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NUTRITION & HEALTH
Food can be defined as anything edible that can be solid, semisolid or liquid
which when swallowed, digested and assimilated in the body, proves useful
to it. These substances not only keep the person alive, but also provide
energy used for growth and development, regulate the body processes and
protect the body from diseases.
NUTRITION & HEALTH
Nutrition is defined as the science of foods, nutrients and other substances
they contain; and of their actions within the body including ingestion,
digestion, absorption, metabolism and excretion.
Nutrients are organic or inorganic substances present or contained in food
which is required or necessary for growth and maintenance of function of
body.” E.g.: Proteins, Vitamins etc.
Or
Nutrients have been defined as “chemical substances found in food that cannot
be synthesized at all or in sufficient amounts in the body, and are necessary for
life, growth and tissue repair”.
Or
Nutrient “or “food factor” are organic and inorganic complexes contained in
food, which are responsible for the functions of foods and protect the body
from disorders.
Balanced Diet A balanced diet is one which includes a variety of foods in
adequate amounts and correct proportions to meet the day’s requirements of
all essential nutrients such as proteins, fats, carbohydrates, vitamins,
minerals, water, and fibre.
1. Food is a basic and foundational part of our lives. Food plays a vital role
for human existence just as the air we breathe and the water we drink.
The food we eat is utilized in the body and assimilated substances are
used for growth and maintenance of the tissue.
2. People who eat right foods rich in nutrients enjoy their lives more, live
longer, and are at a reduced risk of disease.
3. Good nutrition is critical in preventing not only deficiency diseases, but
also chronic diseases. Nutrition is vital to our bodies as water is to
plants. An unhealthy diet increases the risk of many diet related diseases.
THE RELATIONSHIP BETWEEN NUTRITION AND HEALTH
 Food can be classified in accordance to their chemical property, to their
function, to their essentiality, to their concentration and to their nutritive
value. A classification based on nutrients present will ensure that all nutrients
are made available to the body and offer greater variety within the group.
 There are five basic food groups suggested by the Indian Council of Medical
Research (ICMR). These include:
 Cereals, grains and products
 Pulses and legumes
 Milk and meat products
 Fruits and vegetables
 Fats and sugars
CLASSIFICATION OF FOOD
Cereals, grains and products
Pulses and legumes
Milk and meat products Fruits and vegetables
Fats and sugars
a) According to the chemical nature
i. Carbohydrates
ii. Vitamins
iii. Proteins
iv. Dietary Fiber
v. Fats
vi. Water Minerals
b) ACCORDING TO THEIR FUNCTION IN THE BODY
Energy giving foods:
• The carbohydrates, fats and the protein are considered as calorie nutrients, so that the body can
perform the necessary functions. Rice, chapatti, bread, potato, sugar, oil, butter and ghee are
examples of energy giving foods.
Body building foods:
• Foods such as proteins, fats and carbohydrates are also called as body-building food. They are the
nutrients that form body tissues. Fish, meat, chicken, eggs, pulses, nuts and milk are some body
building foods.
Protective foods:
• Vitamins and minerals are the nutrients that function to regulate body processes. They protect us
from various diseases. Fruits and vegetables are some examples. Therefore we must eat these
regularly.
c) According to its mass depending on the quantity necessary for cells and
organisms are classified as:
1. Macronutrients: Macronutrients are required in large quantities daily.
Proteins, carbohydrates and fats are macronutrients. They are the basis of
any diet.
2. Micronutrients: Micronutrients are needed in small quantities (usually in
amounts less than milligrams). These nutrients are involved in regulating
metabolism and energy processes. They are vitamins and minerals.
Micronutrients
Macronutrients
Water
d) According to its origin
• Depending upon the origin of food it has been classified as animal food
sources and plant food sources.
FUNCTIONS OF FOOD
NUTRIENTS
• The substances which are present in the food and consumed in our body for its
vital functions are called nutrients. According to the World Health
Organization (WHO), these nutrients must come from food, and they are vital
for disease prevention, growth, and good health. There are several constituents
such as:
 Carbohydrates are the chief sources of energy (Providing 4 Kcals/gm).
 Carbohydrates consist of carbon, hydrogen, and oxygen.
 The general empirical structure for carbohydrates is (CH2O)n. (1:2:1)
 The building blocks of all carbohydrates are simple sugars called
monosaccharide.
Classification of Carbohydrates
• Monosaccharide: these are the simplest form of carbohydrates containing
simple sugar molecule. Example: Glucose, Fructose and Galactose.
• Disaccharide: These carbohydrates composed of two units of
Monosaccharide’s. Example: Sucrose, Lactose and Maltose.
• Polysaccharide: These are the complex sugars containing numerous units of
monosaccharide molecules. Example: Glycogen, Cellulose and Pectins.
Carbohydrates
Daily requirements
Carbohydrate intake should be in the range of 300-500gm (50%- 70%) out of the total energy
intake for adults and 40-60% for children.
Sources
All sugars, Jaggery, Honey, Pulses, Whole Grains, Cereals, grains, rice, fruits, milk, yogurt,
beans, roots and tubers such as potatoes, beet root etc.
Functions of Carbohydrates
a) Living organisms use carbohydrates as accessible energy to fuel cellular
reactions.
b) They are the most abundant dietary source of energy (4kcal/gram) for all living
beings.
c) Stored carbohydrates act as an energy source instead of proteins.
d) Carbohydrates are intermediates in the biosynthesis of fats and proteins.
e) Carbohydrates aid in the regulation of nerve tissue and is the energy source for
the brain.
f) Formation of the structural framework of RNA and DNA (ribonucleic acid and
deoxyribonucleic acid).
g) They help in the modulation of the immune system.
Digestion And Absorption
of Carbohydrate
Overeating of Carbohydrate
 Proteins are the essential constituents of the diet. Proteins are made up of amino
acids. Amino acids are needed for replacement and growth of the body parts.
 Amino acids are classified as essential and non essential amino acids. Essential
amino acids cannot be synthesized by the body and must be taken through foods
whereas non essential amino acids can be synthesized by the body.
DAILY REQUIREMENTS
 The ICMR recommends 1gm of protein/ Kg of body weight for adults.
 The amount of protein should be increased for children, pregnant and lactating
mothers by 1.5- 2.0 g/kg body weight.
II. Proteins
Sources of Protein
FUNCTIONS OF PROTEINS
1) Protein helps in synthesis of enzymes, immunoglobulin, plasma proteins and hormones in
the body.
2) Protein helps in growth and repair of body tissues
3) Proteins are secondary sources of energy during deficiency of carbohydrates and fats.
(Provides 4 Kcals/gm).
4) Proteins help in forming haemoglobin.
5) Proteins help in antibody formation.
Digestion And Absorption
of Protein
Deficiency of Protein
Kwashiorkor
 Fat are concentrated sources of energy containing Carbon, hydrogen &
oxygen.
 Fat are solid up to 200
C and if they are liquid at that temperature they are
called Oils.
 Fat are insoluble in water and soluble in Chloroform, petrol and Ether.
 Fat is deposited as adipose tissue in the body and perform essential functions
in the body.
 Fats are composed of fatty acids and contain oxygen, carbon and hydrogen.
3- Fats
CLASSIFICATION
 Fats are classified in to:-
1) Simple Lipids (Ex. Triglycerides)
2) Compound lipids (Ex. Phospholipids)
3) Derived lipids (Ex. Cholesterol)
 Fats are classified in to two types: Saturated fat and unsaturated fat.
 Saturated Fat: These have full number of hydrogen atoms. These are from
animal sources. Example: Butter, Ghee and vegetable oil.
 Unsaturated Fat: These contain one, two or more double bonds of fatty
acids. These are extracted from vegetable sources. Example: Groundnut oil,
soyabean oil, sunflower oil.
DAILY REQUIREMENTS
 15-20% of total calorie requirements should be from fat. That is about 44 gm
to 77 gm. of fat per day if you eat 2,000 calories a day.
 Fats are classified in to two types: Saturated fat and unsaturated fat.
 Saturated Fat: These have full number of hydrogen atoms. These are from
animal sources. Example: Butter, Ghee and vegetable oil.
 Unsaturated Fat: These contain one, two or more double bonds of fatty
acids. These are extracted from vegetable sources. Example: Groundnut oil,
soyabean oil, sunflower oil.
DAILY REQUIREMENTS
 15-20% of total calorie requirements should be from fat. That is about 44 gm
to 77 gm. of fat per day if you eat 2,000 calories a day.
 Supplies energy (9 kcals/ gm).
 Improve the palatability of food (flavor and taste)
 Supports body organs like liver and kidneys
 Provides insulation and thermoregulation against cold
 Provides essential fatty acids which helps in growth, promotion and
maintenance of skin integrity.
 Helps in formation of hormones in the body.
 Helps in transportation of fat soluble vitamins.
FUNCTIONS
Vitamins
• Vitamins are organic compounds that people need in small
quantities. Most vitamins need to come from food because the body
either does not produce them or produces very little.
• Different vitamins play different roles in the body, and a person
requires a different amount of each vitamin to stay healthy.
FAT SOLUBLE VITAMINS
Vitamin-A
• The chemical name is Retinol.
• Found in foods of both plant and animal origin.
• Function: It is essential for eye health.
Deficiency
Deficiency Syndrome
 Decreased resistance to infection
 Dry scaly skin
 Night blindness (Inability to see in dim light)
 Bitot’s spots- Greyish, rough and raised patches on conjunctiva
 Keratomalacia- Softening of the cornea.
• Daily requirements: 0.4-1 mg Sources. Green leafy vegetables and yellow orange
fruits and vegetables like mango, papaya, pumpkins and carrots are good sources
of β-carotene.
Bitot’s spots
Keratomalacia
Vitamin-D
 Vitamin D is synthesized by sunlight.
 Vitamin D is essential for bone growth.
Daily requirements: 400 IU Sources
 Generated in the skin by action of ultra violet rays of sunlight
 Food sources are milk, butter, cheese, egg, fish and fish liver oils, and foods
which have been fortified by addition of vitamin D.
Functions
 Increases intestinal absorption of calcium and phosphates.
 Mineralization of bones.
 Vitamin D is also essential for the dental health. It prevents tooth
decay and loss, strengthen the gums and reduces risk of any oral
infection.
Rickets characterized by reduced
growth and softening of bones. This
disease is generally seen in children
due to lack of vitamin D. Children
develop very thin, deformed bones
Osteomalacia, similar to rickets but is
usually seen in elderly people suffering
from vitamin D deficiency.
This disease reduces the absorption of
calcium in the body leading to soft and
deformed bone structure, bending of the
spinal cord and legs and increased risk
of fractures.
Osteomalacia
Rickets:
Osteoporosis, being most common
in elderly where the bone density
reduces, making it more porous in
nature and causing increased risk of
broken bone and fractures.
Osteoporosis
Vitamin E
• Vitamin E is an antioxidant and formed up of chemical substance
called Tocopherols.
Daily requirements:
• 15UI per day.
Sources
• Milk, oils, eggs, leafy vegetables, papaya, grains, nuts.
Functions
• Antioxidant (Prevents the formation of oxidative free radical)
• Co factor in electron transport
• Prevents or delays the ageing.
Vitamin K
• It is called as Antihemorrhagic vitamin. It is required for the
fromation of Prothrombin in the liver the 2nd
factor of coagulation.
• Due to deficiency of Vit. K the prothrombin content in blood may lead
to bleeding disorder.
Daily requirements
• WHO suggested RDA of 55 μg per day for adults.
Sources
• Green leafy vegetables, cereals, fruits.
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