This updated systematic review examines the relationship between maternal diet and human milk composition, building on previous research by Bravi et al. (2015). The review includes 27 observational and 5 intervention studies, with a total of 7,138 participants. The findings indicate that maternal diet significantly influences the composition of human milk, particularly in terms of fatty acids. Maternal fish intake is positively associated with milk levels of alpha-linolenic acid (ALA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA). Dietary polyunsaturated fatty acids (PUFAs) are generally positively correlated with their concentrations in milk, while saturated fatty acid (SFA) intake is negatively associated with several fatty acids in milk. However, the association between maternal diet and milk carbohydrates, proteins, vitamins, and minerals is limited and varies in methods and results. The review highlights that evidence on the association between maternal diet and human milk fatty acids is increasing, but the methodology and results remain diverse. Further studies, particularly intervention studies, are needed to better understand the impact of maternal diet on the overall composition of human milk. The review also notes that dietary patterns, such as the Healthy Eating Index (HEI), are associated with milk fatty acid content. Additionally, specific food groups, such as fish, dairy, and plant-based foods, show varying associations with milk composition. The review concludes that while there is growing evidence of the influence of maternal diet on human milk composition, more research is needed to draw definitive conclusions about the importance of maternal diet for human milk composition.This updated systematic review examines the relationship between maternal diet and human milk composition, building on previous research by Bravi et al. (2015). The review includes 27 observational and 5 intervention studies, with a total of 7,138 participants. The findings indicate that maternal diet significantly influences the composition of human milk, particularly in terms of fatty acids. Maternal fish intake is positively associated with milk levels of alpha-linolenic acid (ALA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA). Dietary polyunsaturated fatty acids (PUFAs) are generally positively correlated with their concentrations in milk, while saturated fatty acid (SFA) intake is negatively associated with several fatty acids in milk. However, the association between maternal diet and milk carbohydrates, proteins, vitamins, and minerals is limited and varies in methods and results. The review highlights that evidence on the association between maternal diet and human milk fatty acids is increasing, but the methodology and results remain diverse. Further studies, particularly intervention studies, are needed to better understand the impact of maternal diet on the overall composition of human milk. The review also notes that dietary patterns, such as the Healthy Eating Index (HEI), are associated with milk fatty acid content. Additionally, specific food groups, such as fish, dairy, and plant-based foods, show varying associations with milk composition. The review concludes that while there is growing evidence of the influence of maternal diet on human milk composition, more research is needed to draw definitive conclusions about the importance of maternal diet for human milk composition.