MATERNAL diet could influence the fatty acid composition of human milk, according to new research examining the relationship between nutrient intake and breast milk composition.
The cross-sectional study in the Netherlands assessed maternal dietary intake alongside the fatty acid composition of human milk collected postpartum, finding further evidence that maternal nutrition may contribute to the supply of fatty acids to breastfed infants.
Human milk provides approximately half of an infant’s energy requirements through fat, while its fatty acids have important roles in growth and development. Polyunsaturated fatty acids (PUFAs), including docosahexaenoic acid (DHA) and arachidonic acid (ARA), are particularly important for visual and neurological development and immune function.
While previous research has linked maternal fish and PUFA intake with breast milk fatty acids, evidence surrounding other dietary fats and micronutrients has remained inconsistent
For this study, researchers analysed 109 healthy women in the Netherlands who were exclusively breastfeeding at 6 -8 weeks postpartum. Participants had a mean age of 32.3 years and pre-pregnancy BMI of 22.1 kg/m².
Maternal diet was assessed using four non-consecutive 24-hour food records and a food frequency questionnaire, while two standardised morning milk samples were collected from each participant. The women consumed an average of 2,277 kcal and 97.0 g of fat daily.
Human milk contained an average of 4.03 g fat/100 mL, with saturated fatty acids (SFAs) accounting for 39.45% of total fatty acids, omega-6 fatty acids 14.23%, and omega-3 fatty acids 1.85%. DHA and eicosapentaenoic acid (EPA) accounted for 0.22% and 0.09%, respectively.
Researchers found that maternal omega-3 intake was strongly associated with milk composition. Each 1 gram per day increase in omega-3 PUFA intake was associated with a 0.63 percentage-point increase in milk omega-3 fatty acids. This remained similar after accounting for omega-3 supplementation.
Higher omega-3 intake was also associated with 2.29 percentage points more total milk PUFAs, as well as 3.43 percentage points fewer SFAs and 0.21 percentage points fewer trans fatty acids.
Similarly, higher omega-6 intake was associated with a 0.49 percentage-point increase in milk omega-6 fatty acids. Trans-fat intake was also positively associated with trans-fat proportions in milk.
Associations were found to extend beyond dietary fats. Higher intakes of vitamin B1, copper, vitamin E, and magnesium were associated with lower proportions of SFAs and trans fats, while magnesium, vitamin E, vitamin D, and vitamin B1 were associated with higher omega-3 levels.
Overall diet quality showed similar, although smaller, associations. Each one-point increase in healthy diet score was associated with increases of 0.01 percentage points in omega-3, 0.07 in omega-6, and 0.08 in total PUFAs.
The findings support previous evidence that maternal PUFA intake influences breast milk composition, while suggesting that micronutrients may also play a role in milk lipid metabolism.
However, the researchers emphasised that the study was observational, meaning causality cannot be established. Higher micronutrient intake may instead reflect a healthier overall dietary pattern, while the highly educated, healthy study population may limit generalisability.
Further studies are therefore needed to determine whether specific micronutrients directly influence human milk fatty acids. Nevertheless, the findings reinforce the potential importance of maternal diet in determining the fatty acids supplied to breastfed infants and how these will then go on to affect infant health.
Reference
Petersohn I et al. Maternal diet and fatty acids in human milk: results of the MELK study. European Journal of Nutrition. 2026;65:240.
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