“Eat food. Not too much. Mostly plants. – Michael Pollan” is the best 7-word nutritional advice one can give any human.
An excerpt:
That, more or less, is the short answer to the supposedly incredibly complicated and confusing question of what we humans should eat in order to be maximally healthy.
The whole essay: http://www.nytimes.com/2007/01/28/magazine/28nutritionism.t.html?pagewanted=all