Research on 18000 Swedish 16 year olds shows that 30-40 % of them have
some kind of allergy. They have been asked various questions about life
style, environment and so on. It does not give any answer to why
allergies have become 300-400% more common the last 40 years, but new
questions have arisen.
On interesting fact is that the ones who use butter on their bread have
less allergy than those who use margarine instead. And those who smear no
fat on their bread are the ones with most allergy problems!
(It is very usual to eat bread and "butter", usually with cheese or ham
on, in Sweden, several slices a day.)

- Hans