Basic Definition
Ø What is food? Food is
any nutritious substance that humans and animals eat or drink or that plants
absorb in order to maintain life and growth. In other words, food is any
substance consumed to provide essential nutrients for man and animals.
Ø What is nutrition? Nutrition
is the process of taking in nutrients from the foods we eat. In other words,
nutrition is the study of relationship between the food we eat and the
composition of the essential nutrients therein. It is these essential nutrients
contained in the food we eat that form what is popularly termed, ‘Classes of Food’ or ‘Components of Nutrition’
Classes of
Food
The food we eat can be classified into six (6): These
classifications are based on their nutritional components.
They are as follows:
Carbohydrates
Carbohydrate foods are primary
source of energy to the human body. Carbohydrates are made up of sugar, starch
and dietary fibres.
Major Sources of Carbohydrates
1. Sugar
and sugary products: This includes refined sugar, carbonated soft drinks,
other industrial products with sugary contents.
2. Natural
starchy foods: This includes yam, cassava foods, cocoyam, rice etc.
3. Soluble
fibre: This includes brown rice, barley, oat, legumes, fruits, nuts
etc.
4. Insoluble
fibre: This includes wheat, corn, whole grain bread, cereals,
vegetables, fruit skins etc.
Major Functions of Carbohydrates
i.
Supply of energy to fuel muscle and brain functions;
ii.
Dietary fibre, which is a component of carbohydrate
helps to control blood sugar levels and cholesterol in the blood stream;
iii.
Some carbohydrate sources can as well help to
alleviate digestive disorders like constipation, and may also help to prevent
colon cancer.
Protein
Proteins are
body-building nutrients contained in the food we eat. In practice, protein from
food is broken into amino acids by the digestive system, which is then used in
the body-building processes.
Major Sources of Protein
1. Animal products: This includes
meat, fish, poultry, egg etc.
2. Dairy products: This
includes milk, cheese etc.
3. Legumes and seeds: This
includes beans, lentils, dried peas etc.
Major Functions of Protein
i.
Building of muscles and tissues needed for growth and
development of children;
ii.
Repairing of worn-out tissues;
iii.
Important for a healthy immune system as it supports
the white blood cell;
iv.
Where carbohydrate is not adequate, protein supplies
supplementary energy to the body.
Fats
Fats are energy
giving nutrients found in the food we eat.
Major Sources of Fat
1. Saturated
fat: This is found mainly in animal-based foods such as meat,
milk products, poultry, fish etc. meanwhile, poultry and fish have less
saturated fat. Tropical oils such as coconut oil, palm oil and cocoa butter are
more or less saturated.
2. Unsaturated
fat: This is mainly found in vegetable oil.
Major Functions of Oil
i.
Maintenance of skin and hairs;
ii.
It cushions vital organs;
iii.
It provides insulation;
iv.
It is necessary for the production and absorption of
certain vitamins and hormones;
v.
It is a good source of energy to the body
Vitamins
Vitamins are
vital nutrients that help in the normal growth and development of the body and
its component systems. They are very essential to normal body metabolism.
There are 13 forms of vitamin, which are grouped under the
following:
·
Fat-soluble vitamins: These are
vitamins that are stored in the fatty tissues of the body and the liver. They
can stay in the body as reserves for days or even months. They are absorbed
through the intestinal tract with the help of fats (lipids). Examples of
fat-soluble vitamins are Vitamins A, D, E and K.
·
Water-soluble vitamins: This group
of vitamins does not get stored in the body for long- they soon get excreted in
urine. Because of this, water-soluble vitamins need to be replaced more often
than fat-soluble vitamins. Vitamins C and all B Complex vitamins are in this
group.
Major Sources of Vitamin
1. Vitamin
A: This is a fat-soluble vitamin with the chemical names, retinol,
retinal, carotenoids etc. Here we have foods like carrot, sweet potato,
spinach, egg, milk, butter, broccoli, cold liver oil etc
2. Vitamin
B: This is a water-soluble vitamin with the chemical name thiamine.
Common food sources include pork, yeast, brown rice, cauliflower, oranges,
liver, eggs, cereal grains etc.
3. Vitamin
B2: A water-soluble vitamin with the chemical name riboflavin.
Common food sources include bananas, okra, milk, yogurt, meat, fish, eggs,
green beans etc.
4. Vitamin
B3: A water-soluble vitamin with the chemical name nuacin
or niacinamide. Common food sources include liver, kidney, salmon fish,
avocados, dates, tomatoes, leafy vegetables, asparagus, mushrooms, carrots,
nuts, whole grains, chicken, beef, broccoli etc.
5. Vitamin
B5: A water-soluble vitamin with the chemical name pantothenic
acid. Common food sources include meat, whole grains, fish ovaries,
avocados, royal jelly etc.
6. Vitamin
B6: A water-soluble vitamin with the chemical names, pyridoxine,
pyridoxamine, pyridoxal. Common food sources include vegetables,
nuts, bananas, meats, whole grains etc.
7. Vitamin
B7: A water-soluble vitamin with the chemical name biotin.
Common food sources include egg yolk, liver, some vegetables etc.
8. Vitamin
B9: A water-soluble vitamin with the chemical names folic
acid, folinic acid. Common food sources include leafy vegetables,
legumes, sunflower seeds, liver, bakers’ yeast etc.
9. Vitamin
B12: A water-soluble vitamin with the chemical names cyanocobalamin,
hydroxocobalamin, methylcobalamin. Common food sources include
eggs, fish, poultry, dairy products, soy products, milk etc.
10. Vitamin
C: A water-soluble vitamin with the chemical name ascorbic
acid. Common food sources include fruits and vegetables.
11. Vitamin
D: A fat-soluble vitamin with the chemical names, ergocalciferol,
cholecalciferol. Common food sources include early morning sun light,
fatty fish, beef liver, mushrooms etc.
12. Vitamin
E: A fat-soluble vitamin with the chemical names tocopherols,
tocotrienols. Common food sources include almonds, avocados, eggs, milk,
nuts, unheated vegetable oils, leafy vegetables, whole grains, kiwi fruit etc.
13. Vitamin
K: A fat-soluble vitamin with the chemical names phylloquinone,
menaquinones. Common food sources include leafy green vegetables, kiwi
fruit, avocados etc.
Major Functions of Vitamin
i.
Vitamin A promotes skeletal growth, normal teeth
structure, healthy mucous membranes, healthy skin, eyes and hair; also
essential for night vision;
ii.
Vitamin D promotes bone and tooth development and
normal growth; maintains nervous system, prevents rickets and aids in the
utilization of phosphorus and calcium;
iii.
Vitamin E prevents loss of other vitamins, aids blood
flow to the heart, lowers blood cholesterol, strengthens capillary walls etc;
iv.
Vitamin B1 helps convert sugar and starch into energy,
promotes digestion, prevents fatigue, promotes strong heart muscles etc;
v.
Vitamin C is essential for the formation of collagen,
aids in metabolism of amino acids and calcium, stops internal bleeding,
strengthens blood vessels, reduces allergies, heals wounds and burns etc;
vi.
Vitamin K reduces risk of menstrual pains and internal
bleeding.
Minerals
Minerals are essential
nutrients that are needed in small amounts to keep our body healthy. There are
lots of minerals that are contained in the various foods we eat, which form the
major sources of minerals in our body.
Major Sources of Mineral
1. Calcium-concentrated
foods: These include milk, cheese, yogurt, salmon fish, spinach,
cashews, brown rice, avocados, beans, carrots, garlic, apricots, calcium-fortified
orange juice, calcium-fortified beverages etc.
2. Iron-concentrated
foods: These include poultry, meat, soybean, bananas, carrots,
grapes, cucumber, unripe plantain, lentils, nuts, liver, iron-fortified grain
products, cereals, sweet peppers, strawberries etc.
3. Magnesium-concentrated
foods: These include spinach, dried beans, cereals, chicken,
cashew, pumpkin, sunflower, nuts, green vegetables, pineapple etc.
4. Potassium-concentrated
foods: These include banana, pawpaw, sweet potato, avocado, tomato,
orange juice, milk, pineapple, cucumbers, lemons, yogurt, beef, fish, almond
etc.
5. Zinc-concentrated
foods: These include yogurt, milk, mushrooms, seafood, cheese,
dried beans, lentils, soybean, poultry, fish, liver, kidney, sunflower etc.
6. Others
include Chromium(corn oil, cheese, whole grains etc), Copper(soy
bean, bone meal, raisins etc), Iodine(oranges, grapes, lettuce etc), Manganese(egg
yolks, whole grains, pineapple etc), Phosphorus(mushrooms, carrots, oats etc),
Sodium(raw milk, okra, pumpkins etc), Sulphur(onions, broccoli, egg etc).
Major Functions of Mineral
i.
Calcium builds bones and teeth and helps keep them
strong; it also slows down bone loss as one gets older. People with
osteoporosis need a daily intake of say 1200 mg of calcium either through food
or supplement etc.
ii.
Pregnant women need extra iron to meet their own and
baby’s needs; Iron prevents one from being tired; it helps to carry oxygen to
all parts of the body etc.
iii.
Magnesium keeps nerves and muscles strong; it also
helps in teeth and bone formation in infants etc.
iv.
Potassium keeps fluids balanced in blood and tissue;
it helps in controlling blood pressure; it also allows nerves and muscles to
work together etc.
v.
Zinc is needed for growth and development of essential
organs including reproductive organs; it helps to maintain a healthy immune
system; it is very important for wound healing; it also helps the body use
other nutrients.
Water
Water is the vital
nutrient for good health. Our body weight is more of water (between 60%-70%).
Major Sources of Water
1. Natural
drinking water: This is the natural water we drink usually to quench our
thirst.
2. Juice and
industrial liquids: These include water from different kinds of juice and
carbonated drinks such as Coca Cola, Orange juice, Pineapple juice etc.
3. Foods: This
includes soup, tea, coffee etc.
4. Raw fruits
and vegetables: These include orange, pineapple, watermelon, pumpkin, mango,
pawpaw etc.
Major Functions of Water
i.
Water helps to control our body temperature
ii.
It helps to carry nutrients and waste products from
our cell;
iii.
It is needed for the proper functioning of the cell
iv.
Water helps to hydrate
our bodies without extra calories
v.
Water is so vital for our life and health that it has
been recommended that every adult have an intake of no less than 8 glasses of
water (made up of different water sources) daily. More is needed during hot
weather or during physical activity.
Conclusion
Our life and health depends so much on what we eat. Hence,
this article is not only for examination purpose, but should be practically
applied by learners and readers of this post in making their lives better.
*** Mind you, if you are faced with health challenges or in need of expert medical advice, please consult your doctor...
