Folic acid fortification is associated with reduced risk of neural tube defects (NTDs). Since vitamin B12 affects the metabolism of red blood cell (RBC) folate, fortification with vitamin B12 may complement folic acid fortification to reduce the risk of NTDs. We studied the association between vitamin B12 status and RBC folate insufficiency (<906 nmol/L) in Belize because it is a population at high risk for NTDs.
In 2011, a national probability-based survey was completed among Belizean non-pregnant women of childbearing-age (WCBA), 15-49 years. Socio-demographic and health information, and blood samples for RBC folate and vitamin B12 were collected from 937 women. RBC folate and vitamin B12 were measured by microbiologic assay. Adjusted geometric means (adjGM) were estimated for RBC folate and vitamin B12, and trend analysis was performed on RBC folate concentrations by vitamin B12 status.
National adjGM and 95% CI for RBC folate and vitamin B12 were 719 nmol/L (689, 750) and 233 (223, 244), respectively. RBC folate concentrations were lowest among Mayans and Garifunas/Creoles. In multivariate analyses, RBC folate adjGM increased (p for trend <0.001) from 632 nmol/L among vitamin B12 deficient WCBA to 641 among vitamin B12 marginally deficient WCBA to 794 nmol/l among WCBA with normal vitamin B12 status. Similar trends were observed when stratifying by various socio-demographic characteristics.
RBC folate concentrations were associated with a positive linear trend with vitamin B12 status in Belize. Countries with a high prevalence of vitamin B12 deficiency might consider the potential impact of joint folic acid and vitamin B12 fortification for reducing NTD risk.