Nutritious food is not necessarily perfect food. Take tofu, for example. It is rich in high-quality protein, contains no cholesterol, and has a high calcium content. However, tofu has a small nutritional deficiency: it lacks the essential amino acid methionine, so it cannot be fully utilized by the body.
However, this deficiency in tofu can be compensated for by eating corn. Corn is rich in methionine but lacks lysine and serine, which are found in tofu. When eaten together, the nutritional absorption rate can be greatly improved. Using corn as a staple food, plus a tofu dish, makes for a very good main meal choice.