The antibacterial properties of breast milk

lab_technicianMany years ago, breast milk was thought to be sterile. While this is far from being the case (it actually contains all manner of germs1), the role it plays in helping keep babies free from harmful disease means it does display some pretty impressive bug-busting capacities.

The immunological components of breast milk help to protect both a mother’s breast and her baby from infection during feeding, as well as aiding the development of the baby’s immune system2. They also have another useful consequence, however: protecting breast milk from disease for some time after it has been expressed, enabling it to be stored. Several studies have examined whether it is safe to keep expressed milk for short periods, and there is general agreement that it can be stored for 8 hours at room temperature (25 degrees C), for three days in the fridge (4 degrees C) and for up to a year in the freezer (-20 degrees C) without any increase in the levels of pathogens (harmful bacteria) it contains3.

Not only does breast milk inhibit the growth of pathogens, however – it actively reduces them. This was convincingly demonstrated in a piece of research examining what happened to milk during short term storage4. Milk was collected from 9 mothers and divided into three samples: the first was analyzed the same day; the second was refrigerated (at 4 to 6 degrees C) for 48 hours; and the third was refrigerated for 72 hours. Each sample was then contaminated with an E.coli solution (the kind of nasty bacteria that dwells in toilets) and left for two hours. When the samples were tested, levels of E.coli had reduced by 80% in both the milk that was fresh and the milk that was 48 hours old. Levels had also diminished in the 3 day-old milk, but only by around 10%, indicating that the antibacterial properties, whilst still present, had started to degrade by this point.

If your baby needs to feed from a bottle or cup, a considerable body of research indicates that it’s safe to give him breast milk that has been stored in the fridge for up to three days, or in the freezer for several months. There is also evidence that if the milk you express does come into contact with germs (keeping pumping equipment sterile in your bag at work isn’t always easy), then the bactericidal components of breast milk should be able to take care of them, providing the milk is under two days old. There may still be potential issues associated with feeding stored, rather than fresh breast milk to your baby: various chemical changes occur in milk once it has left the body, and it’s possible some of these may affect its nutritional value3,5,6. Nevertheless, expressed breast milk remains a healthy alternative to formula, and as a result of its antibacterial qualities, you can rest assured that if your baby can’t feed from you directly, he still has a safe source of food and drink.

  1. Mastitis: causes and management. World Health Organization; 2000.
  2. Adv Food Nutr Res. 2008;54:45-80.
  3. Acta Paediatr Suppl. 1999 Aug;88(430):14-8.
  4. J Pediatr Gastroenterol Nutr. 2007 Aug;45(2):275-7.
  5. Acta Paediatr. 2001 Jul;90(7):813-5.
  6. Biofactors. 2004;20(3):129-37.
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Battle with the bottle: persistence pays off

bottle_2When C was about 10 weeks old, she started refusing to feed from a bottle. Initial reluctance rapidly turned into violent resistance, and if I actually managed to get the teat near her mouth, it was met only by screams.

My despair at the situation was tempered only by the fact that it turned out not to be particularly unusual. Two mothers I knew had had the same experience – trouble free bottle feeding morphing into complete refusal – and several others (including, ahem, my own mother) had never managed to get their babies to feed from a bottle.

On the web, several discussion forums were devoted to the topic, and here I found a glimmer of hope: many parents who had experienced similar problems had eventually been able to get their babies to accept bottles. Reading the advice was nevertheless confusing. There were a multitude of conditions that apparently dictated whether infants would feed from a bottle: mothers needed to be around to provide comfort/mothers needed to be completely out of the house; babies shouldn’t be really hungry (they might get too upset)/babies should be really hungry (they won’t let themselves starve); silicon teats were better than rubber/rubber teats were better than silicon…

The only thing that all the success stories had in common was that the parents persisted in offering their children bottles. This in itself is not a great revelation – if a bottle isn’t offered, then it cannot be accepted – but it was reassuring to know that just because a baby resolutely refuses a bottle at one point, it doesn’t necessarily mean she always will.

Keeping this in mind, we started to offer C a bottle everyday, containing just an ounce of expressed milk to start with. I abandoned my frustration, and decided not to worry too much whether she took it or left it. Perhaps because I was no longer anxious, C stopped crying when the bottle was near her. Sometimes she drank a little bit of milk, sometimes she just chewed on the teat, sometimes she spat it out. Eventually, she became so comfortable feeding this way that she’d grab the bottle with both hands and help push it into her mouth! Whether it was decoupling the stress from the situation, the increasing familiarity of the bottle, or a sudden turnaround that would have happened regardless of what we had done is impossible to know, but for now at least, bottle refusal is thankfully in the distant past.