Nutrition can be defined as the science of the action of food, beverages, and their components in biological systems. A nutrient is a compound that provides a needed function in the body. Nutrients can be further classified based on the amount needed in the body. Macronutrients are the nutrients the body needs in larger amounts. Micronutrients are also important nutrients, but ones the body needs in smaller amounts.
- Carbohydrates: The word carbohydrate literally means "hydrated carbon," or carbon with water. Thus, it is no surprise that carbohydrates are made up of carbon, hydrogen, and oxygen. Sucrose (table sugar) is an example of a commonly consumed carbohydrate. Some dietary examples of carbohydrates are whole-wheat bread, oatmeal, rice, sugary snacks/drinks, and pasta.
- Proteins: Like carbohydrates, proteins are comprised of carbon, hydrogen, and oxygen, but they also contain nitrogen. Several dietary sources of proteins include nuts, beans/legumes, skim milk, egg whites, and meat.
- Lipids: Lipids consist of fatty acids, triglycerides, phospholipids, and sterols (cholesterol). Lipids are also composed of carbon, hydrogen, and oxygen. Some dietary sources of lipids include, oils, butter, and egg yolks.
- Water: Water is made up of hydrogen and oxygen and is the only macronutrient that provides no energy.
- Vitamins: These compounds are essential for normal physiologic processes in the body.
- Minerals: Minerals are the elements (think periodic table) that are essential for normal physiologic processes in the body.