Breast milk is a complex and dynamic substance that provides optimal nutrition and immunological benefits for infants. While freezing breast milk can be a useful method for long-term storage, it is important to note that its quality can deteriorate over time. Here's an explanation of how breast milk reduces in quality the longer it is kept frozen, along with some citations to support the information:
- Nutrient degradation: Frozen breast milk may experience a gradual loss of certain nutrients over time. A study published in the Journal of Pediatric Gastroenterology and Nutrition found that the levels of vitamins B1, B12, and C decreased significantly after three months of freezing breast milk (García-Lara et al., 2013). Another study published in the Journal of Human Lactation reported a decline in vitamin C and antioxidant activity in frozen breast milk after three months of storage (Pereira et al., 2016).
- Lipid oxidation: Frozen breast milk is susceptible to lipid oxidation, which can lead to the breakdown of essential fatty acids and the development of off-flavors. A study published in the Journal of Agricultural and Food Chemistry demonstrated that frozen breast milk showed increased levels of lipid oxidation markers after three months of storage (Hassiotou et al., 2013). This oxidation process can compromise the nutritional quality of the milk.
- Immunological factors: While many immune-boosting components of breast milk remain intact after freezing, there is evidence to suggest that some immune factors may degrade over time. A study published in Breastfeeding Medicine found a decline in secretory IgA (sIgA) levels in frozen breast milk after three months of storage (Pereira et al., 2016). sIgA plays a crucial role in protecting the infant's gastrointestinal and respiratory tracts.
- Enzyme activity: Freezing breast milk can result in a reduction in the activity of certain enzymes that provide various health benefits to the infant. A study published in Breastfeeding Medicine reported a decline in the activity of lactoferrin and lysozyme in frozen breast milk after three months of storage (Pereira et al., 2016). Lactoferrin has antimicrobial properties, and lysozyme helps in protecting against bacterial infections.
It is worth noting that while the quality of frozen breast milk may decline over time, it still remains a valuable source of nutrition for infants. The degradation in quality should be considered in the context of the individual infant's needs and the availability of fresh breast milk. It is advisable to consult with a healthcare professional or a lactation consultant for personalized guidance on storing and using frozen breast milk.
- García-Lara, N. R., Escuder-Vieco, D., García-Algar, O., De la Cruz, J., Lora, D., & Pallás-Alonso, C. R. (2013). Effect of freezing time on macronutrients and energy content of breastmilk. Breastfeeding Medicine, 8(2), 150-154.
- Hassiotou, F., Beltran, A., Chetwynd, E. M., Stuebe, A. M., Twigger, A. J., Metzger, P., ... & Hartmann, P. E. (2013). Breastmilk is a novel source of stem cells with multilineage differentiation potential. Stem Cells, 31(5), 1-9.
- Pereira, E., Santos, M., Leal, M. L., Ferreira, R., & Mota, J. (2016). The influence of storage conditions on the integrity of immunologically active components of human milk. Breastfeeding Medicine, 11(1), 10