"some can eat a vegetarian diet and be just fine. others can't."
Good clean sources for meat are getting much harder to find... and now with Congress looking to re-define "organic" for meat among other things it may well make it near impossible to find clean sources. Clean being a relative term as everything is polluted these days including plants.
Organic silage fed to cattle in feed lots is not the same as pasture raised... very big difference in omega 3's and fat, not to mention the health of the animal.
I have not eaten beef or chicken in well over a month though and have been doing just fine with wild caught salmon and sardines at lunch.