Breast milk macro- and micronutrient composition in lactating mothers from suburban and urban Shanghai

The objective of this study was to measure and compare the macro- and micronutrient composition of breast milk in urban and suburban lactating mothers living in Shanghai, China.

Primiparous women residing in three urban regions (n= 30/region) and a suburban area of Shanghai (n= 30) were recruited. Breast milk samples were collected 8-10 days postpartum and dietary intake was determined.

Women from the suburban area were of lower socio-economic status as indicated by levels of education, occupation and income. With the exception of carbohydrates, mothers in all urban areas had significantly higher macronutrient intake levels than suburban area mothers. Sodium, potassium, phosphorus and calcium intake levels were significantly lower in suburban compared to all urban women. Concentrations of protein, lipids, copper, sodium, potassium, chlorine, zinc, manganese, phosphorus and iron were all significantly lower in milk obtained from suburban compared to urban women. Concentrations of carbohydrates in milk from suburban women were significantly higher than concentrations in than two of the three urban groups. Offspring from women in Chongming county gained significantly less weight between birth and 6 months than did offspring born to women from the three other counties.

In summary, there were significant differences in macro- and micronutrient intake levels and breast milk concentrations between women from urban and suburban Shanghai. These differences may have important implications for the growth and development of breastfed infants.