Milk composition in women from five different regions of China: the great diversity of milk fatty acids.

Human milk samples were obtained from 146 lactating women living in five distinct geographic regions of the People's Republic of China. The regions were characterized as follows: pastoral, rural, urban 1, urban 2, and marine. Dietary information obtained on a subsample of women providing milk suggested distinct differences in the food availability in the five regions and the habitual diets of the lactating women studied. The milk concentration of docosahexaenoic acid (DHA) varied greatly (g/100 g total fatty acids): 0.44 +/- 0.29 (pastoral), 0.68 +/- 0.29 (rural), 0.88 +/- 0.34 (urban 1), 0.82 +/- 0.35 (urban 2), and 2.78 +/- 1.20 (marine region). Docosahexaenoic acid is critical for brain and retina development in the infant. Milk arachidonic acid (AA) ranged from 0.80 +/- 0.14 (rural) to 1.17 +/- 0.33 and 1.22 +/- 0.32 g/100 g fatty acids from the marine and pastoral regions. Arachidonic acid is associated with infant growth. The AA to DHA ratio (g/g) was highly variable also: 2.77 (pastoral), 1.18 (rural), 1.01 (urban 1), 1.23 (urban 2), and 0.42 (marine). The DHA concentration found in the milk of women from the marine region was twice as high as any reported previously, but was in a range similar to the amounts found in the milk of women fed fish oil. Seafood consumption by the women residing in the marine region is a likely contributor to the DHA concentration in their milk. These data illustrate the heterogeneity of the fatty acid composition of human milk and suggest a great influence of geography and the maternal diet on concentrations of DHA and AA in human milk.