Human Nutrition - TYPES OF FOOD

Subject: Social Medicine and Community Health
Human Nutrition



Everyone’s basic drive for food to satisfy his hunger. Food has it importance into the 

physical, economic, psychological, intellectual and social life of human being. It is a part of 

his culture and is filled with many different meanings and symbolism for each and every 

person according to their physical age and maturity level. Food can be defined as any 

substance that, when taken into the body, will perform one or more of the following function: 

(i) build new tissues and maintain repair old body tissue.;(ii) Provide energy; and (iii) 

regulate body process.

Learning Outcomes:

Up on completion of this module, the reader will be able to:

 Specify the relation of food to health.

 Describe functions of food.

 Classify different kinds of food.

 Describe different food groups.

 Understand importance of food pyramid in human health.


1. Relation of food and human health

Good health plays important role in our happiness and our ability to work 

productively. It is directly related to the food consumed. To maintain good health, ingesting a 

diet containing the nutrient in a correct amount is very essential. A balance diet is one which 

contains different types of food in such quantities and proportions so that need for calories, 

protein, fats, minerals and vitamins are adequately met and a small provision is made for 

extra nutrient to withstand short duration of leanness. Deficiency of any nutrient affects the 

health of individuals. Foods not only contains nutrient but they are also rich in nutraceuticals 

which prevent degenerative disease. Consuming predominantly plant-based diets reduces the 

risk of developing obesity, diabetes, cardiovascular diseases, and some forms of cancer. 

Plant-based diets are high in vegetables and fruits, wholegrains, pulses, nuts and seeds, and 

have only modest amounts of meat and dairy. These diets help to achieve and maintain a healthy weight, reduce blood pressure, and are also rich in sources of dietary fibre (which 

protects against colorectal cancer). Fruits and vegetables independently contribute to 

preventing cardiovascular disease. It is likely that particular vegetables and fruits, including 

cruciferous vegetables such as cabbage and broccoli, and many fruits or vegetables that are 

rich in folate, also protect from developing cancers of the colon and rectum, mouth, pharynx, 

larynx and oesophagus. Eating red and processed meat increases risk of developing colorectal 

cancer. Saturated fat and trans fats increase blood cholesterol and cardiovascular risk. Higher 

sodium/salt intake is a major risk factor for elevated blood pressure and cardiovascular 

diseases, and probably stomach cancer. Diets high in meat and dairy also increase blood 

pressure. Diets high in energy-dense, highly-processed foods and refined starches and/or 

sugary beverages contribute to overweight and obesity.

2. Functions of food.

Functions of food can be classified according to their functions in the body.

2.1.Energy yielding

The first function of food is to provide energy to the body for various physiological 

processes which is essential for continuance of life to carry out professional, household and 

recreational activities. Ingested food is converted into different nutrients in the body after 

digestion , absorption and various metabolic process for growth and to keep the body warm. 

Energy needed is supplied by the oxidation of the foods consumed. One gram carbohydrate 

gives 4 kilocalorie, Protein 4 kilocalorie and Fat provides 9 kilocalories. Energy yielding 

foods can be divided into two parts :

 Cereals, pulses, nuts and oil seeds , roots and tubers.

 Pure carbohydrate like sugar, fat and oils.

2.2. Body Building Functions

Foods rich in protein are called body building foods. They are classified into two 


 Milk, Egg, Meat and Fish - They are rich in proteins which are of high biological 

value. These proteins have the essential amino acids in appropriate amount for the 

synthesis of the body tissues.

 Pulses, oil seed and nuts – They are rich in protein but may not contain all the 

essential amino acids required by the human body.

The food we eat become part of us. Thus one of the most important functions

of food is building of the body. A newly born baby weighing 2.7 kg to 3.2 kg can 

grow to it efficacious adult size of 50-60 kg if appropriate type and amount of foods 

are eaten from birth to adulthood. The food eaten each day helps to maintain the 

structure of the adult body and replace denatured cells of the body.

2.3. Protection and Regulatory functions

Foods rich in protein, vitamins and minerals have regulatory functions in the body i.e; 

Maintenance of heart beat, water balance, maintenance of body temperature etc. Protective 

foods have been classified into two groups.

 Foods rich in protein , mineral and vitamins of high biological value e.g milk , egg , 

fish , liver etc.

 Foods rich in certain vitamins and minerals only e.g green leafy vegetables and fruits.

2.4. Maintenance of Health

Foods are rich in phytochemicals and antioxidants which helps in prevention of many 

degenerative diseases. Some of the food acts as nutraceuticals which plays an important 

role in the prevention of cancers, heart disease, diabetes mellitus and various non 

communicable and communicable diseases.

2.5. Psychological Functions of Food

In addition to various biological functions, food acts as satisfying certain emotional 

needs of the humans. It includes a sense of security, love and attention. Each and 

everyone’s sentiments are the basis of the normal attachment to the mother’s cooking. 

Sharing of food among friends is a token of love and affection. 

2.6. Social Functions of Food

Food has always been a central part of our society. It reflects our community, social, 

cultural and religious life. Special foods are distributed as a benediction or Prasad in the 

religious functions in home, temples and churches. As like feasts are given at specific 

stages of life such as birth , naming ceremony, birthday and marriages. Food has been 

used as expression of love friendship and social acceptance.

3. Classification of foods

Foods may be widely classified into 11 groups based on their nutritive value. They 


3.1. Cereals And Millets

Cereal grains are seeds of the grass family. Cereals and millets form a major group of 

foodstuffs as they form staple food of a large majority of the population all over the world.

About 70-80% of the diets of the low income group in India and other developing country 

come from this group. Cereals and millets contains 6 – 12 % protein and they are very good 

source of vitamins e.g; thiamine, niacin, pantothenic acid and vitamin B6and mineral like 

phosphorus and iron. This group provide 70 – 80% of the calories, proteins and other 

nutrients in the diets of the low income groups. All the cereals except ragi are poor to 

moderate source of calcium. Ragi is one of the richest source of calcium containing about 

0.4% calcium. Cereals are deficient in vitamin A,D, C and B12 . Yellow maize however 

contains fair amount of carotene (Provitamin A). Puffed cereals are also consumed. Cereals 

are comparatively inexpensive so it forms staple diet and contribute to the most of the calorie 

and protein requirement. Cereals improve the quality of protein. Wheat, rice, oats, rye, barley 

are example of some main cereals. Maize or corn, jowar, ragi , bazaar, are some millets 

3.2. Pulses

In vegetarian diet pulses are very important source of protein. Pulses are edible fruits 

or seeds of Pod bearing plants belonging to the family of leguminous. Dried pulses contains 

20 – 25% of protein which is just double to cereal protein.. They are very good source of

many B vitamins and minerals, but are deficient in A, D, B12 and C. They supplement 

effectively cereals. Puffed pulses e.g puffed Bengal gram and peas are consumed commonly 

as a snack by the low income group in India. Pulses give 340 kilo calories per 100 gm which 

is almost similar to cereals calorie value. The qualities of protein in pulses are of low quality 

they are deficient in methionine and red gram is deficient in tryptophan also. Pulses are rich 

in lysine so they can supplement cereal protein. The most effective combination to get the 

maximum supplementary effect is one part pulse protein and five part of cereal protein.

3.3. Nuts and Oil Seeds

Nuts are seeds of fruit consisting of an edible fat containing kernel and surrounded by 

a hard or brittle shell. Nuts have rich flavour. They are rich in protein particularly the amino 

acid arginine. They contain high level of fat. Hence, they are not only good source of protein  but are concentrated source of energy. Nuts contain saturated fatty acid in very less amount 

and are rich in monounsaturated and polyunsaturated fatty acids. They can be included as 

cholesterol lowering diets. Consumption of nuts reduces total cholesterol and LDL (bad 

cholesterol) without changing the level of HDL (Good cholesterol). Besides their fatty acid 

profile they are very good source of several other important nutrients including selenium, 

potassium, iron , manganese, copper, phosphorus and zinc. 

3.4. Vegetables

Vegetables are the plants or part of the plants that are used as food. The term 

vegetable is used in a very narrow sense to those plants or part of plants that are served raw 

or cooked as a part of the main course of meal. Besides providing variety to the diet they 

supply many nutrients. They make food attractive by their colour , texture and flavour. 

Vegetables are classified according to the part of the plant consumed or colour of the 

vegetable or according to their nutritive value. Vegetables are called protective foods because 

of their minerals and vitamin contents. Nutritionally they are classified into three groups;

 Green leafy vegetables

 Root and tubers

 Other vegetables

The expert committee of the Indian council of the Medical Research (ICMR) has 

recommended that every individual should consume at least 300gm of vegetables 

(GLV – 50 gm, Other vegetables – 200 gm and Root and tubers 50 gm ) in a day.

 Green Leafy Vegetables

Leaves are the manufacturing part of the plant where the life giving pocess of 

photosynthesis takes place. Green leafy vegetables are very low in carbohydrate and 

energy but they are good source of ß carotene, calcium, riboflavin, folic acid, ascorbic 

acid, iron and vitamin K. Among all green leafy vegetables colocasia leaves contains 

highest quantity of ß carotene and cabbage is the poor source of ß carotene. GLV also 

contains vitamin C and it can be used as a substitute of fruits e.g; Agathi, drumstick 

leaves, and coriander.

 Root and Tubers

The important foods in this group are potato, sweet potato, tapioca (cassava) 

carrot, elephant yam and colocasia. They are good source of carbohydrate and provide 

more calories. Carrots are good source of carotene in this group. Roots and tubers are 

fairly good source of vitamin C. They are poor source of protein, calcium, iron and 

Vitamin B.

 Other Vegetables

This group contains large number of vegetables. Some of them are good 

source of vitamin C. Yellow pumpkin is a fair source of carotene. Vegetables of this 

group contain high moisture so they are highly perishable. They contribute fibre 

content to the diet. 

3.5. Fruits

Fruits are produced from flowers and they are ripened ovary or ovaries of a 

plant together with adjacent tissue. Fruits are fleshy or pulpy in character often juicy and 

usually sweet with fragrant, aromatic flavours. Fruits are poor source of protein, calorie and 

fat. Avacado is exception containing 28 percent fat. Alpha linolenic acid is present in plum, 

papaya and guava. Fruits contain n-3 fatty acids. Generally they are poor source of iron 

except seethaphal. Mango, Indian dates and papaya are good source of ß carotene. Guava 

and citrus fruits are good source of vitamin C. Fruits contains 75 to 90percent water.

Phenolic compounds present in berries nd grapes protect against oxidative damage of tissue 

and inflammation. Fruits can be classified into various group according to their shape, cell 

structure and type of seed:

 Berries – Strawberries, gooseberries, blackberries, raspberries, blueberries.

 Citrus Fruit – Sweet lime, orange, tangerines,sour orange, lime, lemon grape fruit.

 Drupes – Apricot, sweet cherry, peach, plums.

 Grapes – Green grapes , black grapes, seedless grapes.

 Melons – Musk melons, water melons.

 Pomes – Apple, Pears.

 Tropical and subtropical fruits – Guava, avocado, banana, dates, Amla, jackfruit, 

mango, jambu fruit, papaya, passion fruit, pine apple pomegranate, sapota, 


3.6. Milk and Milk Products

Nature has provided milk as one of the best food which has no adequate substitute. 

Milk is a complex mixture of lipid, carbohydrate, proteins and many other mixtures of 

organic compounds and inorganic salt dissolved or dispersed in water. Milk is a complete 

food except deficient in iron and vitamin C. Milk has high biological value. It contributes to 

the nutritive value to the diet in form of milk shakes, plain milk, flavoured milk, curd, 

cheese, butter mlk etc.

3.7. Eggs

Egg is widely used by humans. Although egg of all birds may be eaten but hen egg is 

more often than any other. Hen’s egg contains about 13% protein of very high biological 

value and 13% fat. It is a rich source of vitamin A and some vitamin B. Egg are used as 

boiled, scrambled or poached. 

3.8. Meat, Fish and other animal food


The term meat refers to the muscles of the warm blooded animals mainly cattle, 

sheep, pig, etc. Meats also include the gland and organs of these animals. Meat product 

include many of the products from animal slaughter such as animal gut used for sausage 

casing, the fat in the manufacture of lard, gelatine and others. Meat is rich in protein (18 – 22 

%) of high biological value. Out of total nitrogen content of meat 95 % is protein and 5% is 

the smaller peptides and amino acids. The amino acid of made from meat protein is very 

good for maintenance and growth of human tissue. Biological value of meat is better than 

vegetables. Fat content of meat varies from 5 to 40% with the type, breed and age of the 

animal. Meat fats are rich in saturated fatty acids. Carbohydrate is found in the form of 

glycogen and glucose in very small quantity. It is fair source of vitamin B. It is nil in vitamin 

A, C and D.


Fishes are excellent source of protein due to its quality and quantity. They contain 

around 20% protein. The biological value of fish is 80. Fish is rich in lysine and methionine 

so it has supplementary value with cereals and pulses. Fish contains saturated fatty acid 

(40%) monounsaturated fatty acid (25%) , polyunsaturated fatty acids (n-3 25%, n-6 10%). 

Fresh water fish contains eicosapentaenoic acid and decosahexaenoic acid which are 

polyunsaturated fatty acid. Fishes are rich in phosphorus, but are deficient in calcium. Small 

fish eaten with bone are good source of calcium.


Liver is rich in protein (18- 22%) , vitamin A and B complex. It is the richest natural 

sources of calcium.

3.9. Fats and Oils

Fats and oils are good source of energy and provide essential fatty acids. Butter and 

ghee and vanaspathi are good source of vitamin A. Fat is present naturally in foods. Besides 

their nutritional function oils and fats have their uses in cookery which are derived principally 

from their distinct physical property. Fat plays an important role in the proper development of 

texture of the foods e.g cakes, biscuits and cookies. 

3.10.Sugar and other

The carbohydrate foods commonly used are cane sugar, jaggary, glucose, honey, 

syrup, custard powder, arrowroot flour and sago. They serve mainly as source of energy. 

Honey and jaggary contains small quantities of mineral and vitamins.

3.11. Spices, Herbs and Condinments

Aromatic food substances which enhance flavour are spices and herbs. Spices are 

generally died roots, barks or seeds which are used whole, crushed or in powdered form. 

Herbs are usually fresh leaves, stems or flower of herbaceous plants. Spices add flavour to 

the food and make the food palatable and hence add variety to the diet. It stimulates

salivation, acid secretion and digestive enzymes. Some spices have anti inflammatory, antibacterial, and anti oxidant properties. It helps in improving impaired blood glucose and 

reduces cholesterol levels. 

3.12. Beverages

A beverage is composed mainly of water and it is used as drink to get relief from 

thirst and maintain fluid in the body. It includes many liquid or liquorous foods, such as 

coffee, tea, cocoa, soft drinks and alcohol containing drinks. It nourishes the body as well as 

maintains body fluid level. Beverages can be classified according to their functions.

 Refreshing: Plain water, carbonated beverages not containing fruit juices, fruit juics, 

iced tea, butter milk with salt and lime juice.

 Nourishing: pasteurised milk, skimmed milk, malted milk, butter milk, chocolate 

and cocoa; milk shakes; egg nogs made with whisky , rum ,brandy, fruit juices, 

coffee and chocolate; fruit juice; glucose and lemonade.

 Stimulating: Egg nogs made with whisky, rum, brandy, coffee; coffee or tea and 

cocoa or chocolate beverages.

 Soothing: warm milk or hot tea.

 Appetising: Soups, fruit juices and alcoholic drinks in limited quantity.

Particular beverages may act as more than one function.

4. Food Groups.

The nutrition expert group of Indian Council of Medical Research, India has suggested five 

food group plan. US department of agriculture has suggested three different groups (i) The 

Seven food group plan, (ii) The four food group plan. (iii) The 11 food group plan for 

planning balanced diet. According to nutritional point of view foods are foods are divided in 

nine groups.

4.1. Five food group plan (Nutrition expert group I.C.M.R)

Food Group Nutrient contributed

1. Milk group

This include other protein rich foods 

such as , pulses, nuts , egg, meat fish etc

Rich source of protein, mineral and vitamins.

2. Fruits and green leafy vegetables

Papaya, orange, mango Indian goose 

berry, guava, etc and all green leafy 


Rich source of certain vitamin and minerals

3. Other Vegetables

Beans, brinjal, ladies finger etc Fair source of certain vitamins , minerals and 


4. Cereals, roots and Tubers

Rice, wheat, maize, ragi, pearl millets, 

etc, and potato, tapioca, sweet potato 


Rich source of starch- fair to good source of 

protein and certain Vitamin B

5. Fats and oils and pure Carbohydrate 


Vegetable oils, animal fats, sugar, 

jiggery, honey, sago, custard powder 

starch etc.

Rich source of energy. Vegetable oils are fair 

source of essential fatty acids (EFA) and 

vitamin E.

Butter is a good source of Vitamin A. Animal 

fats are good source of cholesterol but poor 

source of EFA and vitamin E

Pure carbohydrate foods are rich source of 


4.2. The Basic 7 – Food Groups ( U. S department of Agriculture)

The 7 food group plan was developed by u.S department of Agriculture in 1943.

The 7- Food Group Main nutrient contributed

1. Green and yellow vegetable Carotene (Provitamin A), Ascorbic acid and 


2. Oranges, grape fruits, tomatoes, or 

raw cabbages or green salad

Ascorbic acid

3. Potatoes, other vegetables and fruits Vitamin minerals in general and Fibre.

4. Milk and Milk products Protein , vitamins, calcium and phosphorus

5. Meat, poultry, fish and eggs Protein, phosphorus, iron and B-Vitamins

6. Bread, Flour and cereal (whole grain, 

enriched or restored)

Thiamine, Niacin, Riboflavin, Iron, 

Carbohydrate and Fibre

7. Butter of fortified and margarine Vitamin A and Fat

4.3.The Four Food Group Plan

The four food group plan was developed by U.S Department of Agriculture in 1956.

The 4- Food groups Main Nutrient Contributed

1. Milk Group

Milk cheese, ice cream, Protein, Calcium , Phosphorus And Vitamin

2. Meat group

Beef, lamb, veal, pork, poultry fish and 


Protein , phosphorus, iron and B- vitamins

3. Vegetable- fruit group Vitamin, Mineral and Fibre

4. Bread Cereal groups ( whole grain, 

enriched, restored)

Thiamine, Niacin, Riboflavin, Iron 

Carbohydrate and fibre

4.4. The 11 Food Groups

The four food group plan was suggested by U.S Department of Agriculture in 1964.

Food Groups Main Nutrient Contributed

1. (a). Milk and Cheese Protein, calcium, Phosphorus and vitamins

(b). Ice cream Fat and Carbohydrates

2. Meat , Poultry and Fish Protein, phosphorus, iron and B-vitamins

3. Eggs Protein, Fat Vitamin, Iron and Phosphorus

4. Dry beans, Peas and Nuts Protein and B-Vitamins

5. Flour, Cereals, and baked products Thiamine, Niacin, Riboflavin, Iron 

Carbohydrate and fibre

6. Citrus Fruits and tomatoes Ascorbic acid and potassium

7. Dark green and deep yellow 


Provitamin A(carotene), ascorbic acid and 


8. Potatoes Carbohydrates and ascorbic acid

9. Other Vegetables and fruits Ascorbic acid and fibre

10. Fats and Oils Essential fatty acids and Vitamin E

11. Sugar, syrup and preserves Carbohydrates

5. Food pyramid and its importance for human health

A food pyramid or diet pyramid is a pyramid-shaped diagram representing the optimal 

number of servings to be eaten each day from each of the basic food groups. The first food 

pyramid was published in Sweden in 1974. The food pyramid introduced by the United States 

Department of Agriculture in the year 1992 was called the "Food Guide Pyramid". It was 

updated in 2005 and then replaced by “My Plate” in 2011. In 2005, the USDA updated its 

guide with My Pyramid, which replaced the hierarchical levels of the Food Guide Pyramid 

with colorful vertical wedges, often displayed without images of foods, creating a more 

abstract design. Stairs were added up the left side of the pyramid with an image of a climber 

to represent a push for exercise. The share of the pyramid allotted to grains now only 

narrowly edged out vegetables and milk, which were of equal proportions. Fruits were next in 

size, followed by a narrower wedge for protein and a small sliver for oils. An unmarked white 

tip represented discretionary calories for items such as candy, alcohol, or additional food from any other group. My Plate is the current nutrition guide published by the United States 

Department of Agriculture, consisting of a diagram of a plate and glass divided into five food 

groups. It replaced the USDA's My Pyramid diagram on June 2, 2011. Healthy eating habits 

and adequate physical activity are a key to a healthy life. If we eat the wrong kind of food and 

eat more than what our body requires then the person becomes over weight and gets prone to 

disease. Appropriate lifestyle can prevent diseases, improve quality of life and increase life-

expectancy. Remember, no one food can make you healthy. Eat a varied selection of foods 

from every level of the food pyramid. Each of the basic food groups supplies different 

nutrients, vitamins and minerals, giving your body the healthy nutrition needed. Eat plenty of 

fresh fruits and vegetables, eat whole grains, be physically active for 150 minutes per week, 

reduce salt in the diet, reduce refined carbohydrates, decrease saturated fats and avoid trans-

fatty acids, cut down on extra body fat and you can prevent diabetes, blood pressure, heart 

attacks, strokes, cancers, anemia. USDA nutritionists spent many years designing, testing, 

and refining the Food Guide Pyramid. The goal was to have an easy-to-use graphic that 

would help people select a diet that promoted nutritional health and decreased the risk of 

disease. They designed the Pyramid to be flexible enough to be used by most healthy 

Americans over the age of two. However, they also recognized that people with substantially 

different eating habits, such as vegetarians, may need a different food guidance system.

The Pyramid includes five major food groups, each of which provides nutrients needed for 

good health. By making healthful choices within these food groups, like selecting low-fat and 

high-fiber foods, people can promote good health and reduce their risk of disease. The 

placement of foods within the Pyramid shows that foods of plant origin should supply most 

of the servings of food in the daily diet. The Breads, Cereals, Rice, and Pasta Group forms 

the base of the Pyramid, with the largest number of servings recommended (six to eleven 

servings recommended daily). The next layer up includes the Fruit Group (two to four 

servings) and the Vegetable Group (three to five servings). At the third level are the Milk, 

Yogurt, and Cheese Group (two to three servings) and the Meat, Poultry, Fish, Dry Beans, 

Eggs, and Nuts Group (two to three servings). At the tip of the Pyramid are Fats, Oils, and 

Sweets. These foods and food ingredients should be used "sparingly" to avoid excess calories

and/or fat. It is not necessary to completely avoid foods such as salad dressing, butter, 

margarine, candy, soft drinks, and sweet desserts, but they should be consumed infrequently. The Pyramid includes symbols that represent the fats and added sugars found in foods. These 

are most concentrated at the tip of the Pyramid, but are also found in foods from the five 

major food groups.

6. Points to remember:

 Choose a variety of foods in amounts appropriate for age, gender, physiological status 

and physical activity.

 Use a combination of whole grains, grams and greens. Include jiggery or sugar and 

cooking oils to bridge the calorie or energy gap.

 Prefer fresh, locally available vegetables and fruits in plenty.

 Include in the diets, foods of animal origin such as milk, eggs and meat, particularly 

for pregnant and lactating women and children.

 Adults should choose low-fat, protein-rich foods such as lean meat, fish, pulses and 

low-fat milk.

 Develop healthy eating habits and exercise regularly and move as much as you can to 

avoid sedentary lifestyle.

6. Summary

This chapter is focused on food. It includes various types of food and their function 

for human health and body. It is emphasized on food and its relation to human health. Food 

pyramid and its modification is also discussed in this chapter.

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