NUTRIENTS AND THEIR FUNCTIONS
To maintain health and function properly, the body must be provided with nutrients. Nutrients are chemical substances that are necessary for life.They are divided into six classes:
· Carbohydrates (CHO)
· Fats (lipids)
The body can make small amounts of some nutrients, but most must be obtained from food in order to meet the body’s needs. Those available only in food are called essential nutrients. There are about 40 of them, and they are found in all six nutrient classes.
The six nutrient classes are chemically divided into two categories: or-ganic and inorganic (Table 1-1). Organic nutrients contain hydrogen, oxygen, and carbon. (Carbon is an element found in all living things.) Before the body can use organic nutrients, it must break them down into their smallest compo-nents. Inorganic nutrients are already in their simplest forms when the body ingests them, except for water.
Each nutrient participates in at least one of the following functions:
• Providing the body with energy
• Building and repairing body tissue
• Regulating body processes
Carbohydrates (CHO), proteins, and fats (lipids) furnish energy.Proteins are also used to build and repair body tissues with the help of vitamins and minerals. Vitamins, minerals, and water help regulate the various body processes such as circulation, respiration, digestion, and elimination.
Each nutrient is important, but none works alone. For example, carbohy-drates, proteins, and fats are necessary for energy, but to provide it, they need the help of vitamins, minerals, and water. Proteins are essential for building and repairing body tissue, but without vitamins, minerals, and water, they are ineffective. Foods that contain substantial amounts of nutrients are described as nutritious or nourishing.