There are three types of caloric
foods. They are proteins made of amino acids, carbohydrates made of sugars,
and fats and oils made of fatty acids.
Proteins are a special
class of macronutrients, because they also provide the building
blocks for tissue proteins, hormones and enzymes. The building blocks
are called amino acids and the dietary source of amino acids is
protein. Thus, dietary protein always provides amino acids, including
all essential amino acids. No matter what food source, if it contains
proteins, it contains all 20 amino acids. There are some differences
in the proportions of amino acids from individual food groups known
as the biological value of proteins.
Carbohydrates are like
proteins versatile energy dense foods. They are rapidly metabolized
and unlike fats cannot be stored in large quantities in the body.
Unfortunately, carbs cannot replace fats, because they are also
important for tissue growth and regulation of metabolism. Besides
carbohydrates are important components of the immune system contributing
to the recognition of invading particles such as viruses and bacteria.
An important functional aspect of carbohydrates is the determinants
of blood groups A, B, and O.
Fats & Oils
Fats and oils have often
a bad reputation but are as important as proteins and carbohydrates.
Fats and oils are part of a large group of nutrients called lipids,
many of which are found only in very small quantities, such as cholesterol,
phospholipids, and fat soluble vitamins. In addition, some polyunsaturated
fatty acids (omega fatty acids) play important roles in tissue growth,
immune defense, and wound healing.