Folic acid is most important before many people realize they are pregnant. That makes access to supplements, fortified foods and reliable health information especially important for anyone who could become pregnant.
A new observational study of more than 85,000 women ages 18 to 49 found that insurance coverage and access to health care were linked to whether participants reported taking folic acid supplements. The study did not measure total folic acid intake or track birth defects. It also cannot prove that insurance coverage alone caused differences in supplement use. But the findings highlight a persistent gap between a well-established nutrition recommendation and the real-world barriers that can make it harder to follow.
Folic acid is a form of folate, a B vitamin the body uses to make new cells. Getting enough folic acid before and during early pregnancy can help prevent neural tube defects, serious birth defects affecting the baby’s brain and spine. These include spina bifida and anencephaly.
The timing matters because the neural tube develops very early in pregnancy, often before someone knows they are pregnant.
The study, published in the journal Sexual & Reproductive Healthcare, analyzed data from the National Institutes of Health’s All of Us Research Program. Researchers examined self-reported folic acid supplementation among women across the United States and explored how use varied based on factors such as age, pregnancy, education, income, race, ethnicity and insurance status.
Women without health insurance were significantly less likely to report taking folic acid supplements. Pregnant women and older participants were more likely to report supplementation, which may reflect greater contact with health care providers and prenatal services.
“Preventing neural tube defects begins long before pregnancy, which is why access to healthcare and preventive education is so important for all women of reproductive age,” said Yael Marks, a health sciences assistant clinical professor at the University of California, Irvine School of Pharmacy & Pharmaceutical Sciences and the study’s corresponding author.
The researchers also examined racial and ethnic differences. Non-Hispanic Black women were more likely than non-Hispanic white women to report taking supplements. Among Hispanic participants, birthplace was not significantly associated with folic acid supplementation. Age, pregnancy, educational attainment and insurance coverage were more closely linked to supplement use within that group.
The findings point to the role of structural barriers, not simply individual choices.
A daily vitamin may sound like a straightforward solution. But people without insurance or regular access to health care may be less likely to receive preventive guidance before pregnancy. Cost, competing priorities and inconsistent access to supplements may also play a role.
The study cannot show how much folic acid each participant consumed. Some people who did not report taking a supplement may have received folic acid from fortified foods. Others may have reported supplement use without taking a vitamin consistently or consuming the recommended amount.
That distinction is important because folic acid can come from more than one source.
U.S. guidance recommends that women capable of becoming pregnant get 400 micrograms of folic acid daily. Supplements and fortified foods can help people reach that amount. Folic acid is added to many enriched breads, flours, pastas, rice products, breakfast cereals and some corn masa flour products.
Naturally folate-rich foods, including beans, leafy greens, asparagus, citrus fruits and avocados, are also valuable parts of a balanced diet. But naturally occurring folate and added folic acid are not interchangeable when it comes to birth-defect prevention. Folic acid is the form with established evidence for reducing neural tube defects.
Food fortification can help close some of the gaps left by supplements alone.
The United States has required folic acid fortification of certain enriched grain products since the late 1990s. But corn masa flour, used to make foods such as tortillas and tamales, was not included in the original federal requirement.
In 2016, the U.S. Food and Drug Administration allowed manufacturers to voluntarily add folic acid to corn masa flour. Uptake remained limited. California has now gone further.
A California law that took effect Jan. 1, 2026, requires many corn masa flour and wet corn masa products sold in the state to include folic acid. The law also requires the added folic acid to be declared on the nutrition label. The goal is to make the nutrient more accessible through foods commonly eaten in many households, including Hispanic and Latino households.
The new study did not evaluate the California policy. Its participant data were collected before the law took effect. But the policy illustrates why public-health strategies often need to extend beyond telling people to take a supplement.
Education still matters. So does access.
People who are pregnant, planning a pregnancy or unsure whether they are getting enough folic acid should speak with a health care provider. Some individuals may need different guidance based on their medical history.
The study used participant data from the National Institutes of Health’s All of Us Research Program. The research also received support from a University of California, Irvine Genetic Epidemiology Research Institute grant awarded to the co-first authors and from the UCI All of Us Research Program in collaboration with multiple university departments, including the dean’s office of the UCI School of Medicine.