I'm skeptical of this for a few reasons. Firstly, there's no food you can buy nowadays that hasn't been stripped of the majority of it's nutrients and replaced with poisons of some type or another.
So the people who are testing healthier by not eating meat, are still receiving plenty harmful substances by way of alternative food sources.
Also, the meat industry is a powerhouse of both political and economic influence. This is how they manage to get away with cutting down pretty much all of the amazon jungle to make room for cattle farms. I expect they would have the necessary pull to make sure that if anything, these tests were performed on the best possible meat products so as not to reveal just how awful the lower grade stuff is.
From personal experience, I can tell you that when I used to eat meat everyday, I was always tired. I haven't eaten any in over a year now, and I feel I have a lot more energy and am just healthier all round. I was probably eating the lower grade meat though so I don't how much that counts for..
Humans have clearly lost what every animal seems to still possess. They know instinctively what to eat and what not to eat. I think that by looking at our closest relatives in the animal kingdom who we share so much in common with, the chimpanzee, we can maybe learn from them what our diet ought to be. There diet consists of mostly nuts, seeds, fruit, vegetables and flowers, with a mere 2% meat/insects(allegedly).
Perhaps the natural human diet, the one that will keep us healthy for as long as possible, is not so dissimilar from this..
RE: The real reason eating meat/dairy is bad for you (It has nothing to do with what you are thinking)