Epidemiological studies are insightful and highly suggestive, but they
cannot demonstrate cause and effect.  We don't know if the group that added
neither butter or margarine on the bread were also poorer, ate a diet high
in refined and processed foods, ate smaller amounts of quality protein, or
lived in highly pollution neighborhoods; all factors that could contribute
to "allergies".

Certainly the theory that those who added neither butter or margarine to
their bread ate more bread as a result seems plausible.  But how this
accounts for more "allergies" is less clear.

Rob
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> 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.)