Nutrition is the science that deals with food and how the body uses
it. All living things need food to live. The food supplies energy, which
people need to perform certain actions. Food also provides substances
that the body needs to build and repair its tissues and to regulate its
organs and organ systems.
Food provides certain chemical substances needed in order for a
person to maintain good health. These chemical substances are called
nutrients. Nutrients can perform three important functions. They provide
materials for building, repairing, or maintaining body tissues. They help
regulate body processes. They serve as fuel to provide energy. The
body needs energy to maintain all its functions. People who do not get
enough nutrients are sometimes lazy and are unwilling to work.
The foods we eat contain thousands of different chemicals. Our
body, however, only needs only a few dozen of these chemicals in order
to stay healthy. These are the nutrients that the body needs. Nutrients
are divided into six main groups. They are (1)water, (2)carbohydrates,
(3)fats, (4)proteins, (5)minerals, (6)vitamins. Water, carbohydrates, fats,
and proteins are called macronutrients. Since macro means large, the
body needs these four nutrients in large amounts. Minerals and vitamins
are called micronutrients (because micro means small). The body needs
only small amounts of these nutrients.
Water is the most important nutrient. Our bodies can survive
without other nutrients for several weeks, but we can only go without
water for about one week. Water is needed in great amounts because
the body consists largely of water. Between 50 and 75 percent of a
normal person's body weight is made up of water. The body needs water
to carry out all of its life processes. Watery solutions help dissolve other
nutrients and carry them to all of the tissues. The body also needs water
to carry away waste products and to cool itself. Adults should drink
about 2 1/2 quarts of water every day.
The carbohydrates, fats, and proteins are needed because they have
nutrients which provide energy.
Carbohydrates include all sugars and starches. They are the main
source of energy for living things. There are two types of carbohydrates,
simple and complex. Simple carbohydrates include sugars and have a
simple molecular structure. Complex carbohydrates include starches and
have a larger and more complicated molecular structure. The structure
consists of many simple carbohydrates linked together.
Fats are a highly concentrated source of energy. All fats are
composed of an alcohol called glycerol and substances called fatty acids.
A fatty acid consists of a long chain of carbon atoms. There are three
types of fatty acids. They are saturated, monounsaturated, and
polysaturated. This is a chart that describes the amount of fat per
serving. The bold words can be found on many food products in the
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