I dont think there is an official classification as Pesco Vegan but it comes closest to describing how I eat these days. I avoid dairy and meat but eat fish such as wild salmon, mackerel, sardines and my favourite anchovies on sliced tomato. I try not be too neurotic about food. For example if you invited me to your house and chicken was on the only choice I would eat it, happy that this means I am eating chicken only once every blue moon.
Getting into a debate on Vegan/Pesco etc Vs meat eaters with regard to health and longevity can be pretty hairy if you are in the wrong company. I must be one of few people who have taken a battering on Nutritionfacts.org ( a veggie based community) for my suggestion that cholesterol levels are not the main driver of heart disease whilst getting similar treatment on Dr Kendricks blog which is populated by saturated fat and meat advocates when suggesting that Pesco’s are the top dogs in the health game.
The main problem with the latter debate is the existence of confounders. For example randomly looking at meat eaters against vegetarians may well include more smokers in the former and the fact that the latter have made some conscious diet changing move could mean they are generally more health living types.
The study I like quoting however is the Adventist Health Study 1 and 2
In this study Pescos clearly came out top with the lowest risk ratio for overall mortality. I like this study because it has a relatively tight cohort in that all subjects are from the same religious group and hence have closer matched support networks than taking subjects from the general population.