The Economist magazine has a special report on feeding the world in their latest issue. One of the major challenges is ensuring that people get the right nutrients, even if they are getting enough calories. Abhijit Banerjee quotes George Orwell writing in 1937 on the British working class to highlight the importance of cultural norms as an obstacle to good nutrition: 

The basis of their diet is white bread and margarine, corned beef, sugared tea, and potatoes—an appalling diet. Would it not be better if they spent more money on wholesome things like oranges and wholemeal bread, or if they … ate their carrots raw? Yes it would, but the point is, no ordinary human being is ever going to do such a thing. The ordinary human being would sooner starve than live on brown bread and raw carrots. And the peculiar evil is this, that the less money you have, the less inclined you feel to spend it on wholesome food. A millionaire may enjoy breakfasting off orange juice and Ryvita biscuits; an unemployed man doesn’t.