Erik Marcus comments:
This is yet another reason to tread carefully when discussing the health benefits of veganism—which is a point I’ve been making ever since Meat Market came out.
We could go even further, though, since the vegan diet isn't just fruits and veggies. Even if fruits and veggies did have magical properties, this wouldn't be an argument against eating chickens and fishes. (Similarly, the connection between red or cured meats and some cancers isn't a pro-vegan argument; it is taken by the general public as another reason to eat more chickens and fishes.)
Instead of looking at studies comparing disease rates with various intake of foods, Jack has done a review of cancer and actual vegetarians:
Table 1 below shows that no study has found a difference in mortality between vegetarians and meat eaters for all cancers combined. ... In Table 2 below, EPIC-Oxford found that people who ate fish but no other meat had the least amount of cancer.
All this reinforces Erik's point about the pitfalls of promoting "the health argument."
Unfortunately, this can be a very hard lesson to learn. We naturally suffer from confirmation bias; we note studies that, at first glance, seem to be pro-veggie, but ignore actual studies of vegans and vegetarians. We focus on people who stopped eating animals for their health, but we don't note all the people who stopped eating big animals and are now consuming many, many more chickens and fishes.
this picture. It is likely we'll catch more new vegetarians with Almost Philly Cheesesteak & Midway French Fries than with broccoli!