Disease Rates of Vegetarians and Vegans
In summary, not enough is yet known about vegan mortality to draw any conclusions other than that vegans do not have unusually high rates of mortality and they probably do better than the average person due either to diet or a healthier lifestyle.
Below is a summary of the research done on mortality and disease rates of vegetarians. It does not include cancer rates which can be found on the Cancer, Vegetarianism, and Diet page.
For an explanation of the different types of studies and their pros and cons, please see the article Basics of Nutrition Research.
The following studies have compared disease rates between people with different diets but similar lifestyles: