Lactose, oligosaccharide and monosaccharide content of milk from mothers delivering preterm newborns over the first month of lactation.

BACKGROUND: Monosaccharide, lactose and oligosaccharide content of milk from mothers delivering prematurely (PT milk) was studied to evaluate whether changes occur during lactation, as observed in milk from mothers delivering at term (T milk). METHODS: To study a homogeneous population, women having the most common phenotype (secretory both Lewis and A, B, or H phenotype) were selected. Milk samples from 26 mothers who delivered between the 27th and 35th week of gestation were collected at the 4th, 10th, and 30th post-partum days. Monosaccharides, lactose and oligosaccharides were measured by high-pressure liquid chromatography. RESULTS: Lactose concentration increased significantly (p < 0.05) from 52.81 +/- 8.2 g/L on day 4 to 69.24 +/- 9.36 g/L on day 30. During the same period of time oligosaccharide content decreased significantly (p < 0.05) from 25.61 +/- 5.19 g/L to 15.83 +/- 6.05 g/L. Monosaccharides did not show statistically significant variations. CONCLUSIONS: Our results indicate that PT milk contains in addition to lactose, a substantial amount of oligosaccharides and a lower percentage of monosaccharides. Compared to T milk, in the colostral phase PT milk presents significantly lower lactose concentration (p < 0.0001); on the contrary its oligosaccharide content is significantly higher (p < 0.0001). The physiological role of human milk carbohydrates in view of the peculiar needs of the preterm newborn is also discussed.