Of course not.<p>Imagine a world where the government came out and said: for optimum health eat nothing but meat, fish, poultry and lots and lots of vegetables.<p>How in the world would you feed a population of 300+ million eating this way? You can't.<p>For this reason, we're encouraged to consume things that are easy to grow: wheat, rice, etc.<p>That was just a thought experiment - I am not trying to have the debate here of what the optimum diet is. I am just trying to provide a little perspective as to why under some circumstances the advice we're given may not always match up with research.