The short-term impact of dietary fat and sugar intake on breast milk composition: A clinical trial protocol

Background: Breast milk is uniquely designed for the infant and contains the key nutrients and bioactive factors required to support optimal infant health and development. While previous studies have reported that maternal obesity can influence milk composition, whether this relationship is driven by maternal or dietary factors remains unclear. Aim: The aim of this study is to assess the impact of test meals varying in fat and sugar content on post-prandial concentrations of macronutrients and metabolic hormones in the breast milk. Methods: This open label crossover study will include 25 lactating women. On the three days of the intervention, women will be randomized to receive a breakfast meal with a fat and sugar content consistent with the Australian Guide to Healthy Eating (9 g fat, 25 g of sugar) or a breakfast meal containing higher levels of fat (28 g fat, 18 g of sugar) or sugar (5 g fat, 56 g of sugar). All breakfast meals will be similar in composition (cereal, milk, yogurt, toast and spread) and matched for total energy content. This study will measure breast milk concentrations of metabolic hormones (leptin, insulin, adiponectin, ghrelin and glucagon-like peptide-1) and macronutrients in the following 12 hours. Results and Conclusion: The results of this study will provide novel direct evidence of the impact of variations in dietary fat and sugar content to alter the macronutrient and/or metabolic hormone concentrations in breast milk. Data on the effect of maternal diet on milk composition is critical given the established importance of nutritional exposures in early infancy for an individual’s life-long health outcomes.