The effectiveness of daily supplementation with 400 or 800 µg/day folate in reaching protective red blood folate concentrations in non-pregnant women: a randomized trial

Purpose Folate required to achieve desirable red blood cell (RBC) folate concentrations within 4–8 weeks pre-pregnancy is not known. We studied the effect of supplementation with 400 or 800 µg/day folate in achieving RBC-folate ≥906 nmol/L.