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Absorption of Folic Acid from a Softgel Capsule Compared to a Standard Tablet

Maki, Kevin C., Ndife, Louis I., Kelley, Kathleen M., Lawless, Andrea L., Brooks, James R., Wright, Shannon B., Shields, Jocelyn M., Dicklin, Mary R.
Journal of the Academy of Nutrition and Dietetics 2012 v.112 no.7 pp. 1062-1067
analysis of variance, bioavailability, blood serum, breakfast, cross-over studies, diet, fetal development, folic acid, fortified foods, neural tube defects, premenopause, risk, women
Consumption of 400 μg folic acid per day from fortified foods and/or supplements, plus food folate from a varied diet is recommended for women of childbearing potential to reduce the risk for neural tube defects during fetal development. This randomized crossover study was designed to evaluate the bioavailability of folic acid from a multivitamin softgel capsule vs a folic acid tablet in 16 premenopausal women (18 to 45 years of age). Participants were randomly assigned to receive a single dose of ∼1,000 μg folic acid in two tablets or ∼1,000 μg folic acid in a multivitamin softgel capsule, and then crossed over to receive the other study product ∼1 week later. Products were administered with a low-folate breakfast. Blood samples were collected predose (0 hour) and 1, 2, 3, 4, 6, and 8 hours post-dose for serum folate analysis. Repeated measures analysis of variance was used to compare responses between treatments. Data from the two sequence groups (n=8 per sequence) were pooled. Mean serum folate total and net incremental areas under the curve (AUC₀₋₈ ₕₒᵤᵣₛ) were not significantly different between tablets and softgel capsule (AUC₀₋₈ ₕₒᵤᵣₛ 214.9±11.2 hours×ng/mL [487±25.4 hours×nmol/L] and 191.6±13.3 hours×ng/mL [434.2±30.1 hours×nmol/L]; net incremental AUC₀₋₈ ₕₒᵤᵣₛ 117.3±8.5 hours×ng/mL [265.8±19.3 hours×nmol/L] and 105.8±12.5 hours×ng/mL [239.7±28.3 hours×nmol/L], respectively), nor was maximum folate concentration (45.1±2.5 ng/mL [102.2±5.7 nmol/L] and 42.5±3.8 ng/mL [96.3±8.6 nmol/L], respectively). Time to peak folate concentration was significantly (P<0.001) delayed for the softgel capsule vs tablet (3.9±0.3 vs 1.7±0.2 hours, respectively). In conclusion, apparent bioavailability of folic acid was similar for the folic acid tablets and a multivitamin softgel capsule.