the best sus' on longevity is roy walford's
calorie restriction with adequate nutrition,
his CRAN or high/low diet extraoplated from very many
animal experiments dated from the 1930s.
there are on-going primate studies in this field as
well. nothing would be correlated with blood groups.
but i think a good place to look is with the
japanese in okinawa.this population has the most
centarians per 1000 in japan.they eat a low cal
diet with plenty of fish/tofu/veggies;make a
search on them.japan of course in well in to
blood groups......."hello!and what blood group are you?"
so i think you could find if a typical diet
correlates more strongly with centarian survival
and specific blood grouping or not.
but of course that does not spread the net very
widely.still it is a start.i wonder if you come up with anything!