I was bewildered by all the Internet chatter about the picture of Victoria Beckham kissing her children on the mouth. The horror and the outrage!

That same day I was discussing feeding babies spoon foods, and a mother wondered what they did before blenders. Good question, because these two things are connected.

Transitional feeding seems to be necessary for humans from around six months of age. It is a time when breastfeeding doesn’t yield enough iron or protein to maintain optimal growth in babies.

In many animals the mother prepares soft foods by chewing it herself and then transferring it into the baby’s mouth. It’s called pre-mastication.

This mouth-to-mouth feeding occurs in many animals right up to primates. It was prevalent in the human in the past, and still is in some of the developing world (and occasionally Hollywood1).

It is also called ‘kiss-feeding’ and has been suggested that it is the origin of kissing people we love, though with the vast number of sensitive nerve ending on the lips I suspect we would have discovered it anyway…

But pre-mastication of food has advantages to little humans not just because of the access to a broader range of foods, but it also seems to boost their immunity. By contact with the different germs and proteins from their mother’s mouth, their immune system develops a wider variety of useful antibodies. This effect, and a decrease in the incidence of food allergies, has also been described in those babies whose mothers clean their dummies, not by formally sterilizing them, but putting them in their own mouth2.

Of course it would be important that the mother does not carry any infectious disease that can be transmitted via saliva (HIV, active oral herpes in particular, but any upper respiratory tract infection would also qualify).

But if you are healthy, you can kiss your kids on their mouths for as long as they let you!

  1. http://www.huffingtonpost.com/news/alicia-silverstone-pre-mastication/
  2. Hesselmar et al (2013), ‘Pacifier cleaning practices and risk of allergy development’, Pediatrics. Published online May 6 2013.