Nutrients and Bioactive Components of Human Milk After One Year of Lactation: Implication for Human Milk Banks

OBJECTIVE

Specifying the nutrient content and bioactive compounds in milk from long-term lactation for the purpose of finding additional sources of donors' milk for human milk banks.

METHOD

Human milk samples were collected from 43 mothers of term infants (term infant human milk, TIHM) (3-6 weeks of lactation) and 50 mothers who have breastfed for over a year (long-nursing human milk, LNHM). The milk collection time was 24 hours. The analyses of fat, protein, carbohydrate and energy content were performed with human milk analyzer MIRIS (Miris HMA™ ); lactoferrin and vitamin C content using high performance liquid chromatography in reversed phase (RP-HPLC); total antioxidant activity (TAC) and lysozyme by enzyme-linked immunosorbent assay (ELISA); and the activity of glutathione peroxidase (GPx) and catalase (CAT) via spectrophotometric methods. Sociodemographic characteristics of both groups of mothers have been compiled.

RESULTS

Higher fat content and energy value was found in LNHM than in TIHM. Protein content in LNHM and TIHM did not differ. Carbohydrate content was lower in LNHM than in TIHM. TAC, CAT and GPx activity were higher in LNHM compared to TIHM. No significant differences in the content of lysozyme, lactoferrin and vitamin C between the studied groups were found.

CONCLUSIONS

The findings suggest that after 12 months of lactation, human milk still has significant nutritional value, does not lose bioactive components and can be considered for use in human milk banks.

Neurotrophic Factors in Human Milk in Early Lactation and the Effect of Holder and Microwave Pasteurization on Their Concentrations

OBJECTIVES

The objective of this study was to determine the level of brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF) in human milk in the first 2 weeks of breast-feeding and compare the effects of Holder pasteurization (HoP, 62.5 °C, 30 minutes) and microwave pasteurization (MP) at constant temperature (62.5 °C) on the concentraion of both neurotrophic factors (NFs).

METHODS

Concentration of NFs in human milk was determined using a commercially available ELISA assay.

RESULTS

The average concentration of BDNF and GDNF in milk was 11 ± 6 ng/mL and 336 ± 238 pg/mL, respectively. There was a positive correlation between the concentrations of BDNF and GDNF in human milk and day of lactation (r = 0.441, P < 0.05 and r = 0.482, P < 0.05, respectively). In addition, there was a significant correlation between the levels of BDNF and GDNF (r = 0.366, P < 0.05). HoP and MP for 10 minutes affected both NF levels similarly, causing degradation of BDNF by about 24% and 17%, and GDNF by 47% and 45%, respectively. Use of MP for 5 minutes resulted in preservation of nearly 91% BDNF and 79% GDNF in human milk.

CONCLUSIONS

In the pasteurization processes carried out, results showed that GDNF is more susceptible to degradation under the influence of high temperature. To the authors' best knowledge, this is the first study evaluating the effects of HoP and MP at constant temperature on the concentration of NFs in human milk. It was found that the MP for 5 minutes is the optimal method.