Breast Milk Vitamin C Concentrations and Their Association With Confinement Dietary Practices in the Early Postpartum Period

Vitamin C is a potent antioxidant that supports both short- and long-term health in infants. As breast milk is the main source of vitamin C for infants, maternal postpartum dietary practices may influence vitamin C concentrations in breast milk and thereby affect infant intake. This study aimed to examine the trend of vitamin C levels in breast milk during the postpartum confinement period in Malaysian mothers and their association with maternal dietary intake. It was designed as a longitudinal observational study using data from a randomised controlled trial investigating relaxation therapy. Sixty-four first-time mothers in the Klang Valley participated. Breast milk samples were collected during home visits at week 2 and weeks 8-12 postpartum. Vitamin C content in breast milk was measured using high-performance liquid chromatography. Participants completed a questionnaire covering sociodemographic characteristics and traditional postpartum practices, including a food list that assessed changes in dietary intake (classified as avoided, reduced, maintained, or increased) at two weeks postpartum. The mean vitamin C concentration in breast milk was 3.87 ± 2.8 µg/mL, which was lower than values commonly reported in other populations. A significant positive correlation was observed between vitamin C concentrations at the early and later time points (r=0.60, p=0.022). However, vitamin C levels were significantly lower at week 2 than at weeks 8-12 (p=0.04). At 2 weeks postpartum, fruit intake remained largely unchanged, whereas eggs and nuts were the most frequently avoided foods. Conversely, fish and vegetable consumption increased the most. Fruit intake correlated with vitamin C at week 2 (r=0.573, p=0.01), but not later, and vitamin C was not associated with other food categories (p>0.05). These findings highlight the importance of adequate intake of vitamin C-rich foods (e.g., fruits) during confinement to support breast milk levels, reinforcing the importance of culturally sensitive dietary guidance in maternal care. Nevertheless, generalizability may be limited because participants were predominantly educated urban Malay mothers.