• Human milk;
  • diet;
  • stage of lactation;
  • trans fatty acids

Aim: To determine the content of trans fatty acids in human milk in relation to breastfeeding mothers’diet. Methods: Samples of milk were collected from 100 breastfeeding mothers and 7-d dietary records and anthropometry from 69 mothers were obtained. Results: The following total trans fatty acids contents (median (lower-upper quartile); % wt/wt) in milk samples were determined: 1) data for Spring: colostrum—1.37 (1.00–2.00), mature milk at 5–6 wk of lactation—2.59 (1.49–3.34) and at 9–10 wk of lactation—2.36 (1.55–3.92); 2) data for Autumn: colostrum—1.80 (1.42–2.48), mature milk at 5–6 wk of lactation—2.41 (1.79–4.31) and at 9–10wk of lactation—2.77 (1.53–4.18). The major sources of trans fatty acids in mothers’diets were bakery products, confectionery and snacks. Mothers who had high level of trans isomers in their milk consumed significantly higher amounts of these products.

Conclusions: Bakery products, confectionery and snacks are a major source of trans fatty acids in maternal diet in Poland. The levels of trans fatty acids in human milk may reflect the current diet of the mother as well as the diet consumed early in pregnancy.