COMPONENTS OF FOOD

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INTRODUCTION
COMPONENTS OF FOOD
MADE BY KARAN MALHOTRA 6C
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What is Food and what is Nutrition? Food is
any edible material that supports growth, repair
and maintenance of the body. Food also protects
the body from infections and diseases. Nutrition
is the process by which body utilizes food for
growth and maintenance and healthy living. Food
functions in the body through the nutrients it
contains
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• What are nutrients?
• Nutrients are substances found in food. These
  are
• Carbohydrate
• Fat/Oil
• Protein
• Vitamins
• Minerals
•   Since Water is indispensable for life, it is
  considered both as a food and as a nutrient.
•   Dietary Fibre and some Phytochemicals of plant
  foods, although not nutrients as such, are
  needed for good
• health.

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• What food does in the body does through the
  nutrients it contains. The body utilizes these
  nutrients to grow and keep healthy and strong.
  All nutrients needed by the body are available
  through food.
• No food by itself (except for breastmilk which
  is adequate for babies up to six months of age)
  has all the nutrients needed for full growth and
  health. Food therefore must be balanced.
• We therefore need a variety of foods to get all
  the nutrients the body needs.

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Each nutrient has its own function in the
body. Specific nutrients do their best work in
the body when present with other nutrients.
Nutrients are therefore mutually supportive.
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What are Macronutrients and Micronutrients? The
nutrients can be divided into two major groups
Macronutrients and Micronutrients.   Macronutr
ients are those that are needed in large
quantities (tens or hundreds of grams) every day.
These are Carbohydrates, protein and
fats/oils.   Micronutrients are those that are
needed in minute quantities (micrograms or at
best milligrams). These are vitamins, minerals
and trace elements.
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Carbohydrates Main function is energy production
in the body.   Largest source of energy 40 - 80
percent of the total energy intake in different
countries. Neither extreme is good. The ideal
contribution is 60 percent.   One gram of
carbohydrate provides 4 Kcal.   Grains (rice,
wheat, maize), roots and tubers (potato, sweet
potato, guam, banana) and legumes (pulses, nuts)
are rich sources of carbohydrates.
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Sweet fruits and some vegetables also provide
carbohydrate in the form of sugar.   Milk sugar
is lactose.   Honey has high content of fructose,
the sweetest of all sugars.   Soft drinks
contain sugar but almost no other nutrients.
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Carbohydrates are present in two forms   Simple
carbohydrates glucose, fructose, sugar Compound
carbohydrates starch in plants and glycogen in
animals (liver and muscles) Compound
carbohydrates are polymers of glucose.
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Carbohydrates and sugars
Digestion
in the intestine Glucose (plus other
monosaccharides) Absorbed into blood In presence
of insulin Taken up by cells In presence of
O2 Metabolized to CO2 H2O Energy (no side
effects in glucose use in the body)
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During well-fed conditions, body glucose is
stored in liver and muscles as glycogen, a
compound carbohydrate. Glycogen is therefore the
animal counterpart of plant starch.   During
starvation, glycogen of liver and muscle is
broken into glucose to provide energy.
  Glucose is the only metabolic fuel for the
brain under normal conditions.   Carbohydrates
taken in excess of energy requirements are
directly converted into fat and deposited in the
body.
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Protein  Protein is the building material for
all body parts, such as muscle, brain, blood,
skin, hair, nails, bones and body fluids. It is
essential for growth, repair of worn-out tissues,
replacement of used-up blood and resistance
against infections.   Protein comes from both
animal and plant foods. Meat, fish, egg, and milk
and milk products are rich sources of animal
protein.   Pulses, nuts and beans are rich
sources of plant protein.  Cereals are low in
protein (e.g. rice 6 8, wheat 12 14), but
because of their large quantities in the diet,
they meet a major portion of total dietary
protein requirement.
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Animal proteins are of high quality
(first-class proteins) because of their more
complete and balanced composition of amino
acids.   Plant proteins are of lower quality
(second-class proteins) because they are
incomplete in one or more of the essential amino
acids.   Combination of two or more plant foods
can mutually supplement each others deficiency
and therefore give rise to high quality protein.
For example, khichuri, which is a mixture of rice
and dal (pulse), is a good quality diet.
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The protein from beans and legumes are of better
quality than the protein from rice and wheat
products. These foods are considered less
expensive meat substitutes and are often called
the poor mans meat.   Potato is poor in
protein (lt3), but this protein is of high
quality.
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Proteins are polymers of smaller units called
amino acids, some of which can be manufactured in
the body (so-called non-essential), and others
must be provided pre-formed by food (the
essential amino acids).
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Protein Digestion in the gastro-intestinal
tract Amino acids Absorbed into blood Taken up
by the cells Synthesize body proteins
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Although the main function of protein is to build
and maintain the body, it also gives energy. One
gram of protein gives 4 Kcal.
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Fats/Oils Fats/oils are concentrated sources of
energy needed by the body. The term fat is
commonly used to refer to a family of compounds
called lipids which are water-insoluble. They
include triglycerides, phospholipids and sterols
such as cholesterol. Triglycerides predominate
both in the food and in the body. 1 gm of fat
provides 9 kcal, i.e. more than double the energy
given by carbohydrate or protein per unit weight.
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Chemically, triglycerides are fatty acid
tri-esters of glycerol   H2C O CO fatty
acid  HC O CO fatty acid  H2C O CO
fatty acid
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Fats A triglyceride may be a FAT or OIL,
depending on the predominant type of fatty acids
it contains saturated, monounsaturated and
polyunsaturated. When predominant fatty acids are
saturated and monounsaturated, then it is solid
at room temperature and is termed as FAT.
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Usually, triglycerides of land animal sources are
FATs. Examples are fats of beef, mutton, goat and
chicken skin. Saturated fatty acids are
cholesterologenic, i.e. they increase blood
cholesterol level. Aquatic animals like the fish,
especially the marine fish, have good
preponderance of polyunsaturated fatty acids and
their fat is actually OIL.
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Oils When polyunsaturated fatty acids
predominate, then it is liquid at room
temperature and is termed as OIL. Usually,
triglycerides of plant sources are
OILs. Examples are vegetable oils - mustard oil,
soybean oil, sunflower oil, corn oil and other
cooking oils. However, coconut and palm oil
contain large proportions of saturated and
monounsaturated fatty acids.
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Cholesterol Some food items are rich in preformed
cholesterol. Examples egg yolk, liver, brain,
chicken skin. Forms of blood cholesterol HDL
Good cholesterol LDL Bad cholesterol
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Fat provides the building materials for some body
parts, such as brain, nerves and hormones. It
also facilitates absorption, transport and
storage of fat-soluble vitamins A, D, E and
K. Fat is therefore an essential nutrient. Like
all other nutrients, fat is beneficial if
consumed in the right amount and if it is the
right type.
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Since high blood cholesterol is a risk factor for
coronary heart disease, diet rich in preformed
cholesterol and saturated fat is to taken with
caution after a certain age. It is, however, not
a problem for infants and young growing children.
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• Vitamins
• Vitamins are food constituents vital for life.
  They cannot be synthesized in the body and must
  therefore be taken with food. They are, however,
  needed in minute amounts.
• Vitamins help in the metabolism and utilization
  of the carbohydrate, protein and fat in the
  cells. They act as helpers (coenzymes) of
  enzymes involved in these metabolisms.
• Vitamins thus help regulate body functions and
  maintain health. They also protect the body
  against infections.

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• Vitamins are either water-soluble or
  fat-soluble.
• Water-soluble vitamins are the B-complex
  vitamins and vitamin C.
• B-complex vitamins are vitamin B1, B2, B6, B12,
  niacin, folic acid, biotin, pantothenic acid.
• Fat soluble vitamins are vitamins A, D, E and K.

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• Soluble vitamins, when taken in excess of body
  needs, are excreted in urine.
• On the other hand, fat-soluble vitamins, when
  taken in excess, are stored in the body
  (particularly liver) for use at times when the
  intake of these vitamins is inadequate.
• Most vitamins can be derived from liver,
  fruits, vegetables, legumes and grains.

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A few of the key roles and rich dietary sources
of some vitamins of public health importance are
listed in the table below.
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Vitamin D
Vitamin E
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Minerals Minerals are inorganic chemical
elements present throughout the body in varying
amounts. Like the vitamins, they cannot be
synthesized in the body and must be taken with
food. Minerals act as co-factors of enzymes for
metabolism. Minerals form part of the structure
of body tissues, such as bones, teeth and nails,
blood, nerves and muscles.
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Minerals are vital to physical and mental
development. They also help protect the body
against infections. Meat, fish, milk, cheese,
green leafy vegetables and legumes provide most
of the minerals needed by the body.
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Some of the key roles of minerals are shown in
the table below.
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• Dietary Fibre
• Dietary fibres are non-digestible,
  non-absorbable components of food.
• Fibres form the bulk of the stool and help in
  clearing the bowel and in preventing
  constipation and colon cancer.
• Fibres inhibit absorption of glucose and
  cholesterol from the GI tract, thus are helpful
  in diabetes and heart disease.
• Fruits, vegetables, pulses and whole cereals are
  sources of dietary fibre.
• Our daily diet should contain some fibre for
  good health and well being.

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• Non-nutrient components of health significance
• Some plant foods show additional health benefits
  beyond basic nutrition. These foods are called
  Functional Foods.
• These ingredients protect our body from various
  diseases like diabetes, hypertension, and some
  forms of cancer.
• Bright examples of functional foods are
  tomatoes, mushroom, apple and guava, garlic,
  onion, ginger, cloves and other spices, cabbage,
  cauliflower, broccoli, blackberry, and tea.
• The above functional foods should be a part of
  our daily dietary.