Where do you see that, proof?
Let's make sure we are on the same page here. I'm NOT saying that you cannot survive as a vegetarian, you can. You have vitamin supplements that can substitute for Vitamin b12 which is found in all animals and only a few plants. However, from what you are posting, you are saying that it's absolutely unnecessary to eat meat which I find to be completely false. Without all the necessary proteins and vitamins you need in your daily diet, missing one can result in and is possible to obtain sight problems, skin problems, blood diseases, mouth diseases, fatigue, Memory loss, rickets, osteomalacia, Osteoporosis, bone problems, and intestinal disorders. You don't get these all the time, but without meat and almost all of the necessary properties that come with it can keep you in a good bill of health. Though I think possibly that the main cause of the argument is that we are arguing based off of two presuppositions (world views). You feel guilty when you eat a burger and find the prospect of killing to obtain food wrong, where I do not.
TL;DR you can be a vegan/vegetarian and live, but you cannot say that eating meat is entirely unnecessary because it is.