Nutrition and Diet.ppt

 One of the major functions of food is to provide
energy for various biological activities
 The daily energy intake should be sufficient to
meet the energy requirement of an individual
 The conventional unit of energy is calorie
 The thermal energy required to raise the
temperature of 1 gm of water by 1°C is known as
1 calorie (cal or small calorie)

 In human physiology, energy is generally
expressed in terms of kilocalories (Calorie,
large calorie or kcal)
 One kcal is equal to 1,000 cal
 In the international system of units, the unit of
energy has now been changed to joule (J)
 One joule is the energy required to move a
mass of one kg by one metre distance by a force
of one newton

 One calorie equals 4.184 (or roughly 4.2) joules
 Therefore,
1kcal = 4.2 kJ
1,000kcal = 4.2 MJ (megajoule)
240 kcal = 1.0 MJ
 However, kcal is still widely used as a unit of
energy

CALORIFIC VALUE OF FOODS
 The three major classes of energy-yielding
nutrients are carbohydrates, lipids and proteins
 Energy value of carbohydrates, lipids and
proteins can be measured by a bomb
calorimeter

 A weighed amount of the substance is burned in
the burning chamber of bomb calorimeter by an
electrically heated platinum wire in the presence
of oxygen
 The heat evolved is absorbed by a fixed quantity
of water which surrounds the burning chamber

 The rise in temperature of water is measured by
a thermometer
 The heat evolved by complete burning of one gm
of the substance is calculated, and is known as
its calorific value

 The calorific values of different classes of
compounds as determined by bomb calorimetry
are:
Carbohydrates : 4.1 kcal/gm
Lipids : 9.3 kcal/gm
Proteins : 5.4 kcal/gm
 However, when these compounds are oxidised
in the body, their calorific values are not the
same as measured by bomb calorimetry

 Carbohydrates and lipids liberate slightly less
energy in the body as their digestion and
absorption is not 100 percent
 A major difference is seen in case of proteins
 In a bomb calorimeter, the proteins are
completely oxidised

 In the human body, the end product of protein
catabolism is urea which still contains some
energy
 However, this energy is not available
 Therefore, the calorific value of proteins in the
body is significantly less

 The calorific values of carbohydrates, lipids and
proteins in the body are 4 kcal/gm, 9 kcal/gm and
4 kcal/gm respectively
 Alcohol (ethanol) is another energy-rich
compound, and its calorific value is 7 kcal/gm

ENERGY EXPENDITURE OF A PERSON
 The energy actually spent by a living person can
be measured by direct calorimetry or indirect
calorimetry
 In direct calorimetry,the subject is kept in an
insulated chamber surrounded by water
 The rise in temperature of water is measured
over a period of some hours and from this, the
energy produced per hour or per minute can be
calculated

 In indirect calorimetry, the energy production is
measured from the volume of oxygen consumed
and carbon dioxide eliminated by a person over a
fixed period
 The ratio of the volume of CO2 expired and O2
inspired is known as the respiratory quotient (RQ)
 The RQ of carbohydrates, lipids and proteins is
different

RQ of Carbohydrates
 RQ of carbohydrates is nearly one
 For example, complete oxidation of one molecule
of glucose requires six molecules of oxygen and
produces six molecules of carbon dioxide

C6H12O6 + 6 O2 6 CO2 + 6 H2O
RQ = 6/6 = 1

RQ of Lipids
 Lipids contain less oxygen in their molecules than
carbohydrates
 Therefore, they require more oxygen for their
oxidation
 For example, complete oxidation of one molecule
of stearic acid requires 26 molecules of oxygen,
and produces 18 molecules of carbon dioxide

C17H35COOH + 26 O2 18 CO2 + 18 H20
RQ = 18/26 = 0.7

RQ of Proteins
 Molecular formulae of proteins are quite variable
because of differences in their amino acid
compositions
 Therefore, different proteins differ in their RQ
 The average RQ of proteins is about 0.8

 On a mixed diet, the RQ is about 0.85
 At an RQ of 0.85, every litre of oxygen consumed
by an individual represents an energy production
of 4.825 kcal
 In this way, the total energy spent by an individual
over a given period can be calculated from the
volume of oxygen consumed by him and the
volume of carbon dioxide eliminated

ENERGY REQUIREMENT
 Energy requirement of an individual is equal to
his energy expenditure
 Ideally, the energy requirement should be
calculated from the energy expenditure of
individuals
 But this is not practicable

 Recommendations have to be made for a whole
community regarding energy requirement
 Factors which have to be considered while
calculating energy requirement are:
a. Basal metabolic rate (BMR)
b. Specific dynamic action (SDA) of food
c. Physical activity
d. Provision for growth

Basal Metabolic Rate
 The total energy spent or heat produced by a
subject in basal condition, i.e. complete physical
and mental rest, is known as basal metabolic rate
 BMR is expressed in kcal/hour/square metre of
body surface area

 This energy is spent for maintaining vital
physiological activities e.g. circulation,
respiration, peristalsis, maintenance of body
temperature etc
 A provision has to be made for BMR while
calculating the energy requirements

 These activities are going on even when one is at
rest or asleep
 And a certain amount of energy is required to
sustain these functions which is known as the BMR

Measurement of BMR
 The measurement is made after a 12-hour period
of rest and fasting
 The subject should be recumbent but awake
during the measurement
 The environmental temperature should be
comfortable and not above the body temperature

 BMR is usually measured by Benedict-Roth
apparatus
 The subject comfortably breathes into the
mouthpiece of the apparatus
 The oxygen consumed over a 6-minute period is
measured and corrected to NTP (normal
temperature and pressure)

 This is multiplied by 10 to get the hourly oxygen
consumption
 Assuming an RQ of 0.85, each litre of oxygen
consumed is supposed to produce 4.825 kcal of
energy
 The energy produced per hour is divided by the
body surface area of the subject to get the BMR

Body surface area of the subject can be calculated by:
1. Du Bois formula, which is:
A= H0.725 × W 0.425 × 71.84 10,000
where A is body surface area in square metres, H
is height in cm and W is weight in kg
2. Nomograms which directly relate the height and
weight of a subject with his body surface area

 The BMR is high in childhood and gradually
decreases until old age
 The average BMR of adult men is 40
kcal/hour/square metre while the average BMR
of adult women is 36 kcal/hour/square metre

 BMR can be affected by a number of
physiological and pathological conditions
 The BMR is higher in males, in young age, in
colder climate and in non-vegetarians
 BMR is increased in pregnancy, hyperthyroidism,
fevers, severe anaemia, polycythaemia etc
 It is decreased in starvation, hypothyroidism,
adrenal insufficiency etc

Specific Dynamic Action
 Consumption of food increases the energy
production in the body, even in the basal state
 This is due to SDA or thermogenic effect of food
 After consumption of food, some energy is spent
by the body for digestion, absorption, transport,
metabolism and interconversion of carbohydrates,
lipids and proteins
 The energy spent by the body to metabolise food
is known as the SDA of the food

 Proteins have the highest SDA
 When 25 gm protein is ingested, about 30 kcal
are spent in metabolising it
 The energy value of 25 gm of protein is 100 kcal
but 30 kcal have to be spent to gain this energy
 So, the net gain of energy from 25 gm of protein
will be 70 kcal only
 Thus, the SDA of proteins is about 30 percent

 SDAs of lipids is about 13 percent
 SDAs of carbohydrates about 5 percent
 When different foodstuffs are taken together, the
SDA is less than the sums of SDA of individual
foodstuffs

 Carbohydrates and lipids lower the SDA
 Lipids cause a greater lowering of SDA than
carbohydrates
 A mixed diet containing proteins, lipids and
carbohydrates has an SDA of about 10 percent

 This means that if a mixed diet having a calculated
energy value of 3,000 kcal is taken in a day, the
net energy gain would be 2,700 kcal only because
300 kcal would be spent on account of SDA to
metabolise the foodstuffs
 Therefore, an additional provision of 10 percent
has to be made for SDA while calculating the
energy requirement of a person

Physical Activity
 Physical activity involves muscular work
 This increases the energy expenditure above the
basal level
 Therefore, an extra provision has to be made for
physical activity
 The increment depends upon the type of physical
activity and its duration

 In general, physical activity can be divided into
three types depending upon one’s occupation:
1. Sedentary work
2. Moderate work
3. Heavy work

 Men, sitting at rest, spend about 100 kcal/hour
 While standing, the energy expenditure rises to
about 110 kcal/hour
 Average energy expenditure of office workers is
about 110 kcal/hour

 During moderate work, e.g. tailoring, laundering,
carpentry, wall painting, dish washing etc, the
energy expenditure is about 150 kcal/hour
 During heavy work, e.g. masonry, farming,
blacksmithy, rickshaw-pulling etc, the energy
expenditure goes upto about 280 kcal/hour
 During swimming, running, weight training etc,
the energy expenditure is still higher

 Women, sitting at rest, spend about 70 kcal/hour
 During standing, the energy expenditure goes
upto 80 kcal/hour
 During sedentary work, e.g. household work or
office work, the energy expenditure is about 90
kcal/hour

 During moderate work, the energy expenditure of
women is about 125 kcal/hour
 During heavy work, it is about 210 kcal/hour

Provision for Growth
 During infancy and childhood, an extra provision
has to be made for growth i.e. for formation of
tissues
 An extra provision has also to be made in
pregnancy to meet the requirements of the
growing foetus
 During lactation, an extra allowance is to be made
which should be equivalent to the energy value of
milk secreted by the nursing mother

RECOMMENDED ENERGY INTAKE
 The daily energy requirement of an individual can
be calculated from his/her BMR, SDA, physical
activity pattern, the hours spent in sleep, at rest
and in occupational work, and growth
requirements, if any
 The requirements differ from country to country

 Indian requirements have been recommended by
Indian Council of Medical Research (ICMR)
 These requirements are for a reference man or
woman of the community
 Necessary adjustments are made for any
deviation from the reference standard

 An Indian reference man is between 20 and 39
years of age and has a body weight of 60 kg
 He sleeps for eight hours daily
 He spends eight hours a day in light occupational
work
 He spends six hours a day sitting at rest, reading,
writing etc., and two hours a day doing household
work, walking, recreational exercise etc

 We can now calculate the energy requirement of:
• Reference man
• A moderately active man
• A very active man

Calculation of energy requirement of men engaged in
sedentary work
Activity Hours Kcal/hr Kcal (total)
Sleep 8 65 520
Sitting 6 100 600
Standing 2 110 220
Occupational work 8 110 880
Total 2220
SDA (10%) 222
Grand total 2442
Rounded off 2400

moderate work
Sleep 8 65 520
Sitting 6 100 600
Standing 2 110 220
Total 2540
SDA (10%) 254
Grand total 2794
Rounded off 2800

heavy work
Sleep 8 65 520
Sitting 6 100 600
Standing 2 110 220
Total 3580
SDA (10%) 358
Grand total 3938
Rounded off 3900

 Similarly, we can calculate the daily energy
requirement of :
• A reference woman
• A moderately active woman
• A very active woman

 An Indian reference woman is between 20 and 39
years, and weighs 50 kg
 She spends eights hours in bed and eight hours in
household work or light occupational work
 She spends six hours a day sitting at rest, reading,
writing etc and two hours a day in walking, light
recreational exercise etc

Calculation of energy requirement of women engaged
in sedentary work
Sleep 8 55 440
Sitting 6 70 420
Standing 2 80 160
Total 1740
SDA (10%) 174
Grand total 1914
Rounded off 1900

in moderate work
Sleep 8 65 520
Sitting 6 100 600
Standing 2 110 220
Total 2020
SDA (10%) 202
Grand total 2222
Rounded off 2200

in heavy work
Sleep 8 65 520
Sitting 6 100 600
Standing 2 110 220
Total 2700
SDA (10%) 270
Grand total 2970
Rounded off 3000

 Based on such calculations, ICMR (1980) has
recommended energy allowances (safe energy
intake) for Indian males and females of different
age groups

Recommended energy allowance, kcal/day (ICMR, 1980)
Infants (0-6 months) 120/ kg of body weight
Infants (7-12 months) 100/ kg of body weight
Children (1-3 years) 1200
Boys (13-15 years) 2500
Girls (13-15 years) 2300
Boys (16-19 years) 3000
Girls (16-19 years) 2200
Men (sedentary work) 2400
Women (sedentary work) 1900
Men (moderate work) 2800
Women (moderate work) 2200
Men (heavy work) 3900
Women (heavy work) 3000
Pregnancy + 300
Lactation (first 6 months) + 500
Lactation (second 6 months) + 400

DIET
 The energy requirements discussed earlier are
provided by food
 The foodstuffs consumed daily constitute diet
 However, provision of energy is not the sole
function of diet
 The diet must meet all the metabolic
requirements of an individual

 The essential components of diet are:
i. Proteins
ii. Lipids
iii. Carbohydrates
iv. Vitamins
v. Minerals
vi. Water

 Proteins, lipids and carbohydrates constitute the
proximate principles of diet, and will be
discussed here
 The roles of vitamins, minerals and water have
been discussed earlier

Proteins
 Proteins are required mainly for formation of
tissues
 Even adults require proteins for replacement of
worn out tissues
 When proteins are taken in excess, they can be
used as a source of energy also, either directly
or after their conversion into carbohydrates and
lipids

 When energy is not available in the form of
carbohydrates and lipids, tissues proteins may be
broken down and used as a source of energy
 While considering the nutritional role of proteins,
we have to take into account their quality as well
as quantity

Quality of Proteins
 All the dietary proteins are not of equal nutritional
quality
 The nutritional quality of proteins is usually
assessed on the basis of the following :
1. Essential amino acid content
2. Digestibility coefficient (DC)
3. Biological value (BV)
4. Net protein utilisation (NPU)
5. Protein efficiency ratio (PER)

Essential amino acid content
 Eight amino acids are considered to be essential
for human beings as these are not synthesised in
the human body
 These are valine, leucine, isoleucine, threonine,
methionine, lysine, phenylalanine and tryptophan

 Two amino acids, arginine and histidine, are
considered to be semi-essential because their
endogenous synthesis is not sufficient to meet
the requirements of infants and children
 The other amino acids can be synthesised in the
body in adequate quantities

 Cysteine can meet the requirement of
methionine to some extent but not
completely
 Similarly, tyrosine can partially meet the
requirement of phenylalanine

 A good protein should contain all the essential
amino acids
 Deficiency of even a single amino acid can impair
the synthesis of proteins
 Animal proteins contain all the essential amino
acids
 Vegetable proteins are usually deficient in one or
more essential amino acids

 The essential amino acid which is deficient in a
protein is known as its limiting amino acid
 Lysine and threonine are the limiting amino acids
in cereals
 Methionine is the limiting amino acid in pulses

 Groundnut is poor in lysine, threonine and
methionine
 Maize is poor in lysine, methionine and
tryptophan
 Soyabean is somewhat deficient in methionine
 Thus, animal proteins are superior to vegetable
proteins in terms of essential amino acid content

Digestibility coefficient (DC)
 This is the percentage of ingested protein
absorbed into the blood stream after digestion in
the gastrointestinal tract

Biological value (BV)
 This is the percentage of ingested protein (or
nitrogen) retained in the body after digestion
and absorption

Net protein utilisation (NPU)
 This is a measure of utilisation of dietary proteins
for protein synthesis in the body
 It depends upon digestibility coefficient and
biological value

Protein efficiency ratio (PER)
This is the gain in body weight (gm) per gm of
protein ingested

Protein content, digestibility coefficient (DC), biological value (BV), net
protein utilisation (NPU) and protein efficiency ratio (PER) of some
protein-rich foods
Protein DC BV NPU PER
content (%) (%) (%) (%)
(%)
Egg (hen’s) 13.3 98 98 96 3.8
Milk (cow’s) 3.5 95 85 81 2.0
Meat 20 96 82 79 2.8
Fish 22 96 80 77 1.7
Wheat 12 85 60 51 1.3
Rice 7 93 70 65 1.7
Maize 11 85 50 43 1.0
Bengal gram 23 84 62 52 1.1
Black gram 24 82 55 45 1.0
Green gram 24 85 58 49 0.8
Red gram 22 83 56 46 0.8
Groundnut 27 92 54 50 1.7
Soya bean 40 86 64 55 0.9

 Thus, the major animal sources of proteins (egg,
milk, meat and fish) are superior to vegetable
sources (cereals, pulses, nuts and beans) in terms
of digestibility, absorption and utilisation in the
body
 Therefore, animal proteins are considered to be
first class proteins or proteins of high biological
value while vegetable proteins are described as
second class proteins or proteins of low biological
value

 It is recommended that at least half of the protein
requirement should be met from animal proteins
 However, animal foods are beyond the reach of
large sections of population in developing
countries
 For example, per capita consumption of animal
proteins in India is 6 gm/day while it is 60 to 65
gm/day in developed countries

 Since it is not always possible to increase the
consumption of animal proteins, measures
should be taken to improve the quality of
vegetable proteins
 The drawback of vegetable proteins is the
absence or deficiency of one or more essential
amino acids

 Amino acid content of vegetable foods may be
improved by two methods
1. Mutual supplementation
2. Fortification with amino acids

Mutual supplementation
 An essential amino acid deficient in one vegetable
food may be present in another vegetable food
 If these two foods are taken together, all the
essential amino acids can be obtained
 This is known as mutual supplementation

Some useful combinations are:
1 Wheat + groundnuts
2. Wheat + pulses
3. Rice + pulses
4. Rice + groundnuts
5. Wheat + soyabean
6. Bengal gram + sesame
7. Cereals + legumes + leafy vegetables

Fortification with amino acids
 The limiting amino acid can be added to a food
e.g. wheat flour can be fortified with lysine
 The limiting amino acids in most of the vegetable
proteins are lysine, methionine, threonine and
tryptophan

 Lysine and methionine are being manufactured
on commercial scale at economic prices, and can
be used for fortification of vegetable foods
 It has been shown that fortification of vegetable
foods with their limiting amino acids leads to a
significant improvement in their protein efficiency
ratio

Protein efficiency ratio (PER) of some common
vegetable foods before and after fortification with
limiting amino acids
Food PER
Wheat 1.3
Wheat + lysine 2.4
Rice 1.7
Rice + lysine + threonine 2.0
Maize 1.0
Maize + lysine + methionine + tryptophan 2.2
Soya bean 0.9
Soya bean + methionine 3.2
Groundnut 1.7
Groundnut + lysine + threonine + methionine + tryptophan 2.9

Protein Requirement
 Protein requirement is more in growing age than
in adults
 Protein requirement is also increased in
pregnancy and lactation
 ICMR has recommended the protein
requirements of Indian subjects on the basis of
body weight

Recommended daily allowance (RDA) for proteins
(ICMR, 1981)
Daily protein intake
gm/kg of total
body weight (gm)
0-3 months 2.3
4-9 months 1.8
10-12 months 1.5
1-3 years 1.8 22
4-6 years 1.6 29
7-9 years 1.35 36
10-12 years (boys) 1.24 43
13-15 years (boys) 1.10 52
16-18 years (boys) 0.94 53
Adult men (60 kg) 1.0 60
10-12 years (girls) 1.17 43
13-15 years (girls) 0.95 43
16-18 years (girls) 0.88 44
Adult women (50 kg) 1.0 50

Lipids
 Lipids are commonly known as fats and oils
 Fats are solid at room temperature while oils are
liquid at room temperature
 Fats and oils are really triglycerides
 These are the major lipids present in food

 Smaller amounts of other lipids, e.g.
phospholipids, glycolipids, cholesterol etc., may
also be present in foods
 Except for polyunsaturated fatty acids (PUFA),
all the lipids can be synthesised in the body
 For this reason, PUFA are also known as
essential fatty acids (EFA)
 Thus, one major role of dietary lipids is to
provide essential fatty acids

 Some other functions are as follows:
1. They act as carriers of fat-soluble vitamins
2. They are a concentrated source of energy,
and spare proteins from being used as
source of energy
3. They make the food palatable
 Therefore, a certain amount of lipids must be
present in the diet

 The quantity and chemical nature of dietary lipids
should be such that our requirement of essential
fatty acids can be met but atherosclerosis is not
promoted
 Excessive intake of triglycerides, cholesterol and
saturated fatty acids promotes atherosclerosis by
raising the concentration of cholesterol in serum
 PUFA have an opposite effect

 Therefore, the lipid content and composition of
diet should be determined keeping the following
points in mind:
1. The total lipid intake should be just enough
to meet the requirements
2. Cholesterol intake should be cut down to
the minimum, preferably below 300
mg/day
3. PUFA should replace saturated fatty acids
to the extent possible

 ICMR (1981) has recommended that lipid
intake should be such that it provides 20 %
of the total energy requirement
 The essential fatty acids should provide at
least
3% of the total energy in adults, and 5-6% in
infants, children, and pregnant and
lactating women

 Lipids may be present in food as visible fat or
invisible fat
 Vegetable oils, hydrogenated vegetable oils,
butter, ghee etc, which are pure lipids, are known
as visible fat
 The lipids present in milk, meat, fish, cereals,
pulses, vegetables etc constitute invisible fat
 According to ICMR (1981), half of the total lipid
intake should be in the form of invisible fat

Lipid content (%) of some common foods
Food Lipid Food Lipid
Egg (hen’s) 11 Wheat 1.0
Fish 10 Rice 0.5
Meat 3.3 Maize 3.5
Milk (cow’s) 3.8 Pulses 5
Milk (buffalo’s) 7.5 Groundnut 40
Cheese 31 Soya bean 20
Animal foods are richer in saturated fatty acids
while vegetable foods are richer in PUFA

Fatty acid content (%)of common oils and fats
Oil or fat Saturated Monoun- Polyun-
fatty acids saturated saturated
fatty acids fatty acids
Coconut oil 92 6 2
Palm oil 46 44 10
Groundnut oil 20 50 30
Cottonseed oil 25 25 50
Soya bean oil 15 25 60
Corn oil 8 27 65
Sunflower oil 8 27 65
Safflower oil 10 15 75
Butter 60 37 3

 The PUFA essential for human beings are linoleic
acid, a-linolenic acid and arachidonic acid
 Most of the PUFA present in oils and fats is
linoleic acid
 Among vegetable oils, the only good source of a-
linolenic acid is soya bean oil

 a-Linolenic acid is also present in green leafy
vegetables
 The requirement for a-linolenic acid is very
small
 Arachidonic acid requirement is even smaller
which is easily obtained from invisible fat

 Hydrogenated vegetable oils have become a
popular cooking medium in poor strata because
of their better keeping quality
 During hydrogenation, unsaturated fatty acids
are converted into saturated fatty acids
 Thus, the EFA content is decreased
 The cis double bonds may also be converted into
trans double bonds

 The cholesterol content of food is also important
 Cholesterol is present only in animal foods

Cholesterol content (mg/100 gm) of some
common foods
Food Cholesterol Food Cholesterol
Egg 550 Milk, whole 11
Liver 300 Skimmed milk 5
Meat 65 Butter 250
Fish 70 Cheese 100

Carbohydrates
 No carbohydrate is really essential for human
beings as all the carbohydrates can be
synthesised in the human body
 However, carbohydrates form a major
component of diet because they are a relatively
cheap source of energy
 Carbohydrates are present in food generally in
three forms – starch, sugars and roughage

Starch
 Starch is the most abundant carbohydrate in food
 It is present in cereals, pulses, roots, tubers etc

Sugars
 These include monosaccharides, e.g. glucose,
fructose and galactose, and disaccharides, e.g.
sucrose, maltose and lactose
 Lactose is present in milk only
 Other sugars are present in fruits, vegetables,
honey etc

 Sucrose or cane sugar is commonly used as a
sweetening agent
 Jaggery is also used as a sweetening agent
 Besides sucrose, jaggery provides iron also

Roughage
 Cellulose is present in most vegetable foods in
varying proportions
 It can not be digested by human beings, and
constitutes roughage or fibre in the diet
 Some other polysachharides, e.g. hemicellulose,
pectin, lignin, inulin etc also contribute to
roughage

 Presence of roughage in diet is also essential as
it stimulates peristalsis and prevents constipation
 A high fibre intake has been reported to decrease
the incidence of colorectal cancer, hypertension,
diabetes mellitus etc

 No quantitative requirement can be laid down for
carbohydrates
 After calculating the total energy requirement of
an individual and deducting the contribution of
proteins and lipids, the remainder energ
requirement should be met from carbohydrates

Carbohydrate content (%) of some common foods
Food Carbohydrate Food Carbohydrate
Wheat 72 Sweet potato 34
Rice 78 Carrot 9
Maize 66 Radish 4
Sorghum 73 Peas 18
Pearl millet 67 Apple 11
Bengal gram 60 Banana 23
Black gram 60 Grape 15
Green gram 60 Guava 11
Red gram 56 Mango 18
Groundnut 22 Orange 11
Soya bean 21 Milk, cow’s 4
Onion 10 Milk, buffalo’s 4.8
Potato 20 Cane sugar 100

 Carbohydrates also have a protein sparing effect
 An adequate intake of carbohydrates spares the
proteins for tissue formation rather than being
used as a source of energy

Balanced diet
 The daily food intake (diet) should be such that
the daily requirements of all the essential
nutrients are met
 There should be neither a deficiency nor an
excess of any nutrient in the diet
 These objectives can be achieved from a
balanced diet

 A balanced diet is defined as a diet which
contains a variety of foods in such quantities
and proportions that the requirements for
energy, proteins, lipids, carbohydrates, vitamins,
essential minerals and other nutrients are
adequately met, and a small provision is also
made for extra nutrients to tide over short
durations of lean intake

 The major food groups in a usual diet are:
1. Cereals
2. Pulses
3. Vegetables and fruits
4. Milk
5. Fats and oils
6. Sugar
 In addition to these, a non-vegetarian diet
contains egg, meat and fish

 Each of these food groups has a specific
nutritional profile
 Some of these are rich in carbohydrates, some
are rich in proteins and some are rich in vitamins
and minerals

 The daily diet should contain each of these food
groups in such a combination that our daily
requirements of energy and all the essential
nutrients are met
 Before planning a diet, we should know the
nutritional profile of these food groups

Cereals
 Cereals are the largest component of an average
diet
 The major cereals are rice, wheat and maize
 Millets, which are smaller grains, are also
included in this group
 The important millets are sorghum and pearl
millet

 The cereals are a major source of energy
 Their energy content is about 350 kcal/100 gm
 The major nutrient in cereals is carbohydrate
which is present in the form of starch
 It makes up 70 - 80% of the weight of cereals

 The protein content of rice is about 7% while
other cereals contain 10 -12 % protein
 The proteins present in cereals are deficient in
lysine
 Some are deficient in threonine also

 Maize is, in addition, deficient in tryptophan
 The fat content is less than 2% in rice, wheat
and sorghum, and less than 5% in maize and
pearl millet

 The cereals contain significant amounts of
minerals but absorption of calcium, phosphorus
and iron, present in cereals, is not very efficient
 Several members of B-complex group of vitamins
are present in cereals, mainly in the outer layer of
the grain
 The removal of outer layer leads to a significant
loss of vitamins, and some loss of proteins as well

 Energy content of pulses is about 350 kcal/100
gm
 Carbohydrate content is 60-65%, fat content
less than 5% and protein content 22-24%
 Pulses are a major source of proteins for
vegetarians

 The proteins present in pulses are deficient in
methionine, but pulses and cereals supplement
the limiting amino acids of each other
 Minerals and some members of B-complex group
of vitamins, e.g. thiamin, riboflavin, niacin etc, are
also present in pulses
 Germinating pulses contain vitamin C also,
and contain higher concentrations of B-complex
vitamins

Vegetables and Fruits
 Vegetables and fruits are known as protective
foods as they are rich in vitamins and minerals
 They also provide roughage
 Some vegetables and fruits contain significant
amounts of carbohydrates also

The vegetables are generally divided into three
groups:
(a) Roots and tubers
(b) Green leafy vegetables
(c) Other vegetables

Roots and tubers
 This group includes potato, sweet potato,
colocasia, onion, carrot, radish etc
 Potato and sweet potato are fair sources of
carbohydrates
 Carrot is rich in carotenes
 Potato contains some vitamin C also

Green leafy vegetables
 These include spinach, coriander leaves,
fenugreek (methi) leaves, mint, cabbage etc
 They are good sources of carotenes, vitamins of
B-complex group, vitamin C, calcium, iron and
other trace elements
 They also add roughage to the diet

Other vegetables
 Vegetables other than green leafy vegetables,
and roots and tubers are included in this group
e.g. cauliflower, brinjal, tomato, lady’s finger,
cucumber, pumpkin, bitter gourd etc
 These are rich in vitamins and minerals
 They also add roughage to diet

 Fruits should also be considered along with
vegetables as they are excellent sources of
vitamins and minerals
 An added advantage of fruits is that they are
generally eaten raw and, therefore, the heat-
labile vitamins present in them are not destroyed
 Some fruits and/or raw vegetables (salads), e.g.
tomato, cucumber, carrot, radish etc, must be
included in the daily diet.

Milk
 Milk can form a
nearly balanced diet by
itself
 It contains all the essential
nutrients except iron
and vitamin C
 Proteins of milk contain all
the essential amino acids

 Lactose, the carbohydrate present in milk, is
particularly useful for infants and children as it
provides galactose for the formation of nervous
tissue
 Infants should be fed mother’s milk as long as
possible as it provides antibodies against many
infectious diseases
 Milk fat is rich in saturated fatty acids

Fats and Oils
 These are pure lipids
 A certain amount of fats and oils has to be used
during cooking to improve the taste of food but
excess should be avoided
 Vegetable oils should be preferred as they
provide essential fatty acids

Sugar
 Cane sugar is used as sweetening
agent
 It is pure sucrose, and provides
nothing except energy
 Jaggery provides some iron also

Egg
 Egg is an excellent food as it contains all the
essential nutrients except carbohydrates and
vitamin C
 Egg proteins are considered to be the best out
of all the dietary proteins
 Raw egg contains avidin which forms a
complex with biotin and prevents its
intestinal absorption

 Avidin is heat-labile, and is inactivated during
cooking
 Cooking also coagulates albumin and globulin,
and makes them easily digestible
 Egg yolk is rich in cholesterol and saturated
fatty acids, and should avoided by those who are
at a high risk of developing coronary artery
disease

 Meat is another good source of high-quality
proteins
 The protein content of meat is about 20%
 It is also a good source of easily available
iron
 Iron of meat is much better absorbed than iron
present in vegetable foods

 Many other minerals and vitamins are present in
meat
 Liver is rich in many nutrients
 Fat content of meat is variable, and contains
mostly saturated fatty acids
 Organ meats are rich in nucleic acids and
purines, and should be avoided by those prone
to gout

 Fish is also a good source of proteins of high
biological value
 Protein content of fish is about 22%
 Fish is rich in vitamins A and D
 Fat present in fish contains a-linolenic acid and
some other w-3 unsaturated fatty acids
 Sea fish are good sources of iodine

 Inclusion of these food groups in appropriate
proportions in the daily diet can provide all the
essential nutrients
 Within a group, one food can be replaced by
another
 For instance, rice can be replaced by wheat and
vice versa

 One pulse can be replaced by another
 Attention should also be paid to the cost of a food
item
 A costly food item is not necessarily superior

Balanced diet for adult men (vegetarian)
Sedentary Moderate Heavy
work work work
Cereals (gm/day) 460 520 670
Pulses (gm/day) 40 50 60
Roots and tubers (gm/day) 50 60 80
Leafy vegetables (gm/day) 40 40 40
Other vegetables (gm/day) 60 70 80
Milk (ml/day) 150 200 250
Oil and fat (gm/day) 40 45 65
Sugar and jaggery (gm/day) 30 35 55

Balanced diet for adult women (vegetarian)
Sedentary Moderate Heavy
work work work
Milk (ml/day) 100 150 200

Adjustment in pregnancy
The additional allowances in pregnancy are:
1. Cereals – 35 gm
2. Pulses – 15 gm
3. Milk – 100 ml
4. Sugar and jaggery – 10 gm

Adjustments during lactation
The additional allowances in lactation are:
1. Cereals – 60 gm
2. Pulses – 30 gm
3. Milk – 100 ml
4. Sugar and jaggery – 10 gm
5. Oil and fat – 10 gm

Adjustments for non-vegetarians
 Egg, meat and fish can replace some of the
requirement for pulses
 Half of the requirement for pulses can be
replaced by one egg (or 30 gm of meat or fish)
and 5 gm of oil and fat
 The entire requirement for pulses can be replaced
by two eggs (or 50 gm of meat or fish) and 10 gm
of oil and fat

Balanced diet for children (vegetarian)
Children Children Children
(1-3 years) (4-6 years) (7-9 years)
Milk (ml/day) 300 250 250

Balanced diet for adolescents (vegetarian)
Boys Girls
(10-12 years) (10-12 years)
Cereals (gm/day) 420 380
Pulses (gm/day) 45 45
Roots and tubers (gm/day) 30 30
Leafy vegetables (gm/day) 50 50
Other vegetables (gm/day) 50 50
Milk (ml/day) 250 250
Oil and fat (gm/day) 40 35
Sugar and jaggery (gm/day) 45 45

NUTRITIONAL DISORDERS
 Diseases resulting from inadequate or excessive
intake of nutrients are known as nutritional
disorders
 Disorders resulting from deficient or excessive
intake of vitamins and minerals have been
discussed earlier
 Disorders arising from inadequate or excessive
intake of proximate principles will be discussed
here

Kwashiorkor
 Kwashiorkor occurs when the diet is severely
deficient in proteins but adequate in calories
 This usually occurs when infants are weaned
from breast milk and top feeding is started
 If the diet is poor in proteins, it fails to meet the
protein requirements of the growing child

 Growth is retarded
 There is muscle wasting
 Skin is hyperpigmented in some areas and
hypopigmented in others
 Hair is brittle and discoloured

 Lack of apolipoprotein synthesis leads to
fatty liver
 Anaemia develops due to a decrease in globin
synthesis
 There is a marked decrease in serum albumin
concentration which leads to generalised
oedema

 Oedema masks muscle wasting, and gives a
rounded appearance
 Diarrhoea is common and leads to losses of
nutrients including vitamins
 Concentrations of amino acids and urea in serum
are decreased

 Kwashiorkor can be prevented by correct feeding
practices in the post-weaning period
 A small amount of animal foods (milk, skimmed
milk, egg, meat, fish etc) or a mixture of cereals
and pulses should be included in the post-
weaning diet
 Once kwashiorkor has occurred, it can be treated
by increasing the protein intake to a level that
proteins supply 20% of the total energy

 The protein intake may be raised by addition of
skimmed milk powder to the diet
 Or a mixture containing three parts of groundnut
flour and one part of Bengal gram flour or three
parts of wheat flour and one part of cottonseed
flour may be added to the diet

Marasmus
 Marasmus results from a generalised decrease
in food intake
 There is deficiency of calories as well as proteins
in the diet
 The available proteins are used as a source of
energy rather than for tissue formation

 Growth is retarded
 There is muscle wasting
 Subcutaneous fat disappears
 The child gives a shrunken appearance

 Diarrhoea is frequently present and aggravates
the problem by increasing the loss of nutrients in
stools
 Multiple vitamin deficiencies and infections
are commonly present
 Marasmus can be treated by increasing the
energy and protein intake, by supplementing
vitamins and minerals, by correcting dehydration
and by controlling the infections

Starvation
 Starvation can occur due to scarcity of food in
famine-affected areas
 It can also occur in ship-wrecked sailors and in
travellers stranded in desert
 Sometimes, it may be due to a psychiatric
condition, anorexia nervosa
 Or it may result from voluntary fasting

 When food intake stops, the body begins to use
stored carbohydrates, lipids and proteins
 The energy reserves of an average well-fed
adult are:
• 125 gm (or 500 kcal) of glycogen
• 9,000 gm (or 81,000 kcal) of triglycerides
• 5,000 gm (or 20,000 kcal) of proteins (mainly
muscle proteins)

 Even if the starving person is lying in bed, his
basal energy expenditure would be about 1,600
kcal/day
 Thus, the carbohydrate reserves are not sufficient
for even one day
 The lipid reserves can last 50 - 60 days
 The protein reserves can last 10 -15 days

 After glycogen depletion, lipids become the major
energy source
 Some proteins are also utilised for
gluconeogenesis to provide glucose to brain,
and to form citric acid cycle intermediates to
metabolise the fatty acids

 Major metabolic readjustments would occur to
prevent unnecessary wastage of proteins
 Unnecessary enzymes are not synthesised
 These include the digestive enzymes,
glucokinase, enzymes of urea cycle, enzymes
required for fatty acid synthesis etc
 Synthesis of gluconeogenic enzymes is
increased

 When fatty acid oxidation increases and
availability of glucose is poor, the rate of
formation of ketone bodies is increased
 Ketone bodies begin to appear in urine 3-4
days after complete starvation
 The brain tissue may adapt itself to use ketone
bodies as a source of energy

 When gluconeogenesis fails to keep pace with
the requirements due to decreasing protein
reserves, severe ketosis develops, and disturbs
the acid-base balance and electrolyte balance
 Death usually occurs from acidosis and
electrolyte imbalance

 The treatment consists of resumption of feeding
 Since the synthesis of digestive enzymes is
decreased and intestinal mucosa may be
atrophied, re-feeding should begin with glucose-
water, fruit juices and skimmed milk

 Later on, bread, biscuits, potatoes and eggs may
be added to the diet
 Normal diet may be given after a few days
 Severely starved persons may require
intravenous fluids and correction of acid-base and
electrolyte imbalance

Obesity
 Obesity may be defined as accumulation of
excess fat in the body
 In some subjects, it may be due to hereditary
factors or hormonal disorders
 In majority of subjects, it is due to excessive
calorie intake
 When energy intake exceeds the energy
expenditure, the extra calories are converted into
fat, and are deposited in fat depots

 Obesity predisposes the individual to many
diseases e.g. dyspnoea on exertion,
hypertension, diabetes mellitus, coronary
artery disease, cerebral thrombosis, gall
bladder stones, arthritis of weight-bearing joints
etc
 Surgical operations and labour are more risky in
obese subjects

 Before starting the treatment of obesity, we
should ascertain whether one is obese and, if
yes, what is the degree of obesity
 One way to assess obesity is by measuring skin-
fold thickness with calipers
 Skin-fold thickness is increased in obesity

 Another method is based on standard height and
weight charts
 Height and weight charts of Life Insurance
Corporation of India are considered as standard
for Indian subjects
 If the weight of a subject exceeds the ideal body
weight by 10% or more, he/she is considered to
be obese

 A simpler alternative is the calculation of body
mass index (BMI)
BMI =
 The normal BMI is 20 -25 in males and 19 - 24
in females
 A BMI above the upper limit of normal signifies
obesity
Weight in kg
[Height in metres]2

 The basic principle of treatment is to decrease
energy intake and to increase energy expenditure
 Energy expenditure is increased by increasing
physical activity
 Walking at moderate speed increases the energy
expenditure to 300 kcal/hour
 The energy expenditure during brisk walking,
running, swimming and heavy exercise is 500 to
600 kcal/hour

 The energy intake should be reduced to 1,000
kcal/day until the ideal body weight or BMI is
achieved
 Protein intake should be maintained at 1 gm/kg of
body weight
 Fats should provide about 10 percent energy, and
should be in the form of vegetable oils rich in
essential fatty acids

 The remaining calories should be provided by
carbohydrates
 Intake of sugar and jaggery should be restricted
to 15 gm/day or less
 Potatoes and sweet potatoes should be excluded
from the diet
 Other vegetables, raw, boiled or steamed, may
be taken as desired

 200 to 250 gm of fruits and 400 ml of skimmed
milk should be included in the daily diet
 Vitamin supplements may be given in the form of
one multivitamin tablet daily

DIET PRESCRIPTION
 Special dietary advice is required in some non-
nutritional disorders also e.g. diabetes mellitus,
coronary artery disease, liver diseases, kidney
diseases etc
 While giving dietary advice to a patient, some
points have to be kept in mind

 One need not be mathematically precise in
prescribing a diet
 There is considerable variation in the
composition of a given food item
 Efficiency of digestion, absorption and
metabolism also vary from person to person
 Therefore, absolute accuracy is impossible to
achieve

 Quantities of food items should be prescribed in
terms of usual serving measures, e.g. teaspoon,
tablespoon, cup, glass etc, and not in terms of
gm or ml as a patient is unlikely to weigh or
measure food items
 The cost of food items and purchasing power of
the patient should always be kept in mind

 It is always possible to substitute a costly
fruit with a cheaper one or a costly vegetable
with a cheaper one without
compromising the nutritional value
 One should also enquire whether a patient is
allergic to some food

Diabetes Mellitus
 Diet control is one of the cornerstones in the
treatment of diabetes mellitus
 Many mild to moderate diabetics can be controlled
by diet alone
 One of the important considerations while
recommending diet is the weight of the diabetic
patient
Diabetes Mellitus
 Diet control is one of the cornerstones in the
treatment of diabetes mellitus
 Many mild to moderate diabetics can be controlled
by diet alone
 One of the important considerations while
recommending diet is the weight of the diabetic
patient

 The weight should be brought to, and maintained,
as near the ideal body weight as possible
 An underweight diabetic should gain weight and
an over-weight diabetic should lose weight until
the ideal body weight is attained
 Total energy intake is more important than the
proportions of proteins, carbohydrates and fats

 Intake of saturated fatty acids and cholesterol
should be restricted as diabetics are relatively
more prone to atherosclerosis
 Intake of mono- and di-saccharides should also
be restricted as these lead to sharper elevations
of blood glucose than polysaccharides

 In drug-dependent diabetics, timing and
carbohydrate content of meals are important
 Missing or delaying a meal or taking insufficient
carbohydrate after taking an antidiabetic drug can
cause hypoglycaemia which may sometimes be
fatal

Diet for an underweight diabetic
 The total energy intake should be 2,400 kcal/day
which should come from 90 gm of proteins, 350
gm of carbohydrates and 70 gm of fats
 Visible fat intake should be about three
tablespoons a day, preferably in the form of
vegetable oils

 Sugar and jaggery should not exceed four
teaspoons a day
 The daily milk intake should be five cups of
skimmed milk or three cups of whole milk

Diet for an overweight diabetic
which come from 225 gm of carbohydrates, 65
gm of proteins and 30 gm of fat
 The daily ration of visible fat is one tablespoon
 Sugar and jaggery is excluded

 The milk ration is three cups of skimmed milk a
day
 To produce a feeling of fullness, intake of
vegetables, salads and low-carbohydrate fruits
may be increased

Liver Diseases
 Liver is a major site for metabolism of
carbohydrates, lipids and proteins
 Therefore, the diet has to be modified in a
number of liver disorders
 Major hepatic disorders which require diet
readjustments are cirrhosis of liver, hepatic or
obstructive jaundice and hepatic precoma or
coma

Cirrhosis of liver
 A high-calorie, high-protein diet is required for
regeneration of liver but the patient is unable to
take large meals because of poor appetite and
sub-normal hepatic function
 A diet providing 2,000 kcal/day can usually be
tolerated by the patient

 These should come from 110 gm of proteins, 290
gm of carbohydrates and 45 gm of fat
 Vitamin supplements are usually required
 If the patient has oedema, salt should not be
added to food

Jaundice
 In moderate to severe hepatic or obstructive
jaundice (serum bilirubin exceeding 15 mg/dl),
protein intake is restricted to decrease the
production of ammonia, and fat intake is restricted
as the patient is unable to digest, absorb and
metabolise it

 The total energy intake should be about 1,700
kcal/day which should come from 40 gm of
proteins, 25 gm of fat and 325 gm ocarbohydrates
 The total ration of visible fat is one tablespoon a
day
 Total ration of milk is two cups of skimmed
milk/day
 Egg, meat, chicken, fish, pulses and nuts are
totally excluded

Hepatic pre-coma and coma
 Severe viral hepatitis and cirrhosis can lead to
hepatic pre-coma which may culminate into coma
 The patient is unable to eat
 Hence, the feeding has to be parenteral or
through a nasogastric tube

 Nasogastric tube feeding is preferable as it is
easier and cheaper
 Protein and fat are completely withheld

 The following solution may be given by
nasogastric tube every six hours -
Glucose or cane sugar : 75 gm
Vegetable soup : 100 ml
Fruit juice : 100 ml
Sodium chloride : ½ teaspoon
Potassium chloride : ½ teaspoon
Liquid multivitamin syrup : 1 teaspoon
Water, to make : 500 ml

Kidney Diseases
 Dietary modifications are required in renal failure
and nephrotic syndrome
 In renal failure, protein intake is restricted as the
kidneys are unable to excrete urea
 In nephrotic syndrome, extra proteins are
required as there is excessive loss of proteins in
urine

Renal failure
which should come from 30 gm of proteins, 60
gm of fat and 260 gm of carbohydrates
 The intake of visible fat should be two
tablespoons a day, and milk, three cups a day

 Egg, meat, fish, pulses, nuts and beans are totally
excluded
 If there is edema or hypertension, no salt should
be added during cooking

Nephrotic syndrome
 A diet providing 2,100 kcal/day is recommended
 These calories should be provided by 110 gm of
proteins, 70 gm of fat and 260 gm ocarbohydrates
 Intake of visible fat should be two tablespoons a
day
 No salt should be added to the food

Coronary Artery Disease
 A patient with coronary artery disease is likely to
be obese and with elevated serum cholesterol
 Therefore, the weight should be reduced until
ideal body weight is reached by giving the diet
advised for obesity

 To reduce serum cholesterol, butter, cream, egg
yolk and organ meats should be excluded from the
diet
 Fish is preferable over meat and chicken
 When body weight becomes normal, carbohydrate
intake should be gradually raised to a level that
doesn’t increase body weight

Hypertension
 A hypertensive patient is also generally obese, and
is prone to coronary artery disease
 Therefore, the dietary guidelines for coronany
artery disease apply to hypertension also
 In addition, salt restriction is also required in
hypertension

Peptic Ulcer
 Peptic ulcers can occur in stomach or duodenum
 Hypersecretion of gastric hydrochloric acid was
believed to be a major factor in causation and
aggravation of peptic ulcers

 Peptic ulcer patients were earlier advised to take
a bland diet consisting mainly of milk and
cream so as not to stimulate gastricacid secretion
 Later evidence showed that most of the peptic
ulcers are caused by H.pylori infection
 The only dietary advice given now a days is
avoidance of coffee and alcohol, and any food
that aggravates the symptoms

Nutrition and Diet.ppt

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