The answer is technical. Let me use an analogy to assist us:
A house is a combination of foundations, floors, walls, windows, doors and a roof. Inside the house can be beds, a fridge, a TV, a mirror and many other things.
Similarly, food is a combination of fat, proteins and carbohydrates. These are called the macro-nutrients. Inside the food can be Calcium, Iron, Vitamin D, and many other micro-nutrients.
As a bath is not very useful without a house, micro-nutrients cannot be eaten as food. They form important minuscule parts of the food we eat.
Food processors’ marketing departments craft convincing messages about micro-nutrients being the be-all and end-all for childhood growth. This is simply misrepresenting facts. They do this because micro-nutrients can cheaply and more importantly, profitably be added to recipes.
As with foundations and walls of houses, the pillars of food are the quality and bioavailability of its fats and proteins. Food scientists agree that animal-sourced fats and proteins are important to child growth and building of their immune systems.
Carbohydrates are one of the macro-nutrients that provide some energy and fiber to the body and assists in carrying some of the micro-nutrients.