Evidence of vitamin A deficiency during lactation is required to inform policy. This cross-sectional study assessed vitamin A status in lactating Thai women by measuring total body stores (TBS), serum and breast milk retinol, and dietary intake.
Ninety-four women at 6-8 weeks postpartum, residing in semi-rural (Ayutthaya) and urban (Bangkok) areas were enrolled. TBS of vitamin A were measured by C-retinol isotope dilution technique, and used further to calculate total liver reserves (TLR). Serum and casual milk samples were analyzed for retinol content via HPLC. Dietary vitamin A intake was assessed by food frequency questionnaire (FFQ) and 24-hour dietary recalls for 3 days.
Median vitamin A intakes were approximately half of daily recommended levels with the majority being from animal sources. Considering TLR as 50% TBS, 20% and 11% of lactating mothers in Ayutthaya and Bangkok, showed depleted reserves (< 0.1µmol retinol/g liver). For both groups, serum retinol (1.58, 1.52 µmol/L) and breast milk retinol (1.89, 1.74 µmol/L) were within normal range. Lactating women in both areas with depleted TLR showed low breast milk retinol (<1.05 µmol/L) and consumed less dietary vitamin A, especially from animal foods. Breast milk retinol demonstrated strong correlation with TBS and TLR. Using the receiver operator characteristics (ROC) analysis, the predictability of breast milk retinol for liver reserves confirms the validity of the current cut-off value of 1.05 µmol/L.
In conclusion, approximately 15% of lactating women had depleted stores and breast milk retinol shows potentials to screen for at risk mothers.