not intuitive. and I haven't seen ground for that line of
reasoning.
For your monks and nun theory.
1) Note that they typically eat steamed and bland food =>
less carcinogens cos won't chao tar.
2) They also may not go out into the city or traffic much and
thus are exposed to less of the toxic air.
3) I believe they probably eat less processed foods then the
rest of the population do too.
I believe there are 101 reasons.
of course there are 101 reasons and environmental factors
involved.
but does the basic premise change ? that eating more vegs and
less meat is good for you ?
regardless of the reasoning, whether it's the pH of the blood,
or the karmic debt of killing and eating animals, or anti-oxidants
in vegs, or urea in meat or whatever, no ? 
but wow ... the irony here ..... suddenly, I'm a healthy living
proponent .... 
