Most Americans’ diets fall short of Federal recommendations, especially when it comes to whole grains, low-fat dairy products, and fruits and vegetables. Some nutrition researchers and food writers blame cost, saying fruits and vegetables and other healthy foods are more expensive than less healthy ones. And on a per calorie basis, that’s true. Calorie-sparse fruits and vegetables cost more than a donut, and skim milk costs more than whole. But is price per calorie the only way to think about a food’s cost?