insurance. Researchers at UC Irvine, using data from the National Institutes of Health's All of Us Research Program, discovered that structural barriers like insurance coverage and health care access play a far larger role in preventing neural tube defects than birthplace or cultural background alone.
Neural tube defects such as spina bifida and anencephaly develop early in pregnancy—often before a woman knows she is pregnant—and folic acid, a form of vitamin B, is proven to prevent them. National guidelines recommend daily folic acid supplementation for all women of reproductive age, yet the study found overall use remains stubbornly low. The gap is not distributed equally across the population.
Women without health insurance were significantly less likely to report taking folic acid supplements, the researchers found. Older pregnant women, by contrast, were more likely to use them—a pattern researchers attributed to greater access to health care providers and prenatal care. Age itself mattered less than the opportunity to see a doctor.
The racial and ethnic findings challenged some assumptions. Non-Hispanic Black women were more likely than non-Hispanic White women to report taking folic acid supplements. Among Hispanic participants, U.S.-born and foreign-born women showed no significant difference in supplementation rates. Instead, age, being pregnant, educational attainment, and insurance coverage shaped who took supplements within this group. The data suggests that health care access, not where someone was born or their cultural background, determines whether they can act on prevention guidelines.
The interdisciplinary team—drawing together researchers from UC Irvine's School of Pharmacy & Pharmaceutical Sciences, the Department of Chicano/Latino Studies, and the Department of Psychology—approached the question from multiple angles. Yael Marks, the study's corresponding author and a health sciences assistant clinical professor in the School of Pharmacy & Pharmaceutical Sciences, emphasized what the findings mean for prevention: "Preventing neural tube defects begins long before pregnancy, which is why access to health care and preventive education is so important for all women of reproductive age. Our findings show that structural barriers like insurance coverage can strongly influence whether women receive this simple but lifesaving intervention."
Isabel Almeida, a co-author from the Department of Chicano/Latino Studies and Department of Psychology, noted that the collaboration expanded how the team understood the problem. "This collaboration allowed us to examine folic acid supplementation not only as a medical issue, but also through the lens of social inequities and health care access. Bringing together researchers from different disciplines helps us better understand the barriers communities face and identify more effective public health solutions."
The timing of these findings is significant. In January 2026, California became the first state to require folic acid fortification of corn masa flour products—including tortillas—a dietary staple for many Hispanic households. The UC Irvine research supports such efforts by showing that addressing structural health care barriers works alongside, and perhaps more effectively than, relying on individual supplementation. When prevention is woven into the food supply rather than dependent on access to doctors and insurance, more women and their future children benefit.