1. Carbohydrates
Carbohydrates can be grouped into two categories:
simple and complex. Simple carbohydrates
are sugars whereas complex carbohydrates consist of starch and dietary fibre. Carbohydrate
provides about 4 kcal (kcal = kilocalories = Calories) per gram (except for fibre) and is the energy that is used first to fuel muscles
and the brain. Soluble fibre (fruits, legumes, nuts, seeds, brown rice, and oat,
barley and rice brans) lowers blood cholesterol and
helps to control blood sugar levels while providing very little energy. Insoluble fibre
(wheat and corn bran, whole-grain breads and cereals, vegetables, fruit skins,
nuts) doesn’t provide any calories. It
helps to alleviate digestive disorders like constipation or diverticulitis
and may help prevent colon cancer. Most
calories (55-60%) should come from carbohydrates. Sources of carbohydrates include grain
products such as breads, cereals, pasta, and rice as well as fruits and
vegetables.
2. Protein
Protein from food is broken down into amino acids
by the digestive system. These amino acids are then used for building and
repairing muscles, red blood cells, hair and other tissues, and for making
hormones. Adequate protein intake is
also important for a healthy immune system.
Because protein is a source of calories (4 kcal per gram), it will be
used for energy if not enough carbohydrate is available due to skipped meals,
heavy exercise, etc. Main sources of
protein are animal products like meat, fish, poultry, milk, cheese and eggs and
vegetable sources like legumes (beans, lentils, dried peas, nuts) and seeds.
3. Fat
The fat in food includes a mixture of saturated and
unsaturated fat. Animal-based foods such
as meats and milk products are higher in saturated fat whereas most vegetable
oils are higher in unsaturated fat.
Compared to carbohydrate and protein, each gram of fat provides more
than twice the amount of calories (9 kcal per gram). Nevertheless, dietary fat does play an
important role in a healthy diet. Fat
maintains skin and hair, cushions vital organs, provides insulation, and is
necessary for the production and absorption of certain vitamins and
hormones. Nutrition guidelines state
that Canadians should include no more than 30% of energy (calories) as fat and
no more than 10% of energy as saturated fat.
4. Vitamins
Vitamins
help to regulate chemical reactions in the body. There are 13 vitamins, including vitamins A,
B complex, C, D, E, and K. Because most
vitamins cannot be made in the body, we must obtain them through the diet. Many people say that they feel more energetic
after consuming vitamins, but vitamins are not a source of energy
(calories). Vitamins are best consumed
through a varied diet rather than as a supplement because there is little
chance of taking too high a dose.
5. Minerals
Minerals
are components of foods that are involved in many body functions. For example,
calcium and magnesium are important for bone structure, and iron is needed for
our red blood cells to transport oxygen.
Like vitamins, minerals are not a source of energy and are best obtained
through a varied diet rather than supplements.
6. Water
Water
is a vital nutrient for good health.
Most of our body weight (60-70%) is made up of water. Water helps to control our body temperature,
carries nutrients and waste products from our cells, and is needed for our
cells to function. It is recommended
that adults drink 8 glasses of fluid daily (or more in hot weather or during
physical activity). This fluid does not
have to be water alone. It can also be
obtained from juice, milk, soup, and foods high in water such as fruits and
vegetables. Caffeine-containing
beverages (coffee, tea, cola) don't count because caffeine is a diuretic,
making us lose water. A great plus for
water in comparison to the other fluids is that it hydrates our body without
extra calories.
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