Mandatory trans fat labeling regulations and nationwide product reformulations to reduce trans fatty acid content in foods contributed to lowered concentrations of trans fat in Canadian women's breast milk samples collected in 2009-2011.

Background: Recent efforts in Canada to reduce industrial trans fatty acids (TFAs) in foods include mandated inclusion of TFA content on food labels and recommendations by Health Canada that encourage the food industry to voluntarily limit TFA content in all vegetable oils and soft margarines and in all other prepackaged foods to <2% and <5% of total fat, respectively.

Objective: To assess the impact of these efforts, we measured the concentration of TFAs in human breast milk samples.

Design: The TFA content in 639 breast milk samples collected in 2009, 2010, and 2011 from breastfeeding mothers in 10 major cities across Canada was analyzed by gas chromatography.

Results: The mean (±SD) TFA contents were 2.7 ± 0.9% (n = 153, range: 1.4-7.2%), 2.2 ± 0.7% (n = 309, range: 1.0-6.8%), and 1.9 ± 0.5% (n = 177, range: 0.9-3.4%) of total milk fat for samples collected in 2009, 2010, and 2011, respectively. These values are considerably lower than the value of 7.2 ± 3.0% (range: 0.1-17.2%) found previously for Canadian human milk in 1992. On the basis of a linear correlation between the percentage of TFAs in the diet and human milk fat established by Craig-Schmidt et al, and assuming that 30% of energy of a lactating mother's diet is derived from fat, we estimated from the TFA human milk fat data that TFA intake of Canadian breastfeeding mothers was 0.9%, 0.5%, and 0.3% of total energy in 2009, 2010, and 2011, respectively. These estimated values are lower than the WHO's maximum recommended intake of 1% of total energy for a healthy diet.

Conclusions: The results suggest that the trans fat labeling regulations introduced in 2003 and recommendations by Health Canada in 2007 instructing the food manufacturers and restaurants to limit TFAs in foods have resulted in significant reductions in TFAs in the diets of Canadian breastfeeding mothers and their breast milk.