FOOD AND NUTRITION 

Introduction :

Food and nutrition is a field of biochemistry which deals with the nutrients and caloric requirement of the living body.It deals with the effect on growth and metabolism of the living system arising from the imbalanced diet.For instance the statistical survey data of food and nutrition showed that 30 % population was suffering from the disease of malnutrition Diseases like decayed and crocked teeth, bone deformation,lack of mental alertness and under weight were real outcome of the unbalanced food and diet.

Classification :

The food is required by the body to achieve three purposes. 

(a) Energy 

(b) Growth and maintenance of tissues 

(c) Regulation of body processes and for the sake of simplicity

It is classified into six groups: 

(i) Carbohydrate

(ii) Lipids and fat

(iii) Proteins

(iv) Vitamins

(v) Minerals 

(vi) Water 

Elements of Nutrition :

For healthy performance, each day the diet must supply the body with:

1. Adequate calories 
2. Vitamins  
3. Mineral Salts
4. Water 
   

It becomes therefore necessary to choose foodstuff in a diet which can cover all the above needs of the living system and such diet is known as a balanced diet.A malnutrition or bad nutrition is a state in which body is poorly nourished  due to long use of a diet which lacks in essential elements and becomes subject to deficiency diseases and other disorder.

     The energy and the fuel value of foods which supply this energy is measured in calories.In nutrition,the use of large Calorie (written in capital C) or kilo calorie is employed and is equal to amount of heat required ti raise the temperature of 1 KG of water by 1C.

    An energy requirement for a person of normal size and wright, working under moderate conditions of climate may vary around 2500-3000 calories depending upon the nature of job.Concentrated brain work.for example,study and office work require no additional calories. Comparatively young persons need more calories than the older ones.

   The energy expenditures in some typical pursuits are given below (in calories per hour) :

• Walking at 3.75Km p.h                           140
  
• Walking at 6.Km p.h                               240
  
• Sawing food                                            450
• Masonry Labor                                       270
• Sweeping and cleaning                           100
• Dish washing/Sewing                              70
• Concentrated Brain Work                        Nil
  

Almost all the physiological activities of the body are energy dependent and this comes from the break down of carbohydrate,fats and proteins the there major nutrients.Carbohydrate and to lesser extent fats are the cheaper sources of the calories than the proteins.Nevertheless the proteins are primarily necessary for the tissue growth and repair but if intake of other two sources of calories are insufficient then protein is also burned for energy.

The Quantity of food needed to provide required calories for an individual could be calculated as follows :

1. Carbohydrate give          4 per gram
2. Fats give                          9 calories per gram
3. Proteins give                   4 calories per gram

Carbohydrate Intake:

Carbohydrates are a cheap and efficient source of energy for animals. They serve as the staple food for most countries. Carbohydrates furnish 60-80% of the total calories intake. A minimum quantity of 5g of carbohydrate per 100 Kcal of the total diet is necessary to prevent the development of ill-effects of fasting of high fat and protein diet.

The main sources of carbohydrates are :

(1) Cereals or grains-wheat, maize,rice,oats,barley,sorghum and millets.
(2) roots and tubers-potatoes, sweet potatoes
(3) sugar, honey, beat roots, fruits and sugar-cane.