Buffered or impaired: Maternal anemia, inflammation and breast milk macronutrients in northern Kenya.

BACKGROUND: Maternal anemia has adverse consequences for the mother-infant dyad. To evaluate whether and how milk nutrient content may change in ways that could "buffer" infants against the conditions underlying maternal anemia, this study assessed associations between milk macronutrients and maternal iron-deficiency anemia (IDA), non-iron-deficiency anemia (NIDA), and inflammation. METHODS: A secondary analysis of cross-sectional data and milk from northern Kenya was conducted (n = 204). The combination of hemoglobin and transferrin receptor defined IDA/NIDA. Elevated serum C-reactive protein defined acute inflammation. The effects of IDA, NIDA, and inflammation on milk macronutrients were evaluated in regression models. RESULTS: IDA (ß = 0.077, p = .022) and NIDA (ß = 0.083, p = .100) predicted higher total protein (ln). IDA (ß = -0.293, p = .002), NIDA (ß = -0.313, p = .047), and inflammation (ß = -0.269, p = .007) each predicted lower fat (ln); however, anemia accompanying inflammation predicted higher fat (ß = 0.655, p = .007 for IDA and ß = 0.468, p = .092 for NIDA). NIDA predicted higher lactose (ß = 1.020, p = .003). CONCLUSIONS: Milk macronutrient content both increases and decreases in the presence of maternal anemia and inflammation, suggesting a more complicated and dynamic change than simple impairment of nutrient delivery during maternal stress. Maternal fat delivery to milk may be impaired under anemia. Mothers may buffer infant nutrition against adverse conditions or poor maternal health by elevating milk protein (mothers with IDA/NIDA), lactose (mothers with NIDA), or fat (mothers with anemia and inflammation). This study demonstrates the foundational importance of maternal micronutrient health and inflammation or infection for advancing the ecological understanding of human milk nutrient variation.

Variation in breast milk macronutrient contents by maternal anemia and hemoglobin concentration in northern Kenya.

OBJECTIVES: This study explored differing levels of macronutrients in breast milk in relation to maternal anemia and hemoglobin. METHODS: Archived milk specimens and data from a cross-sectional sample of 208 breastfeeding mothers in northern Kenya, originally collected in 2006, were analyzed; data included milk fat, maternal hemoglobin concentration, and anemia status (anemia defined as hemoglobin <12 g/dL). Total protein and lactose were measured and energy was calculated. To explore the association between milk outcomes (fat, protein, lactose, and energy) and anemia, regression models were constructed with and without adjustment for maternal age, parity, and time (days) postpartum. The same models were constructed using hemoglobin as a continuous predictor in lieu of dichotomous anemia to explore the role of hemoglobin levels and anemia severity in predicting milk outcomes. RESULTS: The group comparison indicated significantly higher milk protein and lower milk fat for anemic mothers relative to nonanemic counterparts. After adjustment for maternal age, parity, and time postpartum, maternal anemia was associated with significantly higher milk protein (P = 0.001) and significantly lower milk fat (P = 0.025). Hemoglobin had a significant inverse relationship with milk protein (P = 0.017) and a marginally significant positive relationship with milk fat (P = 0.060) after adjusting for the maternal variables. Neither anemia nor hemoglobin was significant in predicting lactose or milk energy. CONCLUSIONS: Maternal anemia and hemoglobin concentration may be associated with complex changes in milk macronutrients. Future research should clarify the impact of maternal anemia on a range of breast milk components while accounting for other maternal characteristics.