The research generally shows that breastfeeding does not protect against allergy.
As I understand it, the evidence is contradictory, and some research has been funded by formula manufacturers and the baby food industry. Given the controversy, the NHS have withdrawn 'protection from allergy' from their list of the many benefits of breastfeeding (see here ) but they still say that breastfed babies have less chance of developing eczema.
An Australian study appeared to show that ebf babies were at slightly greater risk of developing allergies - there is an Australian newspaper report about it here - but many experts disagreed with the conclusions drawn from the evidence.
It would be a bit premature to stop breastfeeding just because of one or two slightly suspect studies into possible links with allergy. The general benefits of breastfeeding are widely documented.
I had no breastfeeding support at all from the medical profession when I first noticed my baby was showing signs of allergy, despite the NICE guidelines saying that I should have been given advice about exclusion diets. My own exclusion diet was pretty extreme for a while, and I did it without the knowledge or support of any health professionals.
Until dieticians and allergy specialists start supporting breastfeeding mums a little better, exclusion diets will continue to be seen as weird or extreme. It is possible to follow an exclusion diet and be healthy, but mums who choose to follow exclusion diets without medical support are at risk of being very poorly nourished themselves (even though they will still make nutirionally adequate milk for their babies).
The phrase "you have to think of your own health" still makes me grind my teeth, even after four years! I would gladly sacrifice my own health to keep my children safe! However, I was careful to eat a balanced diet despite the restrictions, and my long-term health is fine (I still eat the same restricted diet as my allergic DS).
Sorry this is such a long and rambly post - it winds me up when people say that breastfeeding is bad for allergic babies!!