Nutrition, Labeling, and PackagingDo you know which foods you should eat to help you stay healthy? Do you know how to read a food label to help you choose the healthiest food products in the supermarket? Nutrition is the process by which the foods we eat provide the nutrients we need to grow and stay healthy. Nutrients are naturally occurring chemical substances found in food. There are six categories of nutrients: proteins, lipids, carbohydrates, vitamins, minerals and water.

Proteins contain amino acids, sometimes referred to as the building blocks of protein. Dietary protein is supplied from plant and animal sources. Proteins are needed to build and repair body tissue and for the metabolic functions of our bodies.

Lipids include fats and oils from plants and animals. Cholesterol is a fat found only in animal products. Lipids are of special interest because they are linked to the development of heart disease, the leading cause of death among Americans.

The carbohydrates in our diet come from plant foods. Simple carbohydrates include the different forms of sugar, while complex carbohydrates include starches and dietary fiber.

Vitamins are chemical compounds in our food that are needed in very small amounts (in milligrams and micrograms) to regulate the chemical reactions in our bodies.

Minerals, also needed only in small amounts, have many different functions. Some minerals assist in the bodyís chemical reactions and others help form body structures.

Fifty to sixty percent of our body weight consists of water. It is the substance in which the metabolic reactions occur. We need about two quarts (2 liters) of water every day.

Protein, fats and carbohydrates in food provide the energy, or kilocalories (kcals), our bodies need to function. Each gram of protein and carbohydrate has 4 kilocalories; each gram of fat has 9. You might have noticed that we use the metric system - grams, milligrams and micrograms - to measure the amounts of nutrients in foods.