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Carbohydrates
Digestible carbohydrates are simple sugars or complex
starches in structure.
Protein
Proteins are sometimes called the "staff of life"
and are essential for growth and development. These
large molecules are made up of building blocks called
amino acids. We require about 20 amino acids to build,
repair, and maintain our many different body tissues.
Fats
Fats are the third primary source of calories. When
you compare the 9 calories/gram provided by fats with
the 4 calories/gram for both carbohydrates and protein,
it's easy to see why people who eat a high-fat diet
typically get a lot of calories. Health authorities
have emphasized the need to reduce dietary fat intake,
although the body does need some fat. During infancy
through two years of age, fat is necessary for brain
development. After the age of two, the body only needs
small amounts of fat. The typical American diet is much
higher in fat than what the body requires. Consuming
excessive amounts of fat is a major causative factor
in coronary heart disease, high blood pressure (hypertension),
obesity, certain types of cancers, and has been linked
to a number of other disorders as well.
Vitamins &
Minerals
Vitamins are essential organic nutrients that don't
provide calories. Most vitamins were discovered when
scientists identified substances in foods that cured
specific deficiency diseases.
Vitamins act as agents to control cell metabolism and
are components of body tissues. They are classified
as being soluble in fat or in water. The fat-soluble
vitamins are A, D, E, and K. The water-soluble vitamins
are vitamin C and the eight B-complex vitamins-thiamin,
riboflavin, niacin, Vitamin B6, pantothenic acid, biotin,
folate, and Vitamin B12.
Water
Water is the single largest component of the human body,
making up about 60% of your total body weight. You get
water by drinking it and from various foods. Your body
loses water in urine, bowel movements, perspiration,
and exhaled air.
"Non-Nutrients"
Many substances in food affect your health even though
they aren't classified as nutrients.
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