Nutrition
We are made up of what we eat. We live on what we eat.
Your Body is just like a Factory
Food is the fuel that keeps it running.
Your food contains:
1. Carbohydrates: They provide the power needed to run the factory.
2. Fats: They are storage bins, storing the energy derived from food.
3. Proteins: They are building blocks used to repair and expand the factory.
4. Vitamins: They are the workers, helping to release energy from fats,
proteins and carbohydrates.
5. Minerals: They are the carpenters, they help build bones and teeth.
Role of Carbohydrates
The main role of carbohydrates in our diet is to produce energy. Each gram of
carbohydrates provides us with about four calories. Carbohydrates also act as a
food store. Our bodies also store carbohydrates in insoluble forms as glycogen
or starch. This is because these two carbohydrates are compact. Carbohydrates
are also combined with nitrogen to form non-essential amino acids.
In plants, carbohydrates make up part of the cellulose, giving plants strength
and structure.
Role of Fats
Although there are fewer types of fats than carbohydrates, fats produce more
than twice as much energy as carbohydrates. Being a compact fuel, fat is
efficiently stored in the body for later use when carbohydrates are in short
supply. Fats are necessary, but only in small amounts. They are used for growth
and repair, cushion our bones and internal organs, and provide some insulation
against the cold. Besides, fats help give foods a smooth, rich taste.
Do you know that animals need stored fat to tide them over in dry or cold
seasons, as do humans during times of scarce food supply?
We also need fats to transport fat-soluble vitamins into the body. Fat-soluble
vitamins include A, D, E and K, and these vitamins are not water soluble.
Some other lipids also serve the function of helping blood clot and helping the
transmission of nerve pulses throughout the body. Cholesterol makes our skin and
hair smooth, preventing them from drying up, and helps in the formation of
Vitamin D.
Animal fats can be found in such foods as:
Role of Proteins
We need protein to grow and for repairs. Proteins are used to make our body
cells. Specifically, they are used in the formation of new protoplasm.
Antibodies, enzymes and hormones are also made of proteins. Finally, proteins
provide us with energy.
Protein can be found in such foods as:
Role of Vitamins
Vitamins, on the other hand, are a group of organic substances quite
unrelated to each other in their chemical structure. Some common features shared
by all vitamins are that they are not digested or broken down for energy, they
are not built into body structures, they are essential in very small quantities
for normal health, and that they are needed for chemical reactions in the cells,
working in association with enzymes. Some vitamins and enzyme partners help to
form body parts such as bones, body tissues, blood cells, and the body genes.
Some vitamins help in forming the body’s defense against disease-causing
bacteria and viruses.
Each vitamin has a chemical name and a letter. For example, vitamin C is also
known as ascorbic acid. Fat-soluble vitamins include A, D, E and K. There are
nine other vitamins which are water soluble: vitamin C and eight B vitamins:
thiamin (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5),
pyridoxine(B6), folacin, cobalamin (B12) and biotin.
Different foods contain vitamins. Fruits contain Vitamin C. Vitamin K can be
found in leafy vegetables and many other foods. Animal foods contain Vitamin A
and D. Vitamin B is present in vegetables and meat.
Do you know that we can obtain Vitamin D from the sunlight?
Role of Minerals
Minerals are inorganic mineral nutrients like:
Iron
Calcium
Sodium
Magnesium
Iodine
Our bodies cannot make these materials, but require them for structural
composition of hard and soft body tissues. When we take in iron or other
minerals, we do not take them in in their original solid form, but rather in
irons.
These mineral nutrients, all of which must be supplied in the diet, are of two
classes: the major elements such as calcium, phosphorus, magnesium, iron,
iodine, and potassium; and trace elements such as copper, cobalt, manganese,
fluorine, and zinc. We need to eat larger amounts of the major elements, but
require only small amounts of the trace elements. Still, we need all the
minerals.
Minerals are used as building materials in the body, and they participate in
body processes. For example, iron is a component in the blood and carries
oxygen. Calcium is needed for developing the bones. Phosphorus combines with
calcium in the bones and teeth. Zinc is also important in forming enzymes.
Energy
Energy is measured in joules or calories. Both units are very small. So when
talking about the energy value of food and the energy output of body activities,
we multiply the values by one thousand (kilo=1000) and refer to them as
kilojoules or kilocalories. Kilocalorie is often abbreviated to Calorie spelled
with a capital C. (A kilocalorie is defined as the heat energy needed to raise
the temperature of 1 kilogram of water from 14.5° to 15.5° C (58.1° to 59.9°
F).) We usually use a Calorimeter to measure the energy content of food
substances.
For conversions,
1 kJ = 0.24 Cal
1 Cal = 4.2 kJ
Energy is found in carbohydrates, fats and proteins. Carbohydrates are the most
abundant foods in the world, and fats are the most concentrated and easily
stored fuel. If the body exhausts its available carbohydrates and fats, it can
use proteins directly from the diet or break down its own protein tissue to make
fuel.
Average values of energy-yielding constituents
One gram carbohydrates = 3.75 Calories (16 kJ)
One gram proteins = 4 Calories (17 kJ)
One gram fat = 9 Calories (37 kJ)
One gram alcohol = 7 Calories (29 kJ)
Water
Water is a good solvent for many chemicals; hence it is used in the transportation of many substances, and in many chemical reactions happening in the body. It carries oxygen, nutrients, carbon dioxide and other waste products. It also transports hormones and enzymes. Water acts as a cushion and protects important body organs and it lubricates the joints. Your eyes are kept wet by water when you blink, thus preventing them from drying up. Your skin also needs water. Water makes it soft and prevents it from drying and cracking. Water also keeps the body temperature normal. Water can play an important role in keeping you alert, and is essential to make your brain work better. In summary, your entire body needs water.
This information comes from the Home and Garden Bulletin No. 72, available from Supt. of Documents, U.S. Government Printing Office, Washington, DC 20402