The document outlines essential nutrients necessary for life, categorizing them into macronutrients and micronutrients, as well as essential and non-essential types. It details the various classes of carbohydrates, lipids, and proteins, their food sources, physiological functions, digestion, absorption, and metabolism, while also discussing the importance of these nutrients for overall health. Additionally, it emphasizes the recommended intake levels and potential health implications related to inadequate or excessive consumption of these nutrients.

2. NUTRIENTS

3. Objective
After Completing this chapter the students is able to
 Recognize essential nutrients for life function
 Describe the characteristics, types, physiological functions,
and food sources of essential nutrients
 Explain recommended intakes and the adverse effects of
both inadequate and excessive intake of nutrients
3

4. Introduction
 Nutrients are substances found in food that gives us
nourishment. We take them from the foods we consume
or the different types of liquid we drink.
 There are six classes of nutrients found in the food.
1. Carbohydrate
2. Lipids (Fats and Oils)
3. Protein
4. Vitamins
5. Minerals
6. Water 4

5. Introduction…
 Nutrients can be assigned to three functional categories.
5
Nutrient classes that
provide energy
Promote growth,
development, and
maintenance
Regulate body
processes
 Most
carbohydrates
 Proteins
 Most lipids
 Protein
 Lipids
 Some vitamins
 Some minerals
 Water
 Protein
 Some lipids
 Some vitamins
 Some minerals
 Water

6. Types of Nutrients
 Based on the amount needed each day
1. Macro Nutrients
2. Micro Nutrients
 Based on the ability of the body to synthesize
1. Essential Nutrients
2. Non-Essential Nutrients
6

7. Macro and Micro Nutrients
1. Macro Nutrients
 Nutrients required in large amount.
 i.e. Carbohydrates, Proteins, Lipids, and Waters.
 Mainly include calorie nutrients.
 Requirements daily given in a gram/day
 Micro Nutrients
 Nutrients required in small amount.
i.e. Vitamins and Minerals.
 Requirements daily given in a milligram or microgram/day.
7

8. Essential and Non-Essential Nutrients
8
Essential nutrients Non- Essential nutrients
 The nutrients required for
normal body functioning
that cannot be synthesized
by the body.
 Example: Essential fatty
acid (α-linolenic, linolenic)
Most vitamins…etc.
 The nutrients that can be
synthesized by the body
may also be absorbed from
foods.
 Examples: Vitamin D,
Cholesterol, most fatty
acids…etc.

9. Introduction
9

10. Carbohydrates
 It is an organic class of compounds found in nature
abundantly.
 Contain the elements C, H and O.
 The term “Carbohydrate” came from fact that these
compounds could be written as “hydrates of carbon” .
 The name derived from the general formula (CH2O)n
 Chemically can exists in food as simple sugar and
complex carbohydrates. 10

11. Classification of Carbohydrates
 Monosaccharides - simple sugar units that serve as the
basic unit of all carbohydrate structure.
 Disaccharides - 2 monosaccharides covalently linked.
 Polysaccharides - polymers consisting of chains of
monosaccharide or disaccharide units.
11

12. Monosaccharides
 Glucose, also known as dextrose
Major monosaccharide found in the body
It is the end product of other CHO
It is oxidized to produce energy, heat and carbon
dioxide, which is exhaled in breathing.
 Fructose also called Fruit sugar
Is the sweetest sugar
Convert to glucose in the liver
Galactose
 Not found freely in food, but it is found
combined together with Lactose.
 Convert to glucose in the liver 12

13. Disaccharides
 Sucrose also known as Table sugar
Composition of glucose + fructose
 Least expensive & most common
sweetener
 Lactose also known as Milk sugar
 Composition of galactose + glucose
 Used for food processing, milk & milk
production, and pharmaceutical Industries
 Maltose also known as Malt sugar
 Not found freely in food
 As an intermediate in digestion of Starch
 Produce in the process of malting
O
O
CH2
OH
H
H
O
H
H
OH
OH
H
H
O
HOH2
C
H
OH
H
H
O
H
CH2
OH
Glucose
glycosidic bond
Fructose
Sucrose
O
CH2
OH
H
H
O
H
OH
OH
H
OH
H
O
CH2
OH
H
O
H
H
H
OH
OH
H
H
Glucose
-glycosidic bond
Galactose
Lactose
O
CH2
OH
H
H
O
H
OH
OH
H
H
OH
O
CH2
OH
H
H
O
H
H
OH
OH
H
H
Maltose
-glycosidic bond
Glucose
Glucose

14. Polysaccharides
 Composed of many glucose molecule may contain 1000
or more glucose units are chiefly found in grains,
vegetables and fruits.
 Contains more than 10 monosaccharide units
 Few (oligosaccharides) or many (polysaccharides) glucose
units bound/linked together in straight or branched chains.
 Examples: Starch, glycogen
14

15. Polysaccharides…
Starch
 Major storage carbohydrate in
plants. They store in two forms
1. Amylose – long straight glucose
chains
2. Amylopectin – branched every
24-30 glucose residues
15

16. Polysaccharides…
Fiber
 A structural part of the plant composed of many sugar units.
1. Insoluble fibers are non viscous and are not digested by
intestinal bacteria.
These fibers are found in grains
Act as natural laxative
2. Soluble fibers are viscous and can be digested by intestinal
bacteria.
 These fibers are found in fruits and vegetables.
 Soluble Fibers have lower serum cholesterol level & reduce BGL in
Diabetics patient
16

17. Polysaccharides…
Glycogen
 The only form of CHO that animals
&human stored
 In most foods of animal origin it is a
negligible source of dietary carbohydrate.
 The glycogen in the liver used as a
reserve fuel and it serves between
meals and over night.
17

18. 18

19. Food Sources of Carbohydrates
 Free sugars are found from: fruits, juices, Soft drinks, , milk, sugar,
sugar cane, honey and yogurt, Cereal grains, Legumes & dried fruits,
vegetables, processed foods (pasta), pastries, breads, candies fruits like
banana, and sweet potato
 Starch is found from: starchy foods (like cereals and legumes and
potatoes), Other foods like fruits, vegetables, beans, nuts, seeds
 Oligosaccharides are found from : Garlic, onion, Whole grain cereals
and legumes (beans and peas)
 Non starch polysaccharides are found from: Fruits, vegetables,
Whole grain cereals and legumes 19

20. Food Sources of Carbohydrates…
20

21. Brain storming
Is juicing
healthier than
eating whole
fruit or
vegetables?
21

22. Carbohydrate Digestion
 Eating food doesn’t simply supply nutrients to body cells.
Digestion and absorption must occur.
 The enzymatic digestion of carbohydrates begins in the
mouth by Salivary amylase (Ptyalin) produced by the
salivary glands.
 No carbohydrate digestion takes place in the stomach.
22

23. Carbohydrate Digestion…
 Digestion occurs mainly in the small intestine through the
action of pancreatic and intestinal juices containing the
enzymes amylase, lactase, sucrase, and maltase.
 Maltose Two glucose molecule.
 Sucrose Glucose + Fructose
 Lactose Glucose + Galactose
 Carbohydrates that can be digested and absorbed in the
human small intestine are referred to as ‘glycemic’
carbohydrates. 23
Maltase
Sucrase
Lactase

24. Carbohydrate Digestion…
 Some plant polysaccharides in foods are resistant to
hydrolysis by human digestive enzymes and are referred
to as ‘dietary fiber’.
 These polysaccharides and the group of oligosaccharides
which are also not digested and absorbed in the small
intestine are described as ‘non-glycemic’ carbohydrates.
24

25. Introduction
25

26. Carbohydrate Absorption
 Carbohydrate mainly absorbed in Small intestine.
 Glucose & galactose- active transport
 Fructose – absorbed somewhat more slowly-by facilitated
diffusion The single sugar in absorptive cells are then
transferred to portal circulation  to liver.
 The liver then metabolize those sugars by transforming
monosaccharides galactose and fructose into glucose.
26

27. Reading assignment
? LACTOSE MALDIGESTION
AND INTOLERANCE
27

28. Glycemic index
 Not all complex carbohydrates are digested at the same rate;
Some carbohydrate sources lead to immediate rise in blood
Glucose levels after ingestion whereas others slowly raise
blood Glucose levels over an extended period after ingestion.
 Glycemic index of a food is an indication of how rapidly
blood Glucose levels rise after consumption
 The glycemic response to ingested foods depends: not only on
the glycemic index of the foods, but also on:
The fiber content of the food. 28

29. Carbohydrate metabolism
 Carbohydrate metabolism denotes the various biochemical
processes responsible for the formation, breakdown and
interconversion of carbohydrates in living organisms.
 Glucose is the most important carbohydrate as it is
metabolized by nearly all organisms.
 There are three ways in which the tissues dispose blood
glucose:
 It may be utilized directly as a source of energy
 It may be stored in the form of glycogen
 If there is surplus of glucose, it will be converted into fats and
deposited as fats in the body.
29

30. Carbohydrate metabolism…
 The two hormones which control the metabolisms of
carbohydrates in the human body are insulin and glucagon.
 Insulin is secreted by the beta cells of the islets of
Langerhans. Its secretion is stimulated by hyperglycemia
and parasympathetic nervous activity.
 Functions of insulin include:
 To facilitate glucose transport to the liver and muscle cells
 To facilitate formation of glycogen in the liver and muscle
cells
30

31. Carbohydrate metabolism…
 Glucagon is secreted by the alpha cells of the islet of
Langerhans and the secretion is stimulated by
hypoglycemia and sympathetic nervous activity
 Its function is to facilitate the breakdown of glycogen in
the liver and muscle cells into glucose.
31

32. Carbohydrate metabolism…
32

33. Functions of Carbohydrates
 Provide energy (4kcal/g)
 Prevent ketosis
 Sparing protein
 Supply carbon for synthesize of other compounds
 Promote growth of certain desirable bacteria in the intestine
 Needed for the regulation of body processes
 Insoluble fiber makes elimination of waste much easier
 Soluble fiber can reduce blood cholesterol and glucose level 33

34. How much carbohydrate do we need?
34

35. How much fiber do we need?
35

36. Functions of Dietary fibers
 Increasing bulk of intestinal contents  by absorbing
water
 Stimulates peristaltic movements;
 To reduce stool transit time and prevents constipation
 Bind & dilute bile acids
 Lower blood glucose and cholesterol
36

37. Introduction
38

38. Brainstorming
Many People regard fats
and oils as foods which
should be avoided. Do
you agree? Why?
39

39. Lipids
 Lipids are a group of organic chemical compounds that are
insoluble in water but soluble in organic solvents.
 The class of nutrients known as lipids includes triglycerides
(fats and oils), phospholipids, and sterols.
 The most obvious lipids are fats and oils
40

40. Classification of Lipids
 Lipids are classified into three on the basis of their chemical
structure.
1. Simple lipids  Fats and oils (Triglycerides)
 95% of dietary lipids (fats & oils)
2. Compound lipids  Phospho-lipids, Lipoproteins and
Glycolipids.
3. Derived lipids  Fatty acids and sterols
41

41. Fats and oils (Triglycerides)
 Triglycerides are lipids with
three fatty acids attached to a
glycerol.
 They are primary form of lipid.
 Fatty acids are found in the
Triglycerides.
42

42. Fatty acids
 Fatty acids are the simplest form of
lipids found in the Triglycerides. .
 They are long chains of carbons
bonded together and flanked by
hydrogens.
 At one end of the molecule ( alpha end)
is an acidic group and at other end
(the omega end) is a methyl group.
43

43. Classification of Fatty Acids
 Based on number of carbon atom
Short chain (2~4C),
Medium chain (6~10C) &
Long chain(12~26C) fatty acid
 According to whether it contains double bond or not
 Saturated – No carbon to carbon double bond
 Unsaturated fatty acid - Carbon to carbon double bond
 According to weather the body synthesize or not
 Essential
 Non- Essential
44

44. Saturated fatty acid
 All short/medium chain fatty acids
 Long Chain FA are either saturated or
unsaturated
 The major Saturated FA in diet -
palmitic & stearic acids
 Mostly obtained from animal sources
such as butter, dairy product and meat.
 Coconut oil & palm oil – are the only
plant sources of saturated fatty acids. 45

45. Unsaturated fatty acid
 Either they are Monounsaturated:
containing only one double &
polyunsaturated: containing two
or more double bond.
 Most from plant origin
 Most common MUFA in the diet is
oleic acid
 Human breast milk rich in PUFA
acids 46

46. Essential Fatty Acids
 Cannot be synthesized by body
so, we must obtain from the
diet.
 Currently Linoleic (Omega-6
fatty acid) and α-Linolenic
(Omega-3 fatty acid ) acids
are classified as essential acids.
47

47. Essential Fatty Acids…
Functions of FA
 Are needed for the normal functioning of all tissues
 Form a part of the structure of each cell membrane.
 Help transport nutrients and metabolites across the cell
membrane
 Are also involved in brain development
 Are important for immune function and vision
 Are needed for the synthesis of prostaglandin 48

48. Phospholipid
 Phospholipids contain glycerol, two
fatty acids and a phosphate group
with a molecule of choline.
 A well-known phospholipid is lecithin
which is made by liver.
 Food sources of lecithin include eggs,
liver, soybeans, wheat germ and
peanuts
 Roles of Phospholipids- enable
transport of lipids across cell
membranes, emulsifiers.
49

49. Sterols
 A class of lipid with a characteristic
of multi ringed structure.
 A well-known sterol is cholesterol
 Cholesterol serves the precursor of
Vitamin D, bile salt and steroid
hormones also its structural
component of cell membranes
50

50. Sterols
 A class of lipid with a characteristic of
multi ringed structure.
 A well-known sterol is cholesterol
 Cholesterol serves the precursor of
Vitamin D, bile salt and steroid
hormones also its structural
component of cell membranes
51

51. Functions of Lipids
 Are the form of stored energy in animals
 Have high energy value 9 kcal/gm of fat
 Act as carriers for fat soluble vitamins
 Are palatable giving good taste and satiety
 Structural support for cells
 Production of steroid hormones, vitamin D
 EFA important for functions of nervous system
52

52. Food Sources Fats
High Risk for CHD
 Saturated fat (found in foods like meat, butter, and cream) and
(found in baked goods, snack foods, fried foods, and margarines)
Low Risk for CHD
 Unsaturated Fat (PUFAS & MUFAS) (found in foods like
olive oil, avocados, nuts, and canola oil, vegetable oils, fish)
 Replacing saturated and trans fat in your diet with
unsaturated fat has been shown decrease the risk of
developing heart disease.
53

53. Digestion of Lipids
 The first phase of fat digestion begin in mouth and
stomach by the action of salivary and gastric lipase
respectively.
 The main route for digestion of Fats involves:
 Hydrolysis to fatty acids & 2-Monoacylglycerols in
the lumen of the intestine by Pancreatic lipase.
 Globules of fat need to be emulsified before
digestion can take place by bile.
54

54. Absorption, and Transport of Lipids
 Glycerol and short- and medium-chain fatty acids diffuse
and are absorbed directly into the bloodstream.
 Monoglycerides and long-chain fatty acids form micelles,
are absorbed, and are reformed into new triglycerides. With
protein they are transported by chylomicrons.
 Lipid transport is made possible by a group of vehicles
known as lipoproteins.
55

55. Lipoproteins
 These are compound lipids that contain both protein and
various types and amounts of lipids.
 They are 25-30 % proteins and the remaining as lipids.
 They are made mostly in the liver and are used to transport
water-insoluble lipids throughout the body.
56

56. Lipoproteins…
Lipoprotein Primary component Key role
Chylomicron Triglyceride Carries dietary fat from the small
intestine to cells
VLDL Triglyceride Carries lipids made and taken by
up by the liver to cells
LDL Cholesterol Carries cholesterol made by the
liver and from other sources to the
cell
HDL Protein Contribute to cholesterol removal
from cells and in turn excretion of
it from the body
57

57. Lipoproteins…
Health Implications
 High LDL is associated with higher risk of heart attack
and is known as “bad” cholesterol.
 High HDL seems to have a protective effect and is known
as “good” cholesterol.
58

58. Lipoproteins…
Health Implications
 High LDL is associated with higher risk of heart attack
and is known as “bad” cholesterol.
 High HDL seems to have a protective effect and is known
as “good” cholesterol.
59

59. Introduction
60

60. Recommended Intakes of Fat
 The DRI and the 2005
Dietary Guidelines
recommend fat at 20-35% of
energy intake (400-700 kcal
of a 2,000-kcal diet).
 Essential fatty acids Adequate
intake (Table)
62

61. Fat Abnormalities
 The consumption of excess amount of fat will exposed for:-
 Atherosclerosis
 Obesity and
 Metabolic syndrome
63

62. Introduction
65

63. Protein
 Proteins are the main functional and structural building
blocks of every cell in our body.
 Each protein itself is made up of a variety of smaller
components called amino acids.
 Proteins contains C, H, N, O in the form of amino acids, are
essential to cell functions.
 Amino acids -organic acids containing an amino group and
a carboxyl group subunits of proteins
66

64. Protein…
 Proteins are made from 20 different
amino acids, 9 of which are essential.
 Each amino acid has an amino group,
an acid group, a hydrogen atom, and
a side group.
 It is the side group that makes each
amino acid unique.
 The sequence of amino acids in each
protein determines its unique shape
and function. 67

65. Protein…
 There are over 20 amino acids in dietary protein.
 Nine are “essential” amino acids that our bodies cannot
make; we must get these from our diet.
 Dietary proteins from animal sources such as meat, fish and
milk products contain all nine essential amino acids and are
considered complete proteins.
68

66. Protein…
 Eleven amino acids are called “non-essential” because our
bodies are able to make them..
 Most plant sources of protein such as Cereals, nuts and
grains tend to have poor amounts of one or more essential
amino acids and are considered as incomplete proteins.
 A good quality or a complete protein is the one that
supplies all the essential amino acids in sufficient quantities
and in proper ratio for normal growth and maintenance.
69

67. Essential and Non-Essential Amino Acids
70

68. Functions of Protein
 Enzymes- they act as the catalyst
 Provide materials for cell growth and mitosis
 Maintain fluid balance in vasculature (albumins and globulins)
 Maintain blood pH
Form hormones
 Contribute to immune function
 Provide energy - 4 kcal/gram
 To make other compounds
 Transporters
Other Roles
 Blood clotting
 Vision by eye 71

69. Protein Food Sources
 Milk and milk products such as cheese, ice cream all
derive their protein from milk.
 Meat, poultry, and fish are all forms of animal tissues
 Eggs are in a class by themselves a protein food of high
nutritive value.
 Vegetables are poor source of protein.
 Legumes provide more than 4 or 6 percent: they provide
one of the better quality plant proteins. 72

70. Protein Food Sources…
 Legumes listed as meat alternates in the four-food group
charts because they provide one of the better quality plant
proteins.
 Bread and cereals make an important contribution to the
protein of the diet, the protein of uncooked grain ranges 7 to
14 percent.
73

72. Protein Digestion
 The enzymatic digestion of protein begins in the stomach.
 Proteins are first denatured by stomach acid. Then the major
stomach enzyme pepsin breaks polypeptide into shorter
chain of amino acids.
 The partially digested protein move from stomach to into
small intestine along the rest of nutrients and substance in
chyme.
75

73. Protein Digestion…
 Once in Small Intestine, CCK is released which causes
secretion of trypsin, chymotrypsin, carboxypeptidase and
elastase from pancreas.
 These enzymes break up partially digested protein into
polypeptides, dipeptides & amino acid
 Amino-peptidase & di-peptidase secreted by the glands in
the intestinal wall completes the break down of protein into
Amino acid (final products).
76

74. Activation of Peptidases
77

75. Protein Absorption
 In the small intestine short chain amino amino-acids and
individual amino-acids are taken by active transport into
absorptive cells lining small intestine.
 Then amino-acids travel to the liver via portal vein.
 In the liver individual amino-acids can undergo several
modification depending on various body tissues.
 May combined into protein needed by specific cell
 Broken down for energy needs
 Converted into non essential amino acids, glucose or fat.
78

77. Recommended Intakes of Protein
 The recommendations for protein are expressed as grams of
protein per kilogram of body weight per day (g/kg/day).
 Adult Women and Men need 0.8 g/kg/day
 Pregnant and lactating women need 1.1 and 1.3 g/kg/day,
respectively.
Example: for a 70 kg person: 70 kg x 0.8 g/kg = 56 grams of protein
per day
81

78. Protein-energy-malnutrition (PEM)
 PEM is today the most serious nutritional problem in
Ethiopia and other developing countries.
 Its two clinical forms are Kwashiorkor and Marasmus.
 The diseases occur mostly in children between one and
three years of age, after they have been taken of the breast.
82

79. Marasmus
 Marasmus: Severe form of acute malnutrition that is
characterized by wasting of body tissues.
Marasmic children are extremely thin.
 Kwashiorkor: Severe form of acute malnutrition characterized
by bilateral edema and weight-for-height of greater or equal
to -2 SD.
 Marasmic-Kwashiorkor: Severe form of acute malnutrition
characterized by bilateral edema and weight-for-height of
less than -2 SD. 83

80. Introduction
84

81. Introduction
86