Introduction <p>This study aimed to elucidate the relationship between maternal nutrition and the quantity and composition of breast milk.</p> Methods <p>All mothers were administered sequentially, with each lasting one week, a healthy nutrition diet, a carbohydrate-rich diet, and a protein-rich diet.</p> Results <p>Compared to the healthy nutrition diet, a statistically significant increase was observed in the levels of glutamic acid, serine, glycine, histidine, tyrosine, valine, isoleucine, leucine, and lysine in milk following the carbohydrate-rich diet (<i>p</i> &lt; 0.05). In contrast to the healthy nutrition diet, the lactose content of milk decreased after the carbohydrate-rich diet and increased after the protein-rich diet (<i>p</i> &lt; 0.05). Following both carbohydrate-rich and protein-rich diets, a reduction in riboflavin content in milk was observed compared to the healthy nutrition diet (<i>p</i> &lt; 0.05). After the protein-rich diet, an increase in milk quantity was observed compared with the carbohydrate-rich diet (G1, <i>p</i> = 0.006; G2, <i>p</i> = 0.001). A negative correlation was found between the mothers’ body weight in the third week and the amount of amino acids in their milk (<i>r</i> = -0.270, <i>p</i> = 0.037).</p> Conclusions <p>The results of this study indicated that the nutrient composition and quantity of human milk are influenced by maternal nutrition.</p>