Quantification of breast milk trans fatty acids and trans fat intake by Hong Kong lactating women.

Background/objectives: Diet westernization in Hong Kong may increase trans fat intake, whereas it may decrease intake of polyunsaturated fatty acids. The present study was to determine the current breast milk fatty acid composition and trans fat intake by Hong Kong lactating mothers.

Methods: Sixty lactating women were recruited for the study. Each participant donated 15 ml of milk at week 4 and 6 after delivery. Dietary data were collected using a 3-day food record method, covering 2 weekdays and 1 weekend day. Milk fatty acids were analyzed using a gas chromatography method. Trans fat consumption was assessed using the Nutrition Data System for Research or calculating the intake based on percentage of trans fatty acids in the breast milk.

Results: Linoleic acid, α-linolenic acid, arachidonic acid, and docosahexaenoic acid in breast milk were 16.23%, 1.52%, 0.59%, and 0.66% total milk lipids, respectively. Mean daily intakes of total fat, saturated fatty acids, monounsaturated fatty acids, were 79, 24, 29, and 18 g, respectively. Total trans fat intake was estimated to be 1.15-1.20 g daily and accounted for 0.50-0.52% total energy.

Conclusions: Breast milk of Hong Kong Chinese lactating women contained relatively higher contents of arachidonic and docosahexaenoic acids compared with those of Western countries. Compared with the previous study conducted in 1995, breast milk total trans fatty acids in 2018 still remained low. Total trans fat intake by Hong Kong lactating women in 2018 was a half of WHO's recommendation that total trans fat intake should be <1% total energy.