“Positive health requires a knowledge of man’s primary constitution and of the powers of various tools both those natural and those resulting from human skill. But eating alone is not enough for health. There must be exercise of which the effects likewise be known. If there is any deficiency in food or exercise, the body will fall sick” - Hippocrates- 5th century BC.
Nutrition is the study of how foods, after they are swallowed, make you tick.
Nutrition can determine your zest for life, the good you put into it
and the fulfilment you get from it.
Protein, Fat, Carbohydrates, Vitamins and Minerals are all essential to
life. Water and Fibre are not nutrients but both are essential because
without them metabolism (Chemical Reaction) cannot take place, nutrients
will not be digested and absorbed, and waste matter will not eliminated.
Protein- is made of several amino-acids, out of which 9 of them
are essential in our diet because the body cannot synthesize them.
Protein is required to build new and damaged body cells.
Proteins are found in meat, fish, eggs, milk and other Dairy products. Animal proteins are said to contain the 9 essential amino acids the body need. These amino acids have to be obtained from food because the body cannot synthesize them. Proteins are also found in vegetables such as Soya beans, beans, peas, and nuts; except for Soya beans the vegetable proteins do not possess all the 9 essential amino acids. Vegans can get the required 9 amino acids by combining two or more vegetable proteins in their diet e.g. cereals and nut; whole grains and beans, beans on toast, or by including Soya beans at every meal.
Our body need protein to function properly, therefore good quality and
adequate protein should be eaten daily. This is particularly important
in growing children
Carbohydrates- Our main source of energy is provided by
carbohydrates occurring as sugars and starches: in fruits, milk, grains,
legumes and root vegetables, as well as the obvious sugar, honey and
syrup. Refined carbohydrates e.g. cakes and biscuits, white flour and
sugar provides a lot of kcal. but few nutrients and their consumption
have been linked to tooth decay, heart disease, high blood pressure,
diabetes and obesity.
Fat Although fats are essential in the diet we need only a small amount.
Fats provide a convenient and concentrated source of energy. It also
acts as a solvent for certain vitamins, Vegetable fat is said to be
better than animal fat; cold compressed oil better that solidified oil
like margarine or vegetable shortening. The body needs some fatty acids
but too much fat can form a deposit in the artery wall and raise the
cholesterol level in the blood.
Vitamins-are organic substances which the body requires in small
amounts for its metabolism, yet it cannot make for itself in sufficient
quantities.
Vitamins A D E K B12 are fat soluble vitamins; each consists of closely
related compounds with similar physiological properties.
Vitamins B groups and C are water soluble.
Vitamin A- (retinol) needed for healthy skin and mucous membranes, and
for vision in dim light. Found as such only in animal products, but can
be made in the body from a substance called carotene present in brightly
coloured orange e.g. carrots, or green vegetables.
Deficiency can caused eye irritation, tiredness and night blindness.
Vitamin B group --B1 (thiamine) needed chiefly to metabolise
carbohydrates. The more carbohydrates you eat the more Vitamin B1 is
required. Rich sources of B1 are Brewer’s Yeast, Bran, Marmite, Whole
wheat and brown rice. Deficiency can results in beriberi.
B2 (Riboflavin) –easily destroyed by light. The primary source is milk.
Deficiency- especially in those who do not drink milk can have bloodshot
eyes and cracked or sore lips.
B3- (Niacin or Nicotinic Acid)— found chiefly in Milk and Eggs; Deficiency can cause irritability, nervousness, sever depression and pellagra, a kind of skin disease.
B6 (pyridoxine) is needed particularly, by pregnant women – works best in conjunction with B12 and magnesium. Deficiency shows symptoms such as anaemia, fatigue, depression, nervous disorders and migraine.
B12 – Found mainly in animal products although some sea vegetables
contain a small amount. Unless eggs and dairy products are eaten, a
supplement must be taken. Easily destroyed by heat and light.
Deficiency of both B12 and Folic Acid can lead to pernicious anaemia.
Folic Acid- as the name suggests found in leaves. If plenty of raw
vegetables are eaten deficiency is unlikely. Can be lost during cooking.
Deficiency found in pregnant women and those who take oral
contraceptives. May lead to anaemia and depression
Vitamin C (Ascorbic Acid) - Needed to maintain connective tissue,
protecting and supporting all body cells and for proper absorption of
iron. It helps to prevent disease and also aids in the recovery of
illness especially after an operation. Found in fruits: strawberry,
blackcurrant, citrus and other fruit and green vegetables. It is easily
destroyed during cooking.
Deficiency causes weakening of connective tissue, bleeding of gums,
lower resistance to infection, and slows down healing. Deficiency is
likely unless a fair amount of fruit and vegetables are eaten. The
vitamin is easily destroyed during cooking.
Vitamin D- Needed for absorption of Calcium and Phosphorus. Formed by
the action of sunlight on the skin. Best dietary sources are dairy
products and free range eggs. Deficiency can cause rickets and weakened
or porous bones
Vitamin E—needed for the formation and maintenance of body cells; helps
wounds to heal without the formation of scar tissue: thought to have a
rejuvenating effect. Widely available in food especially cold pressed
vegetable oil, wheat germ, wholemeal flour, eggs and nuts.
Deficiency is rare, but if deficient can cause anaemia and tiredness.
Vitamin K-Helps blood to clot. Widely available in food: vegetables,
cereals and sea vegetables.
Minerals- like vitamins are needed to ensure that the body functions
properly, and for growth and repair of cells. Calcium, Iron, Potassium
and Magnesium are needed in appreciable quantity but others zinc and
iodine needed only in small amounts and are known as trace elements.
Calcium is an important constituent of bones and teeth. For the body to
absorb Calcium, Vitamin D must be present. Good sources of Calcium are
dairy products and egg yolk. Deficiency can lead to rickets and in
children also stunted growth.
Magnesium- The whole adult body contains Magnesium. The greater part of
this mineral is in the bones in combination with phosphorus and
bicarbonate. It is also found in the soft tissue where it is mainly
bound to protein.
Phosphorus- Phosphorus is also needed for the bones, but is also
involved in a various chemical reactions. It is an important anion of
the cells. It is an essential component of nuclei acid. Widely available
in food and deficiency is unknown.
Iron - a major portion of iron is found in the haemoglobin of the blood.
It is a pigment present in red muscle, which can easily take up and give
off oxygen; in the cellular enzymes iron porphyrins, the most important
being the cytochromes. Food rich in iron are Liver, Meat, molasses,
wheat germ, egg yolk, spinach, whole flour and yeast extract. Vitamin C
aids in the absorption of iron. Deficiency leads to tiredness and
anaemia.
Sodium and Potassium- are often treated together, since balance between
them is important. They act together to regulate water fluid and the
amount of water retained. Sodium is adequately supplied from food even
without the addition of table salt.
Deficiency is rare except in cases such as heatstroke salt can be lost through perspiration. Excess of salt in the diet is more common which can lead to high blood pressure and stroke.
Potassium is found in most food but deficiency can occur when little raw
fruit and vegetables are eaten and when the diet is too high in salt.
Then hypoglycaemia (low blood sugar) may occur.
Besides the above minerals, the body also require tiny amount of other
elements, called trace elements: iodine, zinc, selenium, copper, cobalt,
sulphur.
Iodine- is essential for correct functioning of thyroid. Only minute
quantity is required. Most reliable sources are sea vegetables, onion
and watercress. Nuts and unrefined oil also contain iodine. Even slight
deficiency can lead to thyroid disease and high level of blood
cholesterol and affect mental and physical development.
Fibre or Roughage—Food which contains fibre and cellulose, together
termed roughage are not digested by enzymes or bacterial activity; it
enters the colon as a semi- solid consistency and stimulates peristalsis
(movement of food in the stomach) by its bulk and by its mechanically
irritating properties. All refined food: white flour, white rice, peeled
potatoes and other root vegetables can lose the bran or cellulose during
processing or preparation. Fresh and cooked fruit and vegetables are
good sources of roughage.
Water-The body of an average man consists of 40 litres of water: 25
litres within the cells and 15 litres in the cellular fluids. The water
intake comprises of the fluid drank and the fluid in the food eaten. It
will be seen that the water and the fluid drank is equivalent to the
water excreted, in the urine, faeces and perspiration. Therefore,
especially in hot weather sufficient water should be replaced daily for
bodily functions.
ENERGY
Food is needed not only for building and repairing body tissue but also
to provide energy to run the functions in the body and to maintain body
temperature. Energy produced by food is measured in Kilocalories (kcal.)
or Kilojoules (kjoules). 1 gram of protein provides 4 kcal; 1 gram of
carbohydrate provides 4 kcal; and 1 gram of fat provides 9 kcal. The
energy requirement of an individual depends on 4 variables: Body size
and composition, Age, Climate and environment, and Physical Activity.
The body weight of an individual depends on the balance of energy
obtained from food and the energy used during physical activity.
Excessive intake of food, especially fatty ones increases the kcal. in
the body. Unless this is counter balanced by physical exercise it will
lead to ill health such as obesity followed by other complications.
EXERCISE
The value of physical exercise is certainly underestimated. Exercise
helps to balance the kcal. intake; it helps to tone the muscles; and
aerobic exercise gives you a good supply of oxygen which is important
for the oxidation of food.
In modern lifestyles people lead very sedentary lives; and also the urban and industrial life somewhat restricts them from engaging in physical activities. This is due to the fact that everybody has to get to work in cars and buses, and people have to work so hard that they do not have any recreation time. (Health is the most important thing in life so you have got to make time).
Walking is the mildest of exercise and thirty minutes to an hour walk three or four times a week will help you towards a healthy life.
The importance of physical exercise in immunity to heart disease is shown by Masai people in East Africa. Because of their active life style the men are almost free of coronary artery disease, although their diet contains a large amount of animal fats. Their maximum oxygen uptake is comparable to that of Olympic athletes. (Study by Mann et al 1965)