tamum - that is OK. I missed out the end bit (sorry about that)which was .... "In several instances the protection seems to improve with the duration of breastfeeding."
That is a bit woolly so I did a bit more digging and found the following (just put in excerpts here)
Breastfeed a Toddler?Why on Earth?
Handout #21. Toddler nursing. January 2003
Written by Jack Newman, MD, FRCPC. © 2003
Breastmilk still contains immunologic factors that help protect the baby. In fact, some immune factors in breastmilk that protect the baby against infection are present in greater amounts in the second year of life than in the first. This is, of course as it should be, since children older than a year are generally exposed to more infection. Breastmilk still contains factors that help the immune system to mature, and which help the brain, gut, and other organs to develop and mature.
Immunological Protection
This article was originally written in 1999 by Kathryn Orlinsky.
Skeptics have said, "yes, human milk benefits infants, but older children cannot continue to receive immunity by breastfeeding, can they?" The answer to this question is a resounding yes. Children enjoy health benefits for as long as they breastfeed. Studies have compared weaned children with breastfeeding children at 30 months16 and at 36 months,20,23 and found them to be sicker.
There are at least two reasons why breastfeeding continues to benefit older children. First, human milk contains immune factors regardless of the duration of lactation. Both lysozyme and SIgA levels have been found in human milk for the entire period of lactation studied, including the second year.10,12,13 Many of these immune factors would be otherwise unavailable.13 Second, human milk is more easily tolerated by a sick child than weaning foods. Thus, breastfeeding ensures that sick children remain hydrated and do not lose excessive weight
References:
Gulick EE. 1986. Pediatr. Nurs. Jan-Feb;12(1):51-4. The effects of breast-feeding on toddler health.
Molbak K, Gottschau A, Aaby P, Hojlyng N, Ingholt L and AP da Silva. 1994. BMJ. May 28;308(6941):1403-6.
van den Bogaard C, van den Hoogen HJ, Huygen FJ and C van Weel. 1991. Fam. Med. Sep-Oct;23(7):510-5.
And as someone mentioned earlier the benefits to the mother ...
BBC Online 19.07.02
Thousands of women might be spared the agony of breast cancer if they extended the period for which they suckle their babies.
Research published on Friday suggests that for every year of her life spent breastfeeding, a woman's risk of the disease drops by 4.3%
This is on top of the 7% reduction she enjoys for every baby to which she gives birth.
This last point is important as women used to both have a lot more children and feed them for longer thus preventing cancers. So rather than having more kids which is impractical, we could feed the ones we do have for longer.