Actually that is the one area where I do not agree with the movie. Even Pollan himself had agreed in an email with a low carber that meat was better for people. He just could not envision how we could feed enough people. Joel Salatin and him disagree on this point. The belief that we can't feed people meat in a sustainable way is wrong. No doubt an idea that Monsanto loves to promote.
Humans evolved to eat meat and healthy, natural fats. The fact that we can eat other things doesn't not make them the ideal food source. We get all nutrients we need with the exception of ONE from meat. The exception is vitamin C, but meat has 2 vitamin C precursors. The fewer grains, starches and sugars you eat, the less vitamin C you need.