What You Need to Know About Nutrients
Every day your body needs certain
that it cannot
manufacture for itself.
They provide energy, build and repair body tissues, and regulate body
The six classes of essential nutrients, which are discussed in this
section, are water, protein, carbohydrates, fats, vitamins, and minerals
Water makes up about 60 per cent of our body and is essential for health and
Besides water, we also need energy to live, and we receive our energy from the
carbohydrates, proteins, and fats in the foods we eat.
These three essential nutrients are called
, because they
are the nutrients required by the human body in the greatest amounts.
The amount of energy that can be derived from the macronutrients is
There are nine calories in every gram of fat
Four calories in every gram of protein or carbohydrate.
The other two essential nutrients - the vitamins and minerals - are called
because our bodies need them in only very small
In the latest report of the National Academy of Sciences, the agency that
establishes nutrient intake recommendations for the United States and Canada,
adults should get
45 to 65 per cent of calories from carbohydrates,
20 to 35 per cent from fat
and 10 to 35 percent from protein.
Children’s fat intake should be slightly higher: 25 to 40 per cent of their
Water makes up 85 per cent of blood, 70 per cent of muscles, and about 75 per
cent of the brain,
Performs many essential functions:
It carries nutrients, maintains temperature, lubricates joints, helps with
digestion, rids the body of waste through urine, and contributes to the
production of sweat, which evaporates from the skin to cool the body.
You lose about two to 2.5 litres of water a day - the equivalent of eight to
10 cups (250 ml)
- through perspiration, urination, bowel movements,
and normal exhalation. You lose water more rapidly if you exercise, live
in a dry climate or at a high altitude, drink a lot of caffeine or alcohol
(which increase urination), skip a meal, or become ill.
To assure adequate water intake, we need approximately two to three
litres (eight-12 cups) of fluid each day.
Critical for growth and repair,
form the basic framework for our
muscles, bones, blood, hair, and fingernails.
Supplying four calories per gram, they are made of combinations of 20
, nine of which we must get from our diet because the human body cannot
produce them. These are called
essential amino acids.