Summary

Background: Human milk produced during prolonged lactation (> 1 year) is extraordinarily rich in fat and has a higher energy content than human milk produced during short lactation.
Objectives: To estimate the fatty acid (FA) profile of human milk and to test the hypothesis that the proportion of C12 and C14 (two dietary saturated FA known to most promote hypercholesterolemia) in human milk during prolonged lactation is similar to that in short lactation.
Methods: We conducted a cross-sectional study of 30 mothers of term infants lactating for more than 1 year as compared with 25 mothers of full-term infants who lactated for 2–6 months. Milk was collected by manual expression in mid-breastfeeding.
Results: The two groups did not differ in maternal height, weight, body mass index, diet, infant birth weight and gestational age, but mothers in the prolonged lactation group were significantly older. There was a significant correlation between lactation duration and C12 or C14. The percentage of all FA combined (except for C12 and C14) decreased significantly over time. In contrast, C12:0 and C14:0 combined increased significantly during lactation (R2 = 10.0%, P < 0.03).
Conclusions: Women who lactated for more than 1 year had higher C12 and C14 FA percentages in their milk than women who lactated for 2–6 months.