Many mothers wonder why the non-profit HMBANA human milk banks pasteurize their milk. Laraine Lockhart Borman, IBCLC, with the Mothers’ Milk Bank in Denver, explains…
The HMBANA Advisory Council, a panel of experts in areas of infectious disease, microbiology, neonatology, law, and other areas, determined that because human milk has the potential to be an agent of infectious disease, pasteurization would be required of all member banks due to the extremely fragile health of the babies receiving this milk. The number one priority is the health and safety of the tiny preterm infants served.
With any type of storage or treatment of human milk, there is some loss of its original components. Mother’s milk that has been frozen and stored experiences a loss of vitamin A from exposure to light and vitamin C from exposure to freezing temperatures. Pasteurization is a very gentle, controlled heating process using special equipment that kills viruses and bacteria while still maintaining 95% of everything that was originally in the milk. While a few of the immune properties are lost, there are many more that survive the pasteurization process. In addition, some beneficial enzymes are actually activated by the pasteurization process. *
Bottom line is that mom’s own milk is best. When this is not available, pasteurized human milk, obtained from a certified milk bank, can be a lifesaving safe and healthy alternative that everyone can feel good about.
From “Donor Human Milk for Preterm Infants” (Wight 2001):
The benefits and concerns regarding the use of human milk for preterm infants has been recently reviewed, with more factors, actions, and interactions being discovered frequently… Protective effects of human milk on infection rates have been observed with the use of both fresh and pasteurized milk…
[note: see Heiman & Schanler 2006 for a recent review]
Pasteurization (56 or 62.5°C for 30 minutes) does affect some of the nutritional, immunologic and other components of human milk. Heat treatment at 56°C (133°F) or greater for 30 minutes reliably eliminates all functional white blood cells and bacteria, inactivates human immunodeficiency virus (HIV) and human T-lymphotropic virus, and decreases the titers of other viruses, but in one study did not eliminate cytomegalovirus (CMV). Holder pasteurization [62.5°C (144°F) for 30 minutes] reliably inactivates HIV and CMV, and will eliminate or significantly decrease the titers of most other viruses.
Immunologic factors are variously affected by heat treatment. With Holder pasteurization most of the secretory IgA, bifid growth factor, and lysozyme remain (0% to 30% destroyed), lipids are unaffected, but 57% of the lactoferrin, and 34% of the IgG are destroyed. The reader is referred to a more detailed recent review (Lawrence 1999).
In general, the nutritional components are altered somewhat, resulting in slightly slower growth when compared to infants fed unpasteurized raw human milk. Holder pasteurization does not appear to influence nitrogen absorption or retention in LBW infants. Most enzymes, growth factors, vitamins, and minerals are unchanged or minimally decreased. Heat treatment of donor milk appears to foster more rapid growth of intestinal epithelial cells by inactivating heat-labile inhibitory cytokines, allowing heat-stable epidermal growth factor to act. Freezing inactivates milk cells and most viruses, but does not appear to effect the nutritional or anti-infective quality of the milk. Microwaving clearly decreases the anti-infective properties of human milk; the higher the temperature, the greater the effect.
* Research: The effect of pasteurization on the anti-infective agents of human milk
Percent activity remaining after pasteurization at 62.5°C for 30 minutes (unless otherwise noted)
|Cells||78% macrophages||Gibbs 1977|
|No viable cells||Liebhaber 1977|
|IgA (total secretory)||39%
81% (56°C for 30 minutes)
77% (62.5°C for 5 minutes)
90% (56°C for 30 minutes)
64% (72°C for 15 seconds)
|150% (72°C for 15 seconds)||Goldblum 1984|
|Some loss (stable if 56°C for 30 min)||Welsh & May 1979|
58% (72°C for 15 seconds)
|IgM||Substantial loss||Liebhaber 1977|
96% (62.5°C for 5 min)
106% (56°C for 30 minutes)
|393% (72°C for 15 seconds)||Goldblum 1984|
|33%||Welsh & May 1979|
|123% (72°C for 15 seconds)||Goldblum 1984|
|Bile salt-stimulated lipase||Lost||Wardell 1984|
|Non immunoglobulin||Stable||Laegreid 1986|
|C1 – C9||Destroyed||Welsh & May 1979|
|L Bifidus growth factor||Stable|
|Antimicrobial activity||Stable (56°C for 30 minutes)||Bullen 1972|
|Antiprotozoal activity||Some stability||Gillin 1983|
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