This document discusses nutrition and health. It begins by defining nutrition and outlining its significance for health and disease prevention. Undernutrition contributes to many child deaths globally and malnutrition rates in India are high. Diet is associated with both chronic and infectious diseases. The document then covers topics like food and nutrients, dietary standards including recommended dietary allowances, reference individuals, classification of foods, and proximate principles of foods like proteins, carbohydrates and fats.

1. Nutrition and Health
Dr Utpal Sharma
Demonstrator
Department of Community Medicine
FAAMCH, Barpeta

2. Introduction
 The term ‘Nutrition’ is derived from a Latin word nutritic,
meaning nourishment .
 Nutrition can be considered to be the foundation of good
health and freedom from disease.
 Definitation goes…….‘The science of foods, nutrients and
other substances therein; their action, interaction and balance
in relationship to health and disease; the processes by which
the organism ingests, digests, absorbs, transports and utilizes
nutrients and disposes off their end products…”
 Simply put the word nutrition is used to refer to the processes
of the intake, digestion and assimilation of nutrients resulting
in maintainence health and combat disease.

3. Significance of nutrition
Adequate nutrition is required for growth, development and
maintenance of normal functions
Under nutrition contributes to 60% deaths amongst under five
children (WHO, 2002)
More than 85% children in India suffer from malnutrition(44%
Mild malnutrition, 38% moderate malnutrition and 4.6%severe
malnutrition) (Gomez classification, NNMB 2007)
About 55% men and 75% non pregnant non lactating women are
anemic
Epidemiological data shows strong association between under
nutrition and morbidity / mortality

4. Cont….
Chronic degenerative disorders such as coronary
artery disease, hypertension, type 2 diabetes,
certain cancers, etc. are related to diet and
nutritional status
Obesity is associated with higher risk of developing
cancer breast, colon, endometrium, gallbladder,
esophagus, pancreas, etc.
Consumption of foods rich in dietary fibre and
antioxidants is associated with reduced risk of
certain cancers
Under nutrition during foetal and early childhood is
known to be associated with chronic degenerative
disorders in later life

5. Wise words…..

6. Food and Nutrients
Food
 Food is a substance eaten or drunk to maintain life and growth.
 Diet, on the other hand is what a person habitually eats and drinks.
Nutrients
 The nutrients are chemical substances that are present in the food
we eat.
 The important nutrients are proteins, fats, carbohydrates, vitamins
and minerals.
 Foods contain various nutrients in different proportions.

7. Fundamentals of nutrition
Nutrition
 Is a science of food and its relationship to health
 Defines all aspects of interaction between a living organism and the
substances which help the organism to grow and sustain itself.
 There being three types of living organisms, nutrition may be said to
have different specialities, viz., plant nutrition, animal nutrition and
human nutrition.
Human nutrition
 Deals with food and nutritional requirements of human beings at
different age, sex and physiological status, nutritional imbalances in
human beings and various measures for overcoming such
deficiencies and imbalances.

8. Cont…
Clinical nutrition
 Is that branch of human nutrition dealing with the
physiological, pathological and therapeutic aspects of
nutrition.
Public health nutrition
 Is the branch of human nutrition dealing with human health
and the services necessary to maintain human health.
 Efforts through national health services and other health
related agencies and institutions to promote human nutrition.
Community nutrition
 To promote human nutrition. Community nutrition is same as
public health nutrition.

9. Why do we eat food?
 We eat to satisfy hunger (satiety) and to get energy for our day to
day functioning. Food serves many functions in the body :
 Food regulates body processes
 Temperature control of the body (calories),
 Control of osmotic pressure (proteins and electrolytes),
 Maintenance of hydrogen ion concentration (ph through electrolytes),
 Solvent power of fluids (proteins and water),
 Nerve conduction (minerals),
 Muscle elasticity (minerals),
 Innumerable metabolic processes (vitamins and minerals).
…….. All these processes are regulated by the ‘fuel’
supplied through food e.g.

10. Cont…
Food builds body tissues :
 The structural materials of food, proteins, minerals, vitamins
and water are needed for growth and development.
 The food is also needed for the maintenance of the cells and
tissues.
Food supplies energy :
 The macronutrients (carbohydrates, proteins and fats) provide
constant source of fuel to the body.
Food gives us enjoyment :
 The community faces major nutritional problems from the
consumption of inadequate or imbalanced diet. This is true for
both healthy and sick

11. The Interplay between Malnutrition and
Infection
It is a vicious cycle that is difficult to break in the setting of poverty, ignorance
and lack of health services.

12. Nutrients and Proximate
Principles of Food
 Food consists of seven main components—
 CARBOHYDRATES,
 FATS,
 PROTEINS,
 VITAMINS,
 MINERALS,
 WATER AND
 FIBER.
 These components provide the six types of nutrients essential for
human body, viz. energy, protein, vitamins, essential fatty acids,
minerals and water.
 Fiber, though not labeled as a nutrient, is important component of
food and its deficiency gives rise to various disease syndromes.
 The basic role of fats and carbohydrates in nutrition is similar, i.e. to
act as source of energy.
 It is true that fats also supply the essential fatty acids, but the
deficiency of the latter is rare.

13. Classification of food
Classification by origin
Foods of animal origin
Foods of vegetable origin
Classification by chemical composition
Proteins
Carbohydrates
Fats
Vitamins
Minerals

14. Cont…..
Classification by predominant functions
 Body building foods e.g milk, meat, poultry, fish, eggs etc
 Energy giving foods e.g. cereals, sugars, roots tubers, fas and oils
 Protective foods e,g. vegetables, fruits, milk
Classification by nutritive value
 Cereals and millets
 Pulses (lugumes)
 Vegetables
 Nuts and oilseeds
 Fruits
 Animal foods
 Fats and oils
 Sugar and jaggery
 Condiments and spices
 Miscellaneous foods

15. Variability in Nutritional Requirements
 Even though there is a concept of standard requirements and
intakes, it must not be forgotten that each person has unique
nutritional requirements.
 This is because each one of us has a unique genetic make up and
body biochemistry.
 A nutrient intake sufficient for one person may be inadequate for
other.
 Besides these genetic differences, many other factors can also alter
daily requirements, including age, environment and life style
choices.
 Factors as diverse as pregnancy, lactation, sports training, smoking
and pollutant can cause nutritional needs to vary.

16. Factors altering the daily requirement of
nutrients
Biochemical individuality Genetic differences
Gender Pregnancy
Lactation Growth
Infections Other diseases
Surgery Drug-Nutrient interaction
Smoking Alcohol
Caffeine Environmental pollutants
Activity Exercise level
Diet factors e.g. intake of : Carbohydrates; Fat; Fibre; Proteins

17. Dietary Standards
Concept of Recommended Dietary Allowance (RDA)
 It is extremely important to plan the rations and food supplies
for various groups, may it be the general community or a
specialized group like the armed forces, a school or a prison.
 For such a planning we must have a set of standard
allowances that are universally acceptable and followed.
 The first such example (for cereals) can be traced back to
ancient Rome .
 The concept of various macro-nutrients first evolved in the
nineteenth century.
 At that time the dietary requirements were stated in terms of
nutrients rather than foods.
 In the early twentieth century vitamins came on the landscape
and their requirements were also worked out and stated

18. More of RDA….
 The RDA of a nutrient is the amount (of that nutrient) sufficient for
the maintenance of health in nearly all people.
 These are the estimates of nutrient intakes which individuals in a
population group need to consume to ensure that the physiological
needs of all subjects in that population are met.
 It is an estimate that corresponds to mean intake of the given
nutrient + 2 Standard Deviation (that is about 25% of the mean has
been added).
 It covers the requirement of 97.5% of the population. This is the safe
level of intake and the chances of this level being inadequate is not
more than 2.5%.
 This ‘safe level’ approach is however not used for defining the
energy requirement, as any excess of energy intake is as
undesirable as its inadequate intake.
 Hence for defining the RDA of energy only the average requirement
is considered.

19. Can the RDA be Applied to
Individuals?
 RDA is the mean requirement for a nutrient (except energy),
to which an allowance of 2 SD has been added.
 There are several individuals in a population whose
requirement is actually well below or above the RDA.
 If all the students in a class of 100 were to eat food exactly as
per their RDA about half would loose and the other half would
gain weight, to the extent of being seriously undernourished
or obese after a year! ……
……. because the RDA for energy is a catering average;
individuals however consume as per their appetite, which
follows their energy expenditure.
 The RDA can therefore, not be used as standard to determine
whether or not a given individual’s requirement of a nutrient
has been met.

20. Cont…
 It is therefore important to keep the principles of probability in mind
and be cautious, when applying RDA at an individual level .
 RDAs provide a standard against which the nutrients in the food
eaten by a section of the community /country can be assessed.
 It is thus possible to find out a group with a low intake of a particular
nutrient. Further nutritional investigations are then mounted to go
into the details and suitable measures can be recommended.
 Similarly, RDAs are the starting point for the food and economic
planning for the agricultural, economic and food sectors.
 The national level food balance sheets are prepared keeping the
RDAs in mind.

21. Reference Man and Woman
 The final goal of all nutritional policies is to provide adequate
nutrition to attain full genetic potential for growth and development.
 It is important that the ideal/ desirable weights and heights are
considered to recommend nutrient intakes.
Reference Indian Adult Man :
 Between 18-29 years of age and weighs 60 Kg with a height of 1.73
m with a BMI of 20.3
 He is free from disease and physically fit for work.
 On each working day he is employed for 8 hours in occupation that
usually involves moderate activity.
 While not at work he spends 8 hours in bed,4-6 hours sitting and
moving about and 2 hours in walking and in active recreation or
household duties.

22. Cont….
Reference Indian Adult Woman :
 Is between 18 and 29 years of age, non-pregnant non-
lactating (NPNL)
 Weighs 55 kg with a height of 1.61 m and a BMI of 21.2
 Free from disease and physically fit for active work.
 She may be engaged in general household work,
 in light industry or…..
 ….in any other moderately active work for 8 hours.
 While not at work she spends 8 hours in bed,
 4-6 hours sitting and moving about in light activity and
 2 hours in walking or
 active household chores.

23. Proximate principles
of food

24. Introduction
 The human body requires various nutrients for survival, maintenance of
health and to prevent disease.
 Proteins, fats and carbohydrates are the ones which form the backbone of
the nutrients in terms of quantity and these are termed as the proximate
principles of food.
 Energy for basal functions, work metabolism and heat for maintenance of
body temperature is produced by the oxidation of carbohydrates, fats and
proteins.
 The intake of food is normally balanced by hunger which thus, indirectly
balances energy expenditure however there are exception in states like
malnutrition
 Moreover, hunger can be modified by enough intake of food and also by
doing less muscular work.
 Absence of hunger is not, therefore, necessarily an index of an adequate
food intake.

25. Energy
 Energy is required for maintaining the body temperature and vital
activity of organs, for mechanical work and for growth.
 Even at complete rest and no physical work, energy is required for
the activity of internal organs and to maintain the body temperature.
 This energy is required for maintaining the basal or resting
metabolism.
 Age, sex, height, weight and state of nutrition of the individual are
some of the factors that influence it.
 Basal Metabolic Rate (BMR) is determined experimentally when
the subject is lying down at complete physical and mental rest,
wearing light clothing in a thermo-neutral environment and in the
post absorptive state (at least 12 hours after the last meal).
 The BMR is related more closely to lean body mass (fat free body)
rather than to the surface area.

26. Unit of energy
 Calorie is the basic unit of energy. Kilo calorie is the heat
required to raise the temperature of 1 Kg of water by 1°C.
 The Joule (J) is the SI unit of energy. It is energy expended
when one kilogram is moved one meter by a force of one
Newton (N).
 Since Joule is too small unit to describe the energy value of
diet, kilo Joule (KJ) and mega Joule (MJ) are more practical
 However, the old unit of energy, namely, kilocalorie (Kcal) has
been in use in nutrition for a long time and is still being used.
 For conversion, 1 Kcal = 4.184 KJ and 1 KJ = 0.239 Kcal.

27. Proteins
 Proteins are large molecules made up of nitrogen containing amino
acids that are united together by peptide linkages.
 In adults approximately 16% of body weight is attributable to
proteins and is next to water as the major component of body
tissues.
 Proteins are indispensable constituents of living protoplasm as they
participate in all vital processes.
 A total of 22 aminoacids are now known to be physiologically
important for the human body.
 Under proper conditions, the body is capable of synthesizing some
of these amino acids, with adequate nitrogen called
NONESSENTIAL amino acids.
 Others cannot be synthesized by the body and must therefore be
supplied in diet are ESSENTIAL amino
 To these may be added histidine which appears to be essential for
the growth of infants

28. Sources of proteins
There are two main dietary sources of
proteins :
Animal Sources : These include eggs,
milk, meat and fish
Vegetable Sources : Pulses, nuts,
cereals, beans and oilseed cakes

29. Functions of Proteins
 Proteins are important for body building, growth, repair and
maintenance of body tissues
 Required for the synthesis of plasma proteins, haemoglobin,
enzymes and hormones
 Proteins like collagen, actin and myosin form the structural tissues -
skin and muscles
 Proteins act as transport carriers for many molecules like iron,
haemoglobin, lipids etc.
 Antibodies are also proteins. Proteins are involved in the acute
phase of inflammation as well
 Albumin, a protein, acts as a buffer in the maintenance of blood pH
 May at as a source of energy in lean time providing around 4 Kcal/g

30. Quality of Proteins
 The nutritive value of a protein depends upon its amino acid
composition.
 A biologically complete protein is one which contains all the
essential amino acids in adequate amounts to meet human
requirements.
 Proteins from foodstuffs of animal origin, such as milk, meat and
eggs are biologically superior to proteins of vegetable origin.
 Most of the vegetable proteins lack one or more amino acid and are
thus classified as biologically incomplete proteins.
 The short essential AA in a food item is known as the limiting
amino acid, e.g.the limiting amino acid in wheat is lysine and in
pulses it is methionine.
 The quality of vegetable proteins in a vegetarian diet can be
improved by providing a suitable combination of vegetable proteins.

31. Cont…
 Lack of a particular amino acid in one protein can be compensated
by simultaneous consumption of another protein, containing that
limiting amino acid…….this is known as supplementary action.
 Combination of wheat products e.g. bread (chapati) with pulses (dal)
will compensate for these deficiencies (of lysine and methionine).
 Quality of a protein is worked out in terms of Biological Value,
Digestibility Co-efficient, Net Protein Utilization And Protein
Efficiency Ratio.
 The net protein utilization (NPU) is the most commonly used
parameter.
 A protein with an NPU of more than 65 is considered as of optimum
quality.
 Egg protein is considered to have NPU of 100 and considered ideal
or reference protein against which other proteins are compared with.

32. RDA for proteins
 The requirement of proteins is generally accepted to be 1g/ Kg/day
for adults.
 So the recommended dietary allowance for a reference adult male
works out to 60g/day and for a reference adult female it is 50g/day.
 An additional allowance of 15g/day is recommended for pregnancy.
 During lactation an extra allowance of 25g in the first 6 months and
18g in the subsequent 6 months is recommended.
 Deficiency can occur when the diet does not provide enough protein
in relation to the requirement which may be high as in the case of
young growing children.
 Secondly, if energy intake is insufficient proteins will be diverted to
produce energy and thus causing a deficiency of proteins.
 Childhood infections (esp. measles) also play an important role in
triggering and sustaining a long term protein deficiency.

33. Recommendations on Diet for Proteins
 Eat nutritionally balanced diet to get adequate protein
 Meat and fish are good sources
 Vegetarians must eat proper combination of plant proteins from
both cereal and pulses groups
 Include Soyabean in your diet
 Two to three servings of protein-rich food must be ensured every
day
 One serving may be equivalent to :
 One to two cups of cooked meat, poultry, fish
 Half cup of cooked dry beans/ lentils/ legumes
 One egg
 Handful of fried/roasted- salted groundnuts
 Handful of roasted Bengal grams

34. Fats
 Fats are organic compounds (chemically triglycerides),
insoluble in polar solvents (water) but soluble in organic
solvents such as ether, chloroform and benzene.
 These are actual or potential esters of fatty acids.
 Fats are only distinguished from oils by their different melting
points; fats are solid and oils liquid at room temperature.
 ‘Fats’ and ‘oils’ are the ones used in kitchen and ‘lipid’ is the
term used by biochemists.
 However, the general term fat is commonly used to refer to
the whole group and is used interchangeably with lipids.

35. Sources of fats
Animal Sources :
 They are milk and milk products (ghee, butter),egg and fish
oils.
 Animal fats are poor sources of essential fatty acids except
for certain marine fish oils viz. cod liver oil and sardine oil
 They are good sources of retinol and cholecalciferol.
Vegetable Sources :
 Various edible oils such as groundnut, mustard, cottonseed,
safflower, rapeseed, palm and coconut oil.
 Vegetable oils with the exception of coconut oil are all rich
sources of essential fatty acids
 They lack retinol and cholecalciferol except red palm oil which
is rich in carotenoids.

36. Visible and Invisible fats
 Fats used as such during cooking are termed as “visible” fats….
……..and that present as an integral components of
various food are referred to as “invisible” fat.
 Hydrogenated oils and margarine would also be classified as visible
oils.
 These are the major sources of fats in our diet.
 Chemically they are triglycerides of fatty acids and could be
saturated or unsaturated.
 It is now believed that the bare minimal requirement of visible fats to
meet the essential fatty acid requirements is 15 to 25 g per day.
 The upper limit is fixed at 30% of the total energy intake or less
than 80 g / day.

37. Cont….
 Some amount of fat is present in all food stuffs.
 From the nutritional standpoint, important of them are cereals,
pulses, oilseeds, nuts, milk, eggs and meat.
 This invisible fat contributes substantially to the total fat
consumption and essential fatty acid intake of our diet.
 Cereals and pulses perceived to be poor in fats contribute
significantly towards fat intake of a Indian diet.
 This is because most Indians depend on the ‘staple’ of
cereals, consumed in a large quantity.
 The invisible fats may account for 20 to 50% of all fats
consumed, depending on the type of diet.
 It should however contribute to not less than 6% of total
energy or about 15g of invisible fats per day.

38. Types of Fatty Acids
 Fatty acids composes straight hydrocarbon chain with one
methyl group and terminating with a carboxylic acid group.
 Hydrogen atoms are attached to the carbon chain….
……. number of hydrogen atoms determines the degree
of saturation of the fatty acid.
 A fatty acid with hydrogen atoms on every arm is said to be
‘saturated’.
 Unsaturated fatty acids contain double carbon bonds where
there is no hydrogen.
 If there is only one double bond, the fatty acid is termed as
monounsaturated
 More than one double bond in the fatty acid will be termed as
polyunsaturated.

39. Cont…
Saturated Fatty Acids (SFA) :
 Saturated Fatty acids have a relatively high melting point and tend to
be solid at room temperature.
 Obtained from animal storage fats and their products e.g. meat fat,
lard, milk, butter, cheese and cream.
 Fats from plant origin tend to be unsaturated with the exception of
coconut oil and palm oil.
 High intake of SFA is associated with an increase in LDL and total
cholesterol and thus increases the risk of atherogenesis and
cardiovascular disease.
 Some examples of SFAs are Myristic acid, Palmitic acid and
Stearic acid.

40. Cont…
Monounsaturated Fatty Acids (MUFA) :
 MUFA contain only one double bond and are usually liquid
(oil) at room temperature.
 Olive oil and rapeseed oil are good dietary sources of MUFA.
 MUFA are also present in meat fat and lard.
 Dietary MUFA does not raise plasma cholesterol.
 They lower LDL cholesterol without affecting the HDL e.g.
Oleic acid

41. Cont…
Polyunsaturated Fatty Acids (PUFA) :
 PUFA contain two or more double bonds and they too are liquid at
room temperature.
 They are easily oxidized in food and in the body.
 PUFA have a vital role in immune response, blood clotting and
inflammation.
 PUFA are divided into omega-3 (ω3) (found in fish and fish oils )or
omega 6 (ω6) groups of PUFA.
 The health benefits of these include reducing the cardiovascular risk
factors and have beneficial role in cognitive function of brain.
 Some common omega-3 fatty acids are
 α-linolenic acid (linseed, soyabean, rapeseed, leafy vegetables),
 Eicosepentaenoic acid(marine algae, fish oils) and
 Docosahexenoic acid (fish oils).

42. Omega-3 Fatty Acids in Prevention and
Therapy
Coronary artery Disease (CAD) : Omega-3 (ω3) FA reduces
platelet aggregation, blot clot formation and thus atherosclerosis.
Chances of cardiac arrhythmias also go down, thus benefiting in CAD.
Hypertension : They lower the high blood pressure in hypertensives.
Hyperlipidaemia : They lower the high blood lipids (triglycerides and
total cholesterol), while increasing HDL-c.
Bronchial asthma : ω3 Fatty Acids reduce inflammation, frequency
and severity of asthma.
Diabetes : They lower TG, and reduce leakage of proteins from small
vessels, thus improving the overall metabolism and the diabetic state.
Autoimmune disorders : Omega 3-FA reduce pain, inflammation and
joint stiffness in rheumatoid arthritis and other autoimmune disease.

43. More about fats…..
Trans Fatty Acids (t-FA)
 Trans fatty acids rarely occur in nature.
 These are produced during the partial hydrogenation of
PUFA.
 In Indian homes this process takes place commonly when oil
is heated over and over again e.g process of frying puri,
pakori or samosa etc. Heating same oil repeatedly.
 Trans fatty acids have been associated with adverse effects
on lipoprotein status by elevating LDL and depressing HDL.

44. Essential Fatty Acids (EFA)
 If fats are entirely excluded from the diet, retarded growth,
dermatitis, kidney lesions and an early death might result.
 Studies have shown that feeding of certain unsaturated fatty acids
e.g. linoleic and linolenic acid is effective in curing the condition.
 Hereby certain unsaturated fatty acids cannot be synthesized in the
body and must be acquired from diet (Essential fatty acids).
 EFA are commonly found in plant and fish oils.
 The EFA requirement is 3-6% of the total energy intake depending
on the age and physiological status of the individual.

45. Cholesterol…..the mystery…!!
 Cholesterol is always talked as if it is the hazardous abnormal fat.
 It is considered by many as a type of a saturated fat but it is only a fat
related compound.
 Chemically it falls under the group of sterols.
 It is named after the body material where it was first identified, the
gallstones (Greek, chole, bile; steros, solid)
Synthesis :
 It is synthesized only in the animal body.
 All plant products are free of cholesterol.
 The human body synthesizes indigenous cholesterol primarily in liver
(but also in adrenal cortex, skin, intestines, testis and ovaries), for
sustaining life.
 It is a normal constituent of bile and a principal part of the gall stones

46. Cont…
Sources :
 The important dietary sources are egg yolk, meat (liver and kidney).
RDA :
 Since it is synthesized indigenously in the body, there is no dietary
requirement of cholesterol.
 However, the upper limit of cholesterol consumption has been put at
300mg per day
Functions :
 It is vital as a precursor to various steroid hormones e.g. sex hormones
and adrenal corticoid hormones.
Hazards :
 In dysfunctional lipid metabolism, it is considered the major factor for
atherosclerosis.
 Epidemiological studies have linked high cholesterol intake to the
increased risk of coronary heart disease

47. Why fats in diet?
 The following aspects are important in considering the
recommendation for fat intake :
 The quantity of fat intake should be good enough so that
requirement of essential fatty acids is met.
 Absorption of fat soluble vitamins should not be compromised.
 Fat intake should be sufficient enough to make diet palatable.
 Some stores must be maintained in the body to tide over a
lean period.
 It should not be so much in quantity that it causes undesirable
effects on health.

48. Functions of Fats
 They are concentrated sources of energy providing about 37.7 KJ/g
or 9 Kcal /g.
 Fats serve as vehicle for fat soluble vitamins (A.D, E and K).
 Fats are structural components of cell and cell membrane.
 They are the sources of essential fatty acids. Linoleic acid and
arachidonic acid are precursors of prostaglandins which are
required for a wide variety of metabolic functions.
 Apart from their nutritional significance, fats improve the palatability
of diet, delay gastric emptying & raise the caloric density.
 Some fats can be converted to biologically active compounds such
as steroid hormones, interleukins, thromboxanes and prostaglandins
and bile acids (from cholesterol).

49. Recommended Dietary Allowance 0f Fats
 The RDA for adults is 20g of visible fat per day.
 For pregnant and lactating women it is 30 and 45 g respectively.
 Fat content of diet should not exceed 20 to 30% of the total calories
consumed.
 Intake of PUFA should be 8 to 10% of energy intake remaining 8 to
10% can be derived from mono-unsaturated fatty acids
 The dietary cholesterol should be limited to 300 mg/day.
 Excess fat is dangerous on two accounts….
 First, in case it is consumed in a higher quantity and….
 ….Secondly if the wrong quality of fat is consumed.

50. Nutritional aspect of fats
Quantity of Fat :
 Higher calories lead to obesity and many other lifestyle diseases.
 A high level of fat in diet is notorious in the causation of atherosclerosis and
so is a major risk factor for coronary artery disease and strokes.
 Any amount that contributes to more than 30% of total calorie intake is
considered as high.
 Low physical activity and sedentary lifestyle further augment the risk.
Quality of Fat :
 High levels of saturated fatty acids are more dangerous.
 A proportionately higher content of PUFA is found to be protective for CVD.
 High levels of LDL are associated with higher atherosclerotic risk so LDL is
colloquially known as ‘bad cholesterol’.
 A high level of HDL has favourable effect on the cardiovascular system and
is termed as ‘good cholesterol’.

51. Carbohydrates
 Carbohydrates are the basic source of fuel to run life on earth.
 It is these carbohydrates into which the energy from sun is
converted through the process of photosynthesis by plants.
 In fact this is the energy that is used by all living organisms.
 Thus carbohydrates can be considered as the very ‘basis’ of life.
 Chemically carbohydrates are polyhydroxy aldehydes or ketones,
or substances that produce such compounds when hydrolyzed.
 Contain carbon, oxygen and hydrogen in proportion as a ‘hydrate of
carbon’ (CH2O), hence the term Carbohydrate.

52. Classification of proteins
 From the nutritional or functional point of view, carbohydrates can be
divided into two categories.
 Available carbohydrates :
 These are the carbohydrates which can be digested in the upper
gastrointestinal tract, absorbed and utilized.
 Polysaccharides such as Starch, Dextrin And Glycogen
 Disaccharides such as Lactose, Sucrose And Maltose
 Monosaccharides such as Glucose, Fructose And Galactose.
 Dietary Fibre :
 Comprises of unavailable carbohydrates or dietary fibre, which are
difficult to digest.
 These are cellulose, hemicellulose, gums, pectins etc.

53. Sources of Carbohydrates
 The major source of dietary carbohydrates in an Indian set up is starch from
cereal grains, millets, legumes, roots and tubers .
 With increasing prosperity as in industrial societies, sugar has replaced
complex carbohydrates as the main source.
 The presence of monosaccharides (free glucose or fructose) is limited to
fruits and vegetables, fructose is found in honey, fruits and vegetables.
 Sucrose and Lactose are the commonest disaccharides.
 Sucrose is extracted from sugar cane it gets hydrolysed into glucose and
fructose.
 Lactose is found in milk it gets hydrolysed to glucose and galactose.
 Maltose is present in malted wheat and barley other sources are nuts and
seeds.

54. Functions of Carbohydrates
 Most significant and cheapest source of energy in the
diet comprising 60 to 85% of energy in our Indian diet
supplies around 4 Kcal/g energy.
 This translates to about 360 to 400g carbohydrates for
a 2400 Kcal diet.
 Various kinds of sugars (glucose, fructose, sucrose
etc.) imparts the sweet taste to life.
 Plays important role in metabolism wherein glycogen
resources in the muscles and liver are in a state of
dynamic exchange with the energy balance (of intake
and expenditure) through the liver.

55. Cont…
 A constant supply of carbohydrates has a Protein
sparing action and Proteins are not required to be
broken down for energy.
 Similarly fats are also spared to be used up if enough
carbohydrate supply is maintained.
 The brain exclusively uses glucose and is dependent
on its constant supply for its functioning.
 Fibre ( a carbohydrate), has the important function of
increasing faecal bulk, stimulating peristalsis and
blocking cholesterol synthesis in liver.

56. Problems Due to Deficiency and Excess
 A deficiency of carbohydrates in diet not compensated by other
nutrients, a situation of energy deficiency sets in.
 This is typically seen in infants and children wherein protein calorie
malnutrition is not uncommon.
 A similar situation of energy deficiency in food deprived people in
cases of starvation encountered in famines and droughts.
 Anorexia nervosa is a major psychological condition, wherein the
patient doesn’t eat food and ends up being cachexic.
 A very low carbohydrate diet results in utilization of other
macronutrients (lipids and proteins) for energy and result in
production of ketone bodies (ketosis).
 Eventually bone mineral loss, hypercholesterolaemia and
increased risk of urolithiasis may result.

57. • Consumption of an excess of carbohydrates
seems to be a bigger problem in the present day
scenario of progressive economies.
• If the intake is large enough to provide excessive
calories such an individual ends up being obese
and might fall prey to a host of lifestyle diseases.
• It is interesting to note that excess of even few
calories per day (100-200 Kcal) over a couple of
months accumulates enough calories to cause
obesity.

58. Dietary fibre….
 Fiber is broadly classified into two groups
Insoluble form
 Wheat bran, an insoluble form is a good stool softener
 Insoluble form increases the bulk of stool and speeds their passage
through the gut.
 Whole grains such as oats and wheat bran, and skin of many fruits,
vegetables are good sources of insoluble fiber.
Soluble forms
 Soluble form is a good absorber of cholesterol, as it forms a gel
while passing through digestive tract.
 Some hemicellulose, betaglucans and other compounds found in
oats, legumes, brocolli and fruits are good source of soluble fiber.

59. Dietary Fibre in Health and Disease
 Fibre helps in achieving prevention of cardiovascular disease
through various mechanisms
 Soluble fibre binds with bile acids and alters the quantity of
cholesterol or fatty acids absorbed.
 The re-absorption of bile acids is slowed by soluble fibre to
increase cholesterol losses in faeces.
 Intestinal bacteria reduce soluble fibre to short chain fatty acids
which block cholesterol synthesis in the liver.
 Fibres also help in the maintenance of weight and prevention
of obesity.

60. Cont…
 Soluble fibre blunts the response of blood glucose through
prevention of direct glucose absorption in the gut, helps in the
control of hyperglycaemia.
 Soluble and viscous fibres (pectin and gums) have the greatest
hypoglycemic effect
 Fibre is also considered to be an important contributory factor to the
prevention of colonic cancer
 In addition, fibre increases faecal bulk and relieves constipation
hence reduces the incidence of colonic cancers, diverticulitis and
appendicitis.
 The alteration in cholesterol production and further metabolism
reduces the formation of gallstones as most of them are of
cholesterol origin.

61. Energy requirement for reference Indian males and
females