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Again, inorganic mineral
nutrients are required to build body tissues. These nutrients also
participate in the action of enzyme systems, nerve reactions,
contraction of muscles and the clotting of blood. Among mineral
nutrients, there are two varieties: major elements and trace
elements. Calcium, phosphorus, magnesium, iron, iodine and potassium
form the major elements, while copper, cobalt, manganese, fluorine
and zinc are trace elements. A good intake of minerals in our daily
diet is strongly advised.
Vitamins enhance the
metabolism of proteins, carbohydrates and fats. They are responsible
for the breaking down and assimilation of foods. Certain vitamins
help form blood cells, hormones, nervous system chemicals and
genetic materials. Vitamins are classified into fat-soluble vitamins
(vitamin A, D, E, and K) and water-soluble vitamins (vitamin C and B
complex).
A great part of the
energy for the body comes from carbohydrates. Foods rich in
carbohydrates are usually the most abundant and cheapest.
Fats produce more than
twice as much energy as carbohydrates. Fats are efficiently stored
in the body for later use, when carbohydrates are in short supply.
Dietary fats are broken down into fatty acids that pass into the
blood. These fatty acids are categorized as saturated and
unsaturated. Saturated fats, derived mostly from animal sources,
have been found to raise the level of cholesterol in the
bloodstream, and certain unsaturated fats tend to lower it.
Of the food types that
we generally consume, breads and cereals are high in starches. Whole
cereals often supply significant amounts of protein, which, however,
must be supplemented with other protein foods to supply all the
essential amino acids. Tubers are a good source for a variety of
minerals and vitamins. So are vegetables and fruits too.
For the essential amino
acids that the body needs to assemble its own proteins, meat, fish,
and eggs are the best sources. Milk and milk products also provide
abundant protein, phosphorus, calcium and vitamins. Fats and oils
are high in calories but usually contain few nutrients.
The Food and Nutrition
Board of the National Research Council of the National Academy of
Sciences has set dietary standards called Recommended Dietary
Allowances (RDA). These describe the daily amounts of energy,
protein, minerals, and fat-soluble and water-soluble vitamins needed
by normal healthy people from infancy to old age. Doctors say that a
person should eat a variety of foods, maintain ideal a correct
weight, avoid too much fat, saturated fat, and cholesterol, eat
foods with adequate starch and fiber and avoid too much sugar and
sodium to maintain a good healthy body and live a productive life. |
