Objective: The objective was to investigate changes in milk composition that reflect variations
in breast permeability, milk synthesis, and immune response in women before, during,
and after mastitis
Methods: Mothers (n = 26) were followed prospectively from day 5 postpartum to the end
of their lactation. Milk from each breast, blood, 24-hour urine samples, and data on breast
and systemic pathologies were collected at reference intervals during the first 3 months postpartum,
daily during the occurrence of any breast inflammation, and 7 days after resolution
of symptoms, and was analyzed using mixed-model analysis (repeated measures).
Results: There was a significant difference in sodium (p < 0.001), chloride (p < 0.001), serum
albumin (p < 0.02) and lactose (p < 0.003) in the breast with mastitis when compared with
both the contralateral asymptomatic breast and "healthy" breasts. Inflammation of the whole
breast was a significant predictor for a decreased glucose (p < 0.01) and hyperacute systemic
symptoms predicted a decrease in milk glucose (p < 0.03) and an increased lactoferrin (p <
0.05) and sIgA (p < 0.03).
Conclusions: There is an increased breast permeability, reduced milk synthesis, and increased
concentration of the immune components sIgA and lactoferrin with increasing severity
of breast and systemic symptoms. The changes observed in milk composition during periods
of increased breast permeability cannot be solely explained by the current theory of
permeability of the paracellular pathway and further research in this area is required.
