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Chapter: 11th 12th std standard Class Nursing Health Care Hospital Hygiene Higher secondary school College Notes

Functions of Food

Nutrients are materials present in food: They are, 1. Proteins. 2. Carbohydrates 3. Fats and oils. 4. Vitamins. 5. Minerals 6. Water.

Food and Nutrients:


Food means any substance, which can be used to the body for nourishment, that is, for its growth and maintenance. Food is necessary for life. Foods are obtained from plants of many kinds, and from birds, fish and animals.

Nutrients are materials present in food: They are,


1.     Proteins.


2.     Carbohydrates


3.     Fats and oils.


4.     Vitamins.


5.     Minerals


6.     Water.


Most food contains several of these nutrients. There is no one food in nature, which contains all nutrients. We need to know different kinds of foods, what nutrients they contain and why they are important.


Functions of Food:


For growth and development, and repairing of tissues-Protein food mainly.


To provide energy for doing work-stable foods and fats.


To help the body to function properly and to protect from diseases- vitamins and minerals.


When all these functions are fulfilled in the body, a person is in a state of good health.


Energy yielding food.


A continual need of the body is energy. Energy foodstuffs are fuel for the body to work, like diesel is the fuel for a bus to run. The harder you work, the more energy food you need. Even at rest, the body still uses energy for breathing and for the heart beating.


While burning fuel foods for energy, heat is also produced. In cold weather one can keep oneself warm by exercising and eating more energy foods.


Stable foods are cheap sources of energy. They are the basis of our diet. They contain mostly carbohydrates and also proteins in small amount. The kind of stable food we eat depends on our food habits and also what are available.


The stable food includes:


Cereals and grains: Wheat made into bread, chappati etc, rice, jowar, maize, ragi and millets.

Starchy vegetables: Potatoes, sweet potato and tapioca.


Starchy fruits: Banana, jackfruit, mango etc.


Sugar, honey and jaggery provide extra energy. They are rich in carbohydrates foods.


Fats and oils such as vanaspathi, butter, ghee, oilseeds and cooking oils are good sources of energy but they are not cheap. We should include them with each meal. Fatstores in the body are useful when more energy is needed.


Calories are the unit to measure energy. We use calories to measure how much of energy is there in certain foods. We also use calories to measure how much of energy a person needs (energy requirements).


One  gram of carbohydrate yields four calories.


One  gram of fat yields nine  calories.


One  gram of protein yields four calories.


Proteins are not included in energy yielding food because they are mainly used for bodybuilding. Here are some foodstuffs and the calories provided per 100 grams.


          Food stuff  Calories


1.       Cow milk    65

2.       Buffalo milk         117

3.       Jaggery       383

4.       Honey         320

5.       Sesame seeds        564

6.       Groundnuts          549

7.       Banana       150

8.       Tapioca      159

9.       Sweet potato        132

10. Potato   99

11. Wheat bread   238

12. Wheat flour    348

13. Chappati        124

13. Chappati        124

14.     Rice   345

15.     Ragi  331

16.     Maize          342

17. Bajra     360

Calorie requirements (energy requirements):


a)     A baby below 6 months needs 120 calories per kg of body weight per day.


b)    A baby, 7 to 12 months age needs 100 calories/kg per day.


c)     A child, 1-3 years old needs about 1200 calories per day.


d)    A child, 4-6 years old needs about 1600 calories per day.


e)     A child, 7-9 years old needs about 1800 calories per day.


f)      A child, 10-12 years old needs about 2100 calories per day.


g)     An adolescent girl 13-19 years old and boy 13-15 years old needs 2300 calorie per day.


h)    An adolescent boy 16-19 years old needs 3000 calories per day.


i)       A man with moderate work needs 2800 calories per day.


j)       A woman with moderate work needs 2200 calories per day.


k)    A woman who is pregnant needs extra 300 calories per day.


l)       A woman who is lactating needs extra 500 calories per day.


Proteins or the body-builders:


Proteins are essential for growth, for building different kinds of cells, tissues and organs of the human body. From this we can understand why pregnant women, nursing mothers, babies and children all need to have a lot of proteins in their diet.


Those who are injured or diseased need extra protein for repair of tissue. Everyone needs protein because our bodies are made up of living cells, which wear out and need replacing. For example, the life of red blood cells is only about 120 days. New red blood cells need to be synthesized constantly.

Amino Acids:


There are different types of proteins and each one is made up of different type of amino acids. There are about 20 different kinds of amino acids. When we eat a protein food, first the protein gets separated and then the protein chain is broken into amino acids.


Inside the body new proteins are synthesized by joining up the amino acids in different order according to the needs of the body. These are called body proteins.


The body can make some amino acids out of others, and these are called ' nonessential amino acids' . About 8 amino acids cannot be made by the body and must be taken in our food. They are called the ' essential amino acids' .


The protein in milk and eggs provide all these essential amino acids and these are the best bodybuilding food. Other animal proteins (meat and fish) are also good body-builders.


Vegetarians and people who cannot afford to have animal proteins can get enough essential amino acids by mixing and including more variety of plant protein food.


Many amino acids in our food are not useful for bodybuilding and so are used as fuel for energy. Those who do not get enough of the essential amino acids in their diet become malnourished. However, it is often possible to get the amino acids we need by eating two kinds of plant proteins at one time.


For example, proteins in rice are short of two essential amino acids, but pulses are rich sources of these amino acids. Therefore mixing pulses with rice makes a more nutritious diet.


In a similar way, soy flour (from soyabeans) can be mixed with wheat flour to make nutritious roti or chappaties. A mixed cereal diet is better than just one kind of cereal.


A poor family at least can cook some dark green leafy vegetables to eat with the stable food and this will help in providing some proteins.


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11th 12th std standard Class Nursing Health Care Hospital Hygiene Higher secondary school College Notes : Functions of Food |

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