From Seed to Seed:
Plant Science for K-8 Educators

Food Categories: The Big Three

We'll begin by looking at three categories that are familiar to us as important components of the foods we eat: carbohydrates, oils/fats, and proteins. So many diet plans stress one or another of these categories-Eat more carbohydrates! Eat less fat! Eat more protein! Eat fewer carbohydrates! When exploring this topic with your students, take advantage of the opportunity to discuss how diet can impact human health, specifically, the role that plants can play in a healthy diet.

What do these three groups have in common?

First, carbohydrates, oils/fats, and proteins are all macromolecules. A macromolecule, as the name implies, is simply a large molecule formed by combining many smaller molecules. In addition, they are all organic molecules. Technically speaking, an organic molecule is one that contains the element carbon. It's easiest to think of organic compounds as substances associated with living organisms.

Where do they fit into human nutrition? Water, minerals, vitamins, carbohydrates, lipids (oils and fats), and proteins are vital to humans. The last three are called the organic macronutrients because they are organic (they contain carbon) and they are the major constituents of the foods we eat.

Now let's have a look at each of these macronutrients individually.