Nutritional Needs of the Human Body

Eating patterns, influenced by many factors have a direct effect on nutrition. Taste preferences, healthy status and various social and cultural customs are some of the factors that determine what food a person eats. The food we eat should provide the body with all essential nutrients required to grow; proteins build and may maintain body cells and some may be converted into energy.

Fresh raw fruits and vegetables are generally more nutritious than cooked or processed food. Nutrients especially the B complex vitamins and vitamin C are lost during cooking and storage. Fresh fruits are good source of vitamins and minerals, especially vitamin A and C and of carbohydrates in the form of cellulose and natural sugar .fresh fruits are also refreshing because they contain a lot of water.

Yellow fruits such as mango pawpaw are good source of carotene, which is converted into vitamin A. Other fruits such as bananas and apples contain valuable bulk fibre which helps regulate bowel movements; some fruits are also good source of mineral salt.
Vegetables provide vitamin, mineral and bulk to the diet. Their flavour color and texture appeal to the appetite. Light green vegetables provide vitamins, mineral and large amount of carbohydrates especially as cellulose, which is digestible but important as dietary fibre. Yellow and dark green vegetables are excellent source of vitamin A. vegetable leaves are generally rich in calcium, iron, magnesium and vitamin B and C.
To be meaningful, information, on the nutrient levels in fruits, nuts and other foodstuffs must be related to the usefulness of the nutrients in terms of the need for those nutrients by the body. Energy, protein, water, dietary fibre, vitamins and minerals are all essential for one long-time well being.
Carbohydrates and fats are the body’s primary source of energy; they supply the fuel necessary for the body heat and work. Their fuel potential is expressed in kilojoules’ or kilocalories. These signify the amount of chemical energy released when food is digested. Metabolism is the term for the way the body changes the energy contained in food into various forms. When food is not available, the body draws on its stores to meet energy needs; glycogen form carbohydrate store.
The relationship between body energy balance and body weight determines whether persons are more or less a healthy weight for their age and height or they suffer from the problem of overweight. Being too fat is usually a result of more energy in-put than energy out-put. Extreme weight loss results from a deficit of energy in-put in relation to energy requirement. Energy requirement vary with age, sex, weight level of physical activities and genetic variation.
One of the commonest causes of malnutrition is a deficit in energy balance where people do not eat foods of all kinds. In many areas food shortages are seasonal, being most severe at the end of the dry season and at the beginning of the rains.
Oil-rich seeds and some fruits can play a role in addressing the energy needs of rural population on a large scale. Avocado and pumpkin are example of fruits that are important sources of energy; not getting enough energy and nutrients is not always simply a result of not enough food being available; lack of variety in diet may also result in dietary deficiencies.
A varied diet is a result likely to be a well balanced are more important, usually different foods even in small qualities improves the flavour of the staple food and thus tends to increase overall consumption. Dietary deficiencies and food insecurity are strongly related to the decreasing diversity of traditional diets. Using fruits and nuts in preparing various deities adds variety to the diet and may improve the appetite.

Carbohydrates supply most of the people of the world with their primary source of energy, and as a product of photosynthesis, carbohydrate are widely distributed in nature and their food products are easy to store and generally low in cost. The principal carbohydrates present in foods are sugars, starches, and cellulose. Sugars are commonly divided into simple sugars and complex sugars; simple sugars such as those found in honey and fruits are easily assimilated by the body. Complex sugars such as those found in whole grain starches require prolonged enzymatic action to break them down into simple sugars (glucose) for absorption in the gut.
Carbohydrate foods also prevent the breaking down of both fats and protein to supply energy, which would otherwise result in excessive production of toxic metabolic by-products.

Fats and Proteins:
Fats or lipids are the most concentrated source of energy in the diet and when oxidized they furnish more than twice the number of calories per gram as carbohydrates or protein. In addition, fats act as carries for the fat soluble vitamin A, D, E, and K. Fats deposits surround, protect and hold in place organs such as the kidney, heart and liver. A layer of fat also insulates the body from temperature change in the environment and prevents body heat. It aids in transmitting nerve inputs, producing metabolic precursors, forming cell membrane structure and transporting other molecules such as protein. Fats prolong the digestion process by slowing down secretion of hydrochloric acid in the stomach, hence creating a long feeling satiety after meal.
Fats are composed of glycerol and attached fatty acids of various lengths and degree of saturation. Essential fatty acids are long chain un-saturated fatty acids that cannot be manufactured by the body. The major one is linoleic acid. Its faction includes improving skin integrity, lowering serum cholesterol levels and prolonging clotting time.
The type and amount of dietary fat can affect health; large amounts of saturated fats and cholesterol increase the risk of cardiovascular diseases and other general health problems. Too little fat can result in a deficiency of the essential fatty acid and linoleic acid. When fat provide 10% or less of total kilocalories deficiency symptom occur.

Although protein also yields energy, their main job is building and rebuilding body tissues and amon-acids are the structural components of proteins. There are 22 in total, 9 of which the body cannot synthesize in adequate amount, and these 9 are called essential amon-acids. Food proteins are considered complete when they contain the 9 EAAs in appropriate amount. Animal proteins are complete, while vegetable proteins are usually incomplete, but be mixed with complete proteins or with each other to provide all 9 EAAs for day.
In case of fasting or starving proteins are broken down for energy; thus dietary carbohydrate as mentioned earlier, have a protein sparing effect. Protein requirement are influenced by the growth needs and rate of protein synthesis, the protein quality of food, dietary carbohydrate and fat levels.
Water and dietary fibre
The average adult metabolizes 2.5 to 3 liters of water each day and the body water performs these essential functions.
• It helps give structure and form to the body through the turgidity it provides to the tissues cells.
• It creates the water based environment necessary for the vast array of the chemical reactions and reaction that comprise the body’s metabolism and sustain life.
• Improves the means for maintaining stable body temperature.
Water intake and output must be in constant balance; abnormal condition such as diarrhea produces much greater loss than normal. Extensive loss of body fluids can be especially dangerous in infants and children. Their bodies contain a greater percentage of water, and much more of the water is outside the cells and easily available for loss.
Dietary fibre
Fibre is the non digestible naturally occurring natural in food that forms its bulk and is necessary for intestinal action and waste elimination. Dietary fibre consists of
• Cellulose found in the skin of fruits and vegetables
• Non-cellulose polysaccharides (hemicelluloses, pectin, gums, mucilage, and algal substance)
• Lignin which is the only non-carbohydrate type of dietary fibre.
Among the health benefits offered by dietary fibre are that binds bile acids to form insoluble compounds; thus preventing their absorption.
Vitamin is other vital organic dietary substances in addition to carbohydrates, fats, and proteins. They are usually necessary in only very small amount to perform a particular metabolic function or to prevent an associated deficiency disease. They cannot be manufactured in the body and must be supplied in the food.
Vitamins are grouped and distinguished according to their solubility infant or water. Those that are fat soluble are vitamin A.D, E and K. They can be stored in body fat and water soluble vitamins are C and B complex family. They cannot be stored in the body in the same way fat soluble vitamins.
Vitamin A.
Fat-soluble vitamin A occurs in nature in two forms; preformed vitamin A (common in certain animal tissues) and pro-vitamin A (carotenes).
Vitamin A aids in growing and repairing body tissues and helps maintain a smooth, soft and disease free skin. It protects the mucous membranes of the throat, nose and lungs, and reduces susceptibility to infections.
It is essential for good night vision, and prompts the secretion of gastric juice, important for digestion proteins. Yellow fruits and vegetables, as well and dark green leaves are good source of these also help provide this vitamin. Fats, protein and zinc help the body absorb and use vitamin A; and thus a diet low in these nutrients can contribute to vitamin A deficiency low levels of vitamin A can lead to partial or complete blindness, and children who lack vitamin A are more likely than healthy children to die from infections diseases. Severe deficiency results also in rough dry skin, loss of the sense of smell, and lack of hair insure and sheen.
Vitamin B1 (Thiamine)
Thiamine is a water soluble vitamin that acts as a co-enzyme in converting glucose to energy and it is heat sensitive. Thiamine maintains nervous system health, improves mental stability and improves individual learning capability. It also improves appetite and food assimilation and digestion. Thiamine is common in the germ and brain of most gains and in some fruits and vegetables.

Deficiency of thiamine results in beriberi associated with malnutrition where beriberi causes confusion and loss of memory, loss of appetite, general body weakness, tiredness, abdominal pains heart irregularities and diseased conditions.
Vitamin B2 (riboflavin)

Vitamin B2 is also a water soluble vitamin occurring naturally in foods containing other forms of vitamin B2. It is stable to heat and oxidation, and functions as part of a group of enzymes that are involved in breaking down using carbohydrates, fats, and proteins. It is also important for respiration and for maintaining good vision, skin, nails and hair. Many green foods, especially leaves are a good source of this vitamin and wild leafy vegetables have sometime been found to have significantly higher riboflavin content than cultivated vegetable varieties.

The deficiency is usually marked by sores and cracks in the corner of the mouth and red and sore tongue, eye fatigue, dilation of the pupils, skin disorders, sluggishness, and dizziness and inability to urinate.
Niacin (nicotinic acid)

Niacin is a member of the vitamin B complex and is water soluble and more soluble than thiamin and riboflavin, especially to heat, light, and air. It is assists in breaking down and utilizing proteins, fats, and carbohydrates. It improves blood circulation by reducing cholesterol levels and is necessary for synthesizing sex hormones and forming and maintaining healthy skin. It is commonly found in peanuts, and wheat germ.

Severe deficiency results in pellagra characterized by diarrhea, rough skin, and nervous disorder, inflammation of the mucous membranes, mouth and intestinal tract, muscular weakness, indigestion, skin eruptions and general fatigue.
Vitamin C (ascorbic acid)

Vitamin C is water soluble vitamin; it helps maintain collagen responsible for, a protein for forming connective tissues, ligament and bones. It plays a role in healing wounds, forming red blood cells and preventing hemorrhage. It boosts the ability to fight off infection hence its use for preventing and treating colds. The major source of vitamin C is fresh fruits and vegetables, especially citrus, tomato, cabbage and Amaranthus (Dodo).

Severe deficiency of vitamin C results in scurvy and other related disorders including shortness of breath, impaired digestion, bleeding of gums, swollen and painful joints, lowed resistance to infection, anemia and slow healing of wounds.
It is important for a rural person to understand the value of nutrition. Despite the fact that food is available, they usually have poor diet which in turn affect their level of development. Many diseases result and reduce their production level.


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