1. CARBOHYDRATES
PART-I
BY-
Dr. Shefali Jaiswal
Dept of Public Health
Dentistry 1

2. CONTENTS
• History
• Introduction
• Functions
• Classification – Monosaccharides
Disaccharides
Oligosaccharides
Polysaccharides
• Digestion of carbohydrates
• Absorption of carbohydrates
• Dietary guidelines
2

3. • Carbohydrates and oral health
• Nutritional health programs in India
• Public health significance
• Conclusion
• References
3

4. HISTORY
4

5. • During the Paleolithic era, from approximately 2.5 million
to 10,000 years ago, paleo diet was followed.
• Paleo diet included lean meats, fish, fruits, vegetables, nuts
and seeds — foods that in the past could be obtained by
hunting and gathering.
• With the knowledge of fire and evolution of farming the
ancestral man began the consumption of tuberous roots,
inner barks of trees, nuts etc.
Hardy K, Brand-Miller J, Brown KD, Thomas MG, Copeland L. The importance of dietary carbohydrate in
human evolution. The Quarterly review of biology. 2015 Sep;90(3):251-68. 5

6. • In nutritional terms, the diet of pre-historic man and his
ancestors was rich in proteins, moderately rich in fat, and
usually poor in carbohydrate.
• This means that their diet mostly consisted of sugars and
starch.
Yudkin J. Evolutionary and historical changes in dietary carbohydrates. The American
journal of clinical nutrition. 1967 Feb 1;20(2):108-15.
6

7. INTRODUCTION
7

8. • Carbohydrates are the most abundant of all the organic
compounds in nature.
• Composed of carbon, hydrogen, and oxygen.
• The word Carbohydrate means ‘hydrates of carbon’.
• Defined as polyhydroxy-aldehydes or ketones or
compounds which produce them on hydrolysis.
8

9. FUNCTIONS
• They are the most abundant dietary source of energy for
all organisms. (4 Cal/g)
• Intermediates in the biosynthesis of other basic
biochemical entities. (fats and proteins)
• Associated with other entities such as glycosides, vitamins
and antibiotics.
• Forms structural tissues in plants and in microorganisms.
(cellulose, lignin, murein)
9

10. • Participates in biological transport, cell-cell recognition,
activation of growth factors, modulation of the immune
system.
10

11. 11
CLASSIFICATION OF CARBOHYDRATES
• Trioses, Tetroses, Pentoses, HexosesMonosaccharides
(monoses or
glycoses)
• Di, tri, tetra, penta, up to 9 or 10
• Most important are the disaccharides
Oligosaccharides
• a)Homopolysaccharides
• b) Heteropolysaccharides
Polysaccharides
or glycans

12. MONOSACCHARIDES
• Monosaccharides are simple sugars, or the compounds
which possess a free aldehyde (CHO) or ketone (C=O)
group and two or more hydroxyl (OH) groups.
• They are the simplest sugars and cannot be hydrolysed
further into smaller units.
• Monosaccharides contain a single carbon chain and are
classified on the basis of number of carbon atoms they
possess, and as aldoses or ketoses depending upon their
groups.
12

13. PROPERTIES
• Mutarotation : when a monosaccharide is dissolved in
water, the optical rotatory power of the solution gradually
changes until it reaches a constant value.
• For ex : when D-glucose is dissolved in water, a specific
rotation of +112.2° is obtained, but this slowly changes , so
that at 24h the value becomes +52.7°.
• This gradual change in specific rotation is known as
mutarotation. This phenomenon is shown by number of
pentoses, hexoses and reducing disaccharides.
13

14. • Glucoside formation : when D-glucose solution is treated
with methanol and HCl, two compounds are formed, these
are α – and β-D- glucosides.
• Thus, formed glucosides are not reducing sugar and also
doesnot show phenomenon of mutarotation.
14

15. • Reducing power : Sugars having free or potentially free
aldehyde or ketone group have an ability to reduce the
cupric copper to cuprous .
Reducing sugar + 2 Cu++ oxidized + 2Cu+
(cupric) sugar (cuprous)
15

16. • Oxidation / Reduction: The alcoholic OH, aldehyde (COH)
or keto (C=O) group are oxidized to carboxyl group with
certain oxidizing agents.
• The oxidation may be brought under mild or with vigorous
oxidizing condition
i. With mild oxidant like BrH2O : In this group only
aldehyde is oxidized to produce gluconic acid
(monocarbonic). Ketoses do not respond to this reaction.
16

17. ii. With strong Oxidizing agent like Conc HNO3 : Both
aldehyde or ketone groups are oxidized to yield
dicarboxylic acids.
iii. Oxidation with metal hydroxides: Metal hydroxides
like Cu(OH)2, Ag OH oxidize free aldehyde or ketone group
of mutarotating sugar and reduce themselves to lower
oxides of free metals.
17

18. • Reduction: The aldehyde or ketone group present can be
reduced to its respective alcohol with sodium amalgum.
For ex: Fructose and glucose give the hexahydric alcohol
i.e. Sorbitol and Mannitol.
18

19. • Dehydration : The monosaccharides when treated with
Conc H2SO4, it gets dehydrated to from
5 – hydroxyl – methyl furfural derivative
• Methylation or Esterification : The glucosidic and
alcoholic OH group of monosaccharides and reducing
disaccharides react with acetylating agent like acetic
anhydride in pyridine to form acetate derivatives called
esters.
19

20. IMPORTANT DERIVATIVES OF
MONOSACCHARIDES
20

21. AMINO SUGARS
• They are formed by replacing the hydroxyl group (at C2
usually) of monosaccharides by amino group.
• The most common amino sugars are glucosamine and
galactosamine.
-Glucosamine is present in Heparin, Hyaluronic acid and
blood group substances.
-Galactosamine is present in Chondroitin of cartilages and
tendons.
21

22. • The amino group may be condensed with active acetate
forming N-acetyl glucosamine.
• They are components of glycosaminoglycans and some
glycosphingolipids (lipids).
N-acetyl Mannosamine - it is a component of glycoproteins
and gangliosides(Lipids) of cell membrane.
A polymer of N-Acetyl Glucosamine is a component of chitin
N-Acetyl Galactosamine is a component of Chondroitin
sulphate.
22

23. AMINO SUGAR ACIDS
• Amino sugar acids are produced by condensation of amino
sugar with Pyruvic or lactic acid.
• e.g.Muramic acid is produced by the condensation of lactic
acid with D- Glucosamine. Certain bacterial cell walls
contains muramic acid.
• N-Acetyl Neuraminic acid is formed from the condensation
of Pyruvic acid with N-Acetyl Mannosamine.
23

24. DEOXY SUGARS
• They are formed by removal of an oxygen atom usually
from 2nd carbon atom.
• One quite ubiquitous deoxy sugar is 2’-deoxy ribose which
is the sugar found in DNA.
• 6-deoxy-l-mannose (l-rhamnose) is used as a fermentative
reagent in bacteriology
24

25. SUGAR ACIDS
• Sugar acids are formed by the oxidation of aldehyde
C1(Aldonic acid) or terminal hydroxyl group at C6 of
aldose sugar(uronic acid) or both (saccharic) to form
carboxylic group.
• Glucuronic and Iduronic acids are the components of
glycosaminoglycans.
• L-ascorbic acid(vitamin C) is a sugar acid.
• Glucuronic acid is involved in detoxification of bilirubin
and other foreign compounds.
25

26. SUGAR ALCOHOLS
• Are formed by the reduction of the carbonyl group
(aldehyde or ketone ) of monosaccharide
26

27. SUGAR ESTERS
• Hydroxyl groups of sugars can be esterified to form
Acetates, phosphates, benzoates etc.
• Sugars are phosphorylated at terminal C1 hydroxyl
group or at other places .
At terminal hydroxyl: Glucose-6-P or ribose-5-P.
At C1 hydroxyl group: Glucose-1-P.
At both places: Fructose 2,6 bisphosphate
• Metabolism of sugars inside the cells starts with
phosphorylation.Sugar phosphates are also components of
nucleosides and nucleotides. 27

28. GLYCOSIDES
• Acetal derivatives formed when a monosaccharide reacts
with an alcohol in the presence of an acid catalyst are
called glycosides.
• In naming of glycosides, the "ose" suffix of the sugar name
is replaced by "oside", and the alcohol group name is
placed first.
28

29. • As is generally true for most acetals, glycoside formation
involves the loss of an equivalent of water.
• The diether product is stable to base and alkaline oxidants
such as Tollen's reagent.
• Since acid-catalyzed aldolization is reversible, glycosides
may be hydrolyzed back to their alcohol and sugar
components by aqueous acid
29

30. • The anomeric methyl glucosides are formed in an
equilibrium ratio of 66% alpha to 34% beta.
• Pyranose rings prefer chair conformations in which the
largest number of substituents are equatorial.
• In the case of glucose, the substituents on the beta-anomer
are all equatorial, whereas the C-1 substituent in the alpha-
anomer changes to axial.
30

31. • Since substituents on cyclohexane rings prefer an
equatorial location over axial (methoxycyclohexane is 75%
equatorial), the preference for alpha-glycopyranoside
formation is unexpected, and is referred to as the anomeric
effect.
31

32. 32

33. • Glycosides abound in biological systems. By attaching a
sugar moiety to a lipid or benzenoid structure, the
solubility and other properties of the compound may be
changed substantially.
• Because of the important modifying influence of such
derivatization, numerous enzyme systems, known as
glycosidases, have evolved for the attachment and removal
of sugars from alcohols, phenols and amines. Chemists
refer to the sugar component of natural glycosides as
the glycon and the alcohol component as the aglycon.
33

34. SIGNIFICANCE OF GLYCOSIDES
1) Cardiac Glycosides - These include derivatives of
digitalis and strophanthus such as oubain.
2)Streptomycin is used as an antibiotic.
3) Phloridzine - displaces Na+ from the binding site of
“carrier protein” and prevents the binding of sugar
molecule and produces Glycosuria.
34

35. • Carbohydrates with free carbonyl groups or in hemiacetal
form give positive tests to Benedict’s and Fehling’s
reagents without having been hydrolyzed are referred as
‘reducing’ sugars ; others (i.e., the acetal types) are then
‘non-reducing’ sugars
35

36. STERIOCHEMISTRY
• Optical isomers (= enantiomers) differ from each other in
the disposition of the various atoms or groups of atoms in
space around the asymmetric carbon atom.
• These are, in fact, the mirror image of each other.
• These may also be likened to left- and right-handed gloves.
36

37. • One form in which H atom at carbon 2 is projected to the
left side and OH group to the right is designated as D-form
and the other form where H atom is projected to the right
side and OH group to the left is called as L-form
• For example, the glyceraldehyde has only one asymmetric
carbon atom (numbered as 2) and it can, therefore, exist in
2 isomeric forms :
37

38. STRUCTURAL ASPECT
• Saccharide structures differ only in the orientation of the
hydroxyl groups (-OH).
• This slight structural difference makes a big difference in
the biochemical properties, organoleptic properties (e.g.,
taste), and in the physical properties such as melting point
and Specific Rotation.
38

39. • A chain-form monosaccharide that has a carbonyl group
(C=O) on an end carbon forming an aldehyde group (-CHO)
is classified as an aldose.
• When the carbonyl group is on an inner atom forming a
ketone, it is classified as a ketose.
39

40. 40

41. CONDENSATION REACTIONS: ACETAL
AND KETAL FORMATION
41

42. 42

43. 43

44. DISACCHARIDES
• The disaccharides are sugars composed of two
monosaccharide residues linked by a glycosidic bond.
• The disaccharides of physiological importance are as
follows-
1)Maltose
2)isomaltose
3)Sucrose
4)Lactose
5)Lactulose
6) Trehalose
44

45. MALTOSE (Malt sugar)
• Maltose is formed by joining of 2 glucose units by α-(1,4)
glycosidic bond.
45

46. • Produced by partial hydrolysis of starch either by Salivary
or Pancreatic amylase.
• Has a free active group and hence exhibits reducing
properties, mutarotation and - isomerism.
Uses-
• Fermentable sugar.
• Used as a nutrient (malt extract; Hordeum vulgare); as a
sweetener and as a fermentative reagent
46

47. ISO MALTOSE
47
• Composed of two glucose units linked by α -1,6 glycosidic
linkage.
O- α -D-glucopyranosyl-(1-6)- α -D-glucopyranose
• It is produced by enzymatic hydrolysis of starch (at the
branch point in Amylopectin).

48. SUCROSE (TABLE SUGAR)
• Commercially obtained from sugar cane, Beet root, fruits
and vegetables.
• O-α-D-glucopyranosyl-(1-2)-β-D-fructofuranoside
• The anomeric carbon atoms of a glucose unit and a
fructose unit are joined in this disaccharide; the
configuration of the glycosidic linkage is α for glucose and
β for fructose.
48

49. • Sucrose has no free reactive group because the anomeric
carbons of both monosaccharides units are involved in the
glycosidic bond.
• Thus, sucrose neither shows reducing properties nor
mutarotation characters.
• Hydrolytic product of Sucroseis called invert sugar
because the optical activity of sucrose ( dextrorotatory) is
inverted after hydrolysis [by an acid or an enzyme
(invertase or sucrase)] into equimolar mixture of its two
components glucose (+52.5) and fructose (-92.5) and the
optical activity of the mixture becomes levorotatory. 49

50. 50
• Sucrose can be cleaved into its component monosaccharides
by the enzyme sucrase.
• Sucrase, lactase, and maltase are located on the outer
surfaces of epithelial cells lining the small intestine.
• Rare genetic lack of sucrase leads to sucrose intolerance —
diarrhea and flatulence

51. LACTOSE (MILK SUGAR)
• b-D-galactose joined to b -D-glucose via b (1,4) linage
O-β-D-galactopyranosyl-(1-4)- β –glucopyranose.
51

52. • Lactose is the only sugar of milk -
Synthesized by mammary glands during lactation.
Milk contains the α and β-anomers in a 2:3 ratio.
β -lactose is sweeter and more soluble than ordinary
α – lactose.
used in infant formulations, medium for penicillin
production and as a diluent in pharmaceuticals.
52

53. • Lactose is hydrolyzed to its monosaccharide components
by lactase enzyme in human beings and by β galactosidase
in bacteria.
• Deficiency of lactase causes Lactose intolerance,
manifested by diarrhea, abdominal cramps, bloating and
distension.
53

54. TREHALOSE
O-α-D-glucopyranosyl-(1-1)-α-D-glucopyranoside
• Found in Yeasts and fungi; the main sugar of insect
hemolymph .
• Non reducing in nature due to lack of free functional group
54

55. OLIGOSACCHARIDES
• Trisaccharide: Raffinose (glucose + galactose + fructose)
• Tetrasaccharide: Stachyose (2 galactose + glucose +
fructose)
• Pentasaccharide: Verbascose (3 galactose + glucose +
fructose)
• Hexasaccharide: Ajugose (4 galactose + glucose + fructose)
55

56. POLYSACCHARIDES OR GLYCANS
1) Homoglycans (Starch, Cellulose, Glycogen, Dextrins or
Inulin)
2) Heteroglycans (Mucopolysaccharides)
Characteristics:
-polymers (MW from 200,000)
-White and amorphous products (glassy)
-not sweet
-not reducing; do not give the typical aldose or ketose
reactions
-form colloidal solutions or suspensions
56

57. • Homopoysaccharides are polymers composed of a single type of
sugar monomers
HOMOPOYSACCHARIDES
57
Homo
polysaccharides
Glucosans
e.g. Starch,
Glycogen,
Cellulose
Fructosan
e.g. Inulin
Galactosan
e.g. Agar

58. 1) GLUCOSANS /GLUCANS
Glycogen (Storage Polysaccharide) –
• Also known as animal starch.
• Stored in muscle and liver.
• Present in cells as granules (high MW).
• Contains both α (1,4) links and α (1,6) branches at every 8
to 12 glucose unit.
• Complete hydrolysis yields glucose.
• With iodine gives a red-violet color.
• Hydrolyzed by both α and β-amylases by glycogen
phosphorylase.
58

59. GLYCOGEN
• In the liver, glycogen synthesis and degradation are
regulated to maintain blood-glucose levels as required to
meet the needs of the organism as a whole.Glycogen serves
as a buffer to maintain blood glucose level.
• In muscle, these processes are regulated to meet the
energy needs of the muscle itself.
• The concentration of glycogen is higher in the liver than in
muscle (10% versus 2% by weight), but more glycogen is
stored in skeletal muscle overall because of its much
greater mass.
59

60. 2) STARCH (STORAGE
POLYSACCHARIDE)
• Most common storage polysaccharide in plants.
• Composed of 10 – 30% Amylose and 70-90% amylopectin
depending on the source –
(a) Amylose is a linear polymer of α-D-glucose, linked
together by α -1→4 glycosidic linkages.
It is soluble in water, reacts with iodine to give a blue color
and the molecular weight of Amylose ranges between
50, 000 – 200, 000.
60

61. (b) Amylopectin is a highly branched polymer, insoluble in
water, reacts with iodine to give a reddish violet color.
The molecular weight ranges between 70, 000 - 1 000, 000.
Branches are composed of 25-30 glucose units linked by
α-1→4 glycosidic linkage in the chain and by α-1→6
glycosidic linkage at the branch point.
61

62. • Suspensions of Amylose in
water adopt a helical
conformation
• Iodine (I2) can insert in the
middle of the Amylose
helix to give a blue color
that is characteristic and
diagnostic for starch
62

63. 3) DEXTRINS
• Produced by the partial hydrolysis of starch along with
maltose and glucose.
• Dextrins are often referred to as either amylodextrins,
erythrodextrins or achrodextrins.
• Used as mucilages (glues).
• Used in infant formulas (prevent the curdling of milk in
baby’s stomach).
63

64. • Indigestible dextrin are developed as soluble fiber
supplements for food products.
• Also Used as thickening agents in food processing.
64

65. 4) DEXTRANS
• Products of the reaction of glucose and the enzyme
Transglucosidase from Leuconostoc mesenteroides.
• Contains α (1,4), α(1,6) and α (1,3) linkages with molecular
weight : 40,000; 70,000; 75,000.
• Used as plasma expanders (treatment of shock).
• also used as molecular sieves to separate proteins and
other large molecules (gel filtration chromatography).
• Also as Component of dental plaque. 65

66. 5) CELLULOSE (STRUCTURAL
POLYSACCHARIDE)
• Polymer of β-D-glucose linked by β(1,4) linkages.
• Yields glucose upon complete hydrolysis.
• Partial hydrolysis yields cellobiose.
• Most abundant of all carbohydrates.
• Gives no color with iodine.
• Cellulose is tasteless, odorless and insoluble in water and
most organic solvents. 66

67. • Cellulose consists of β-D-glucopyranose units linked by
β 1 →4 bonds to form long, straight chains strengthened by
cross-linking hydrogen bonds.
67

68. CELLULOSE- DIGESTION
• Mammals lack any enzyme that hydrolyzes the β 1→ 4
bonds, and so cannot digest cellulose.
• It is an important source of "bulk" in the diet, and the
major component of dietary fiber.
• Microorganisms in the gut of ruminants and other
herbivores can hydrolyze the linkage and ferment the
products to short-chain fatty acids as a major energy
source.
68

69. SIGNIFICANCE OF CELLULOSE
• Microcrystalline cellulose : used as binder - disintegrant in
tablets.
• Methylcellulose: suspending agent and bulk laxative.
• Oxidized cellulose: hemostat.
• Sodium carboxymethyl cellulose: laxative.
• Cellulose acetate: rayon; photographic film; plastics.
69

70. • Cellulose acetate phthalate: enteric coating.
• Nitrocellulose: explosives; collodion (pyroxylin)
70

71. CHITIN - STRUCTURAL
POLYSACCHARIDE
• Chitin is the second most abundant carbohydrate polymer
of N- Acetyl Glucosamine.
• present in the cell wall of fungi and in the exoskeletons of
crustaceans, insects and spiders.
• chitin is used commercially in coatings (extends the shelf
life of fruits and meats)
71

72. INULIN (FRUCTOSAN) STORAGE
POLYSACCHARIDE
• β-(1,2) linked fructofuranoses.
• Linear, no branching. Lower molecular weight than starch.
Colors yellow with iodine.
• On Hydrolysis yields fructose.
• Sources include onions, garlic, dandelions and Jerusalem
artichokes.
72

73. USES OF INULIN
• Used as diagnostic agent for the evaluation of glomerular
filtration rate (renal function test).
• Used as a soluble dietary fiber.
• Used as appetite suppressant.
• Used as a low glycemic index sweetener.
• Also used as a fat/cream substitute.
73

74. HETEROPOLYSACCHARIDES/
MUCOPOLYSACCHARIDES
• Mucopolysaccharides or Glycosaminoglycans are
carbohydrates containing a repeating disaccharide.
• The disaccharide usually contains an acid sugar and an
amino sugar.
• Acid sugar is generally D- Glucuronic acid or its C-5
epimer Iduronic acid, while amino sugar is either D-
Glucosamine or D-Galactosamine, amino group is generally
acetylated eliminating its positive charge.
74

75. • The amino sugar may be sulfated on non-acetylated
nitrogen.
• Carboxyl groups of acid sugars together with sulfate
groups give Glycosaminoglycans strongly negative nature.
75

76. PHYSIOLOGICAL SIGNIFICANCE OF
GLYCOSAMINOGLYCANS
Hyaluronic acid-(D-glucuronate + GlcNAc)n
• Occurrence: synovial fluid, ECM of loose connective tissue.
Serves as a lubricant and shock absorber.
• Hyaluronic acid does not contain any sulfate and is not
found covalently attached to proteins.
• It forms non-covalently linked complexes with
Proteoglycans in the ECM.
• Hyaluronic acid polymers are very large (100 - 10,000
kDa) and can displace a large volume of water. 76

77. • Dermatan sulfate
Occurrence: skin, blood vessels, heart valves.
• Chondroitin sulfate
Occurrence: cartilage, tendons, ligaments, heart valves and
aorta.
It is the most abundant
glycosaminoglycan(GAG).
77

78. Heparin (D-glucuronate sulfate + N-sulfo-D-glucosamine) n
• Heparans have less sulfate groups than heparins.
• Occurrence: component of intracellular granules of mast
cells lining the arteries of the lungs, liver and skin
( Contrary to other GAGs that are extra cellular
compounds, it is intracellular). Acts as an anticoagulant.
• Heparan sulfate : basement membranes, component of cell
surfaces
78

79. Keratan sulfate (Gal + GlcNAc sulfate) n
Occurrence: cornea, bone, cartilage; Keratan sulfates are
often aggregated with Chondroitin sulfates.
79

80. DIGESTION OF CARBOHYDRATES
80

81. 2 Types of enzymes are important for the digestion
of carbohydrates
Amylases Disaccharidases
Salivary
Amylase
Pancreatic
Amylase
convert polysaccharides to
disaccharides
Convert disaccharides to
monosaccharides which
are finally absorbed
Maltase
Sucrase-
Isomaltase
Lactase
Trehalase
81

82. 82
Digestion in
mouth
Digestion
in stomach
Digestion
in small
intestine

83. •Digestion of Carbohydrate starts in the mouth, upon
contact with saliva during mastication.
Saliva contains a carbohydrate splitting enzyme called
salivary amylase , also known as ptylin.
DIGESTION IN THE MOUTH
83

84. ACTION OF PTYLIN (SALIVARY
AMYLASE)
• It is α-amylase and requires Cl− ion for activation with an
optimum pH of 6.7 (Range 6.6 to 6.8).
• The enzyme hydrolyses α-1→ 4 glycosidic linkages deep
inside polysaccharide molecules.
• However, ptylin action stops in the stomach when the pH
falls to 3.0.
84

85. Starch, Glycogen and dextrins
(Large polysaccharide molecules)
α- Amylase
Glucose, Maltose and Maltotriose.
(Smaller molecules)
85

86. • There is no enzyme to break the glycosidic bonds in gastric
juice.
• However, HCl present in the stomach causes hydrolysis of
sucrose to fructose and glucose.
Sucrose Fructose + Glucose
HCl
DIGESTION IN THE STOMACH
86

87. • It is an α- Amylase.
• Optimum pH=7.1
• Like ptylin, it requires Cl− ion for its activity.
• It hydrolyses α-1→ 4 glycosidic linkages situated well inside
polysaccharide molecules.
Note: Pancreatic amylase, an isoenzyme of salivary amylase,
differs only in the optimum pH of action. Both the enzymes
require Chloride ions for their actions (Ion activated
enzymes).
ACTION OF PANCREATIC
AMYLASE
87

88. Starch/Glycogen
Maltose/ Isomaltose
+
Dextrins and
oligosaccharides
Pancreatic
Amylase
88

89. • Main digestion takes place in the small intestine by
pancreatic amylase.
• Digestion is completed by pancreatic amylase because food
stays for a longer time in the intestine.
DIGESTION IN SMALL INTESTINE
89

90. REACTIONS CATALYZED BY
DISACCHARIDASES
• Maltose Glucose + Glucose
• Sucrose Isomaltose 3Glucose + fructose
• Lactose Glucose +
Galactose
90
Maltase
Sucrase, Isomaltase
Lactase

91. CLINICAL SIGNIFICANCE OF
DIGESTION
• Lactose intolerance is the inability to digest lactose due to
the deficiency of Lactase enzyme.
Causes
91
Congenital Acquired during lifetime
Primary Secondary

92. • It is a congenital disorder.
• There is complete absence or deficiency of lactase enzyme.
• The child develops intolerance to lactose immediately after
birth.
• It is diagnosed in early infancy.
• Milk feed precipitates symptoms.
CONGENITAL LACTOSE
INTOLERANCE
92

93. BABY WITH LACTOSE
INTOLERANCE
93

94. • Primary lactase deficiency develops over time.
• There is no congenital absence of lactase but the deficiency
is precipitated during adulthood.
• The gene for lactose is normally expressed upto RNA level
but it is not translated to form enzyme.
• It is very common in Asian population.
• There is intolerance to milk + dairy products.
PRIMARY LACTASE DEFICIENCY
94

95. ADULT WITH LACTOSE
INTOLERANCE
95

96. • Avoidance of dairy products.
• Although the body’s ability to produce lactase cannot be
changed, the symptoms of lactose intolerance can be
managed with dietary changes.
• Most people with lactose intolerance can tolerate some
amount of lactose in their diet. Gradually introducing small
amounts of milk or milk products may help some people
adapt to them with fewer symptoms.
• Partly digested dairy products can also be given.
96
MANAGEMENT

97. • Lactose-free, lactose-reduced milk, Soy milk and other
products may be recommended. Lactase enzyme drops or
tablets(Yeast tablets) can also be consumed.
• Getting enough calcium is important for people with lactose
intolerance when the intake of milk and milk products is
limited.
• A balanced diet that provides an adequate amount of
nutrients—including calcium and vitamin D—and minimizes
discomfort is to be planned for the patients of lactose
intolerance.
97

98. SUCRASE-ISOMALTASE
DEFICIENCY
• These 2 enzymes are synthesized on a single polypeptide
chain, hence , their deficiencies coexist.
• Signs and symptoms are same as that of lactose
intolerance.
• Urine does not give +ve test with Benedict’s test because of
sucrose(Non reducing sugar).
• History confirms the diagnosis. Most confirmatory test is
mucosal biopsy.
98

99. 3 mechanisms
Passive
diffusion
Facilitated
diffusion/Carrier
mediated
Active
transport
ABSORPTION OF CARBOHYDRATES
99

100. Features Passive diffusion Facilitated
diffusion
Active transport
Concentration
gradient
Down the
concentration
gradient from high to
low.
Down the
concentration
gradient from high to
low.
Against a
concentration
gradient from low to
high
Energy
expenditure
none none Energy expenditure
is in the form of ATP
Carrier protein/
transporter
Not required required required
Speed Slowest mode Fast Fastest mode
Note: Glucose is a polar molecule. It cannot pass through lipid
bilayer of cell.
100

101. Glucose transporters
Na+
dependent
transporter
Na+
independent
transporter
2 types
SGLT
GLUT
Also called
Also called
GLUCOSE TRANSPORTERS
101

102. 102

103. 3 REASONS FOR EXPULSION OF
SODIUM
1) Na + is osmotically active, causes osmotic flow to cells,
leading to osmolysis.
2) Na+ concentration has to be kept minimal to maintain the
downward gradient.
3) Na + is inhibitory to many enzyme actions.
103

104. CLINICAL SIGNIFICANCE
• In deficiency of SGLT- 1, glucose is left unabsorbed and is
excreted in feces. Galactose is also malabsorbed.
• In deficiency of SGLT- 2, the filtered glucose is not
reabsorbed back, it is lost in urine, causing glycosuria.
104

105. • Solvent drag is not the main mechanism of glucose
absorption but is important after a carbohydrate rich diet.
• Absorption of galactose is faster than glucose.
• In kidney, reabsorption of filtered glucose takes place by a
similar mechanism, i.e, it is also a co-transport with Na. The
transporter is SGLT- 2.
• In intestine, it is SGLT- 1.
105

106. ABSORPTION OF
MONOSACCHARIDES
106

107. • The absorption is faster through intact mucosa.
• The absorption is decreased if there is some inflammation or
injury to the mucosa.
• Thyroid hormones ↑ the rate of absorption of glucose.
• Mineralocorticoid,i.e Aldosterone ↑ the rate of absorption.
FACTORS AFFECTING RATE OF
ABSORPTION OF MONOSACCHARIDES
107

108. • Vitamin B6, B12, pantothenic acid, folic acid are required
for absorption of glucose.
• With advancing age, rate of absorption declines.
• Note: Insulin has no role in the absorption of
monosaccharide like glucose.
108

109. • Mechanism: facilitated diffusion.
• There are 7 important glucose transporter for uptake of
glucose into special cells.
• They have been numbered from 1 to 7 (GLUT 1 to GLUT 7).
• They are biologically important.
UPTAKE OF GLUCOSE IN PERIPHERAL CELLS
109

110. Tissue specific
glucose
transporter
Tissue distribution Functions Clinical
significance
GLUT-1
(great affinity for
glucose)
Present in almost all
cells with an
abundance in RBC.
Na-independent Cancer cells
express high level of
GLUT-1, so they can
internalize more of
glucose, which is
used as a source of
energy for rapidly
dividing cells.
GLUT-2
(low affinity for
glucose, it can
transport only when
there is glucose load
in the body)
Present in intestine,
liver and pancreas.
Releases insulin by
movement of
glucose into β-cells
of pancreas.
(Acts as a sensor for
the release of insulin
by pancreas.)
Promotes uptake of
glucose in liver cells,
lowering down blood
glucose.
Diabetes Mellitus.
110

111. GLUT 3 Brain cells, all
other cells of body
Cancer cells
express high level
of GLUT-3, so they
can internalize
more of glucose,
which is used as a
source of energy
for rapidly dividing
cells
GLUT 4 Adipose tissue,
skeletal muscles,
cardiac muscles
The only
transporters which
are under the
influence of insulin.
Insulin promotes
uptake of glucose in
the tissues by
mobilizing the
transporters to the
cell surface
whenever there is
high glucose
concentration in the
blood.
111

112. Oral manifestations
112

113. DIETARY GUIDELINES
113

114. • Carbohydrates are major sources of energy in all human
diets.
• They provide energy of 4 Kcal/g.
• In India, 70-80% of total dietary calories are derived from
carbohydrates present in plant foods such as cereals,
millets and pulses.
114

115. A healthy diet of carbohydrates should include-
• Energy intake (calories) should balance energy
expenditure. Total fat should not exceed 30% of total
energy intake to avoid unhealthy weight gain.
• Unsaturated fats (e.g. found in fish, avocado, nuts,
sunflower, canola and olive oils) are preferable to
saturated fats (e.g. found in fatty meat, butter, palm and
coconut oil, cream, cheese, ghee and lard).
115

116. • Limiting intake of free sugars (sugar-sweetened beverages,
sugary snacks and candies) to less than 10% of total
energy.
• At least 400 gm of fruit and vegetables must be included
every day in diet. They should be eaten raw and fresh
preferably.
116

117. BALANCED DIET?
• A balanced diet is one which provides all the nutrients in
required amounts and proper proportions.
• It can easily be achieved through a blend of the four basic
food groups. (fruits, legumes, whole grains and vegetables)
• The quantities of foods needed to meet the nutrient
requirements vary with age, gender, physiological status
and physical activity.
117

118. • A balanced diet should provide around 50-60% of total
calories from carbohydrates, preferably from complex
carbohydrates, about 10-15% from proteins and 20-30%
from both visible and invisible fat.
118

119. 119

120. 120

121. 121

122. 122

123. GLYCAEMIC INDEX
• It is defined by the area under the two-hour blood glucose
response curve following the ingestion of a fixed portion of
test carbohydrate as a proportion (%) of the AUC of the
standard.
• Some foods containing different fractions of soluble and
insoluble fibres favour slow release of sugar into small
intestine and its absorption into blood.
• Used in management of diabetes and control of obesity.
123

124. 124

125. CARBOHYDRATES AND ORAL HEALTH
125

126. DIETARY STUDIES
Hopewood study in Australia –
• A 15-year study (1948 - 1963) done at a children's home
(Hopewood House) in Bowral, New South Wales, Australia.
• The study was done to determine if the significantly
different diet of the children living at the home (as
compared to that of the children in the average Australian
family household) would affect dental caries activity.
• At the start of the study, 78% of the children were caries-
free, and 53% continued to be caries-free at age 13.
126

127. • This was significantly higher than the proportion of caries-
free 13-year-olds within the general residential
population—only 0.4%.
• When the children from Hopewood House were relocated
as they became older, they no longer adhered to their strict
diet.
• The result was a steep increase in caries increment,
similar to that found in other children, indicating that teeth
do not acquire any permanent resistance to dental caries.
127

128. 128
Vipeholm study in Sweden –
• Conducted from 1945 - 1953 at the Vipeholm Hospital,
Sweden, an institute for the mentally-deficient.
• The aim of the Vipeholm Study (Gustaffson, et al.1954) was
to determine the relationship between diet, frequency of
sugar intake and dental caries.
• The variables included the type of sugar ingested (sticky or
non-sticky form) and the frequency of sugar intake (at
meals or in between meals).

129. • The subjects (436 patients) were split into one control
group and six main test groups, where the 'bread' and '24-
toffee' groups were further divided into two separate
groups according to gender.
Conclusions -
• There is a positive correlation between consumption of
sugar (between meals and at meals) and caries increment.
• Sugar consumption in between meals has a larger effect on
increasing dental caries activity than sugar consumption
during meals, even if sugar is taken up to four times a day
at meals.
129

130. Turku study –
• The purpose was to study differences in the caries
increment rate as influenced by various sugars.
• The trial involved almost complete substitution of sucrose
(S) by fructose (F) or xylitol (X) during a period of 2 years.
• There were no significant initial differences as to caries
status between the prospective sugar groups; 35 subjects
in the S-group, 38 in the F-group, and 52 in the X-group.
130

131. • The results showed a massive reduction of the caries
increment in relation to xylitol consumption.
• Fructose was found to be less cariogenic than sucrose.
• It was suggested that the non- and anticariogenic
properties of xylitol principally depend on its lack of
suitability for microbial metabolism and physico-chemical
effects in plaque and saliva.
131

132. Stephans curve –
• The pH of dental plaque under resting conditions (i.e.,
when no food or drink has been consumed), is fairly
constant.
• The response after exposure of dental plaque to a
fermentable carbohydrate is that pH decreases rapidly,
reaching a minimum in approximately 5 to 20
minutes. This is followed by a gradual recovery to its
starting value, usually over 30 to 60 minutes.
132

133. • Food residues, specifically carbohydrates, have caries
promoting characteristics that allow fermentation and acid
accumulation to occur in bacterial plaque.**
• It enhances the four activities of biofilm: implantation,
colonization, metabolic activity and thickness. When
carbohydrates are restricted in a diet, it limits an essential
factor for the development of caries.
**Walsh LJ. Dental plaque fermentation and its role in caries risk assessment. International
Dentistry South Afria (Australasian Edition). 2006;1(3):4-13.
133

134. • The Vipeholm study in 1954* first established the strong
relationship between consumption and dental caries.
• It was supported by the investigation of Sreebny in 1982,**
which described the extensive reviews on the study,
reaffirming its results.
*Gustafsson BE, Quensel CE, Lanke LS, Lundqvist C, Grahnen H, Bonow BE, Krasse BO. The
effect of different levels of carbohydrate intake on caries activity in 436 individuals
observed for five years. Acta Odontologica Scandinavica. 1953 Jan 1;11(3-4):232-364.
**Sreebny LM. Sugar availability, sugar consumption and dental caries. Community
dentistry and oral epidemiology. 1982 Feb 1;10(1):1-7. 134

135. • The literature concluded that a very low intake of sugar
showed very low caries scores, and those that included a
very high amount of sugar in their diets developed high
numbers of carious lesions.
135

136. • Dietary sucrose also may have an effect on plaque
accumulation and bacterial population.
• The results of a study conducted by Carlsson and Egelberg
found plaque formation during intake of sucrose was much
thicker and heavier than that formed during glucose
supplementation.
Carlsson J, Egelberg J. Effect of diet on early plaque formation in man. Odontol
Revy. 1965;16:112–125 136

137. • Various studies have concluded a reduction in the amount
of lactobacilli and/or streptococcus mutans in plaque and
saliva when sucrose intake is low, and an increase in these
microorganisms during a sucrose-rich diet.
Leme AP, Koo H, Bellato CM, Bedi G, Cury JA. The role of sucrose in cariogenic
dental biofilm formation—new insight. Journal of dental research. 2006 Oct
1;85(10):878-87.
137

138. • Restricted carbohydrate intake also may have a negative
effect on the oral cavity. It encourages the breakdown of fat
stored for energy instead of glucose, a process known as
ketosis or dietary ketosis.
• The breakdown of fats results in three different molecules
called ketones. The third ketone, acetone, cannot be used
by the body and is excreted in the urine and exhaled by the
lungs, causing halitosis.
138

139. • Chronic oral malodor is a common dental problem and
may cause patients to seclude themselves from social
activities fearing the shame the condition brings.
139

140. NUTRITIONAL HEALTH PROGRAMS IN
INDIA
1. Special nutrition programme –
• It was started in 1970 for the nutritional benefit of
children below 6 years of age, pregnant and nursing
mothers.
• Operated in Urban slums, tribal areas and backward rural
areas.
• Supplementary nutrition is provided for 300 days every
year.
• Children under 6 years – 300kcal, 10-12g protein
• Pregnant and lactating women – 500kcal, 25g protein
140

141. • Initially the program was under the Central Government.
• The responsibility was later shifted to the State
Government in the fifth five year plan under the Minimum
Needs Program.
• Now the special nutrition program is integrated with the
ICDS (Integrated Child Development Services).
141

142. 2. The Balwadi Nutrition Programme (BNP) –
• was started in 1970. It is operated through Balwadis and
day-care centres for the benefit of children in the age
group of 3-6 years in rural areas.
• It is under the overall charge of the Department Of Social
Welfare.
• Four national level organizations including Indian Council
of Child Welfare are given grants to implement the
programme.
• The supplementary nutrition consisting 300 calories and
10 g of protein per child per day.
142

143. 3. Mid-day meal scheme –
• the National Programme of Nutritional Support to Primary
Education (NP-NSPE) was launched as a Centrally
Sponsored Scheme on 15th August 1995, initially in 2408
blocks in the country.
• By the year 1997-98 the NP-NSPE was introduced in all
blocks of the country.
• It was further extended in October 2002 to cover children
studying in Education Guarantee Scheme and Alternative
and Innovative Education centres.
143

144. • Its objective was universalization of primary education by
enhancing enrollment, retention and attendance and
simultaneously improving nutritional levels among
children.
• Improving the nutritional status of children in classes I-V
in Government Local Body and Government aided schools.
• A cooked mid-day meal with minimum 300 calories and 8
to 12 grammes of protein.
144

145. PUBLIC HEALTH SIGNIFICANCE
Burden-
• As per NFHS-3 (National Family Health Survey), ninety-six
percent of children under age five have ever been
breastfed, but only one-quarter of last-born children who
were ever breastfed breastfeeding within one hour of
birth.
• Almost half of children under age five years (48 percent)
are chronically malnourished. One out of every five
children in India under age five years is wasted.
145

146. • Forty-three percent of children under age five years are
underweight for their age. More than half (54 percent) of
all deaths before age five years in India are related to
malnutrition.
• Mild to moderate malnutrition contributes to more deaths
(43 percent) than severe malnutrition (11 percent). Iron
deficiency anaemia is an important condition in India with
seven out of every 10 children age 6-59 months in India
are anaemic.
146

147. • Three percent of children age 6-59 months are severely
anaemic, 40 percent are moderately anaemic, and 26
percent are mildly anaemic.
• Just under half of children age 6-59 months live in
households using adequately iodized salt. Among adults,
36 percent of women have a BMI below 18.5, indicating a
high prevalence of nutritional deficiency.
• Among women who are thin, almost half (45 percent) are
moderately or severely thin.
147

148. • Thirteen percent of women are overweight or obese (10 percent
are overweight and 3 percent are obese.
• The “excess” and “deficiency” of nutrition both are equally
harmful and has long lasting effects on individual, family and
community health.
• Thus it is of utmost importance to address this issue to make
community aware of concepts of healthy nutrition.
NFHS3.http://www.rchiips.org/nfhs/nutrition_report_pdf. Accessed on 16th July 2016
148

149. CURRENT SCENARIO
• Changing foods habits with reduced physical activity is
growing phenomenon around the world. Increasing
production of processed food with high salt content is also
common.
• People are consuming more foods high in energy,
saturated fats, trans fats, free sugars or salt/sodium, and
many do not eat enough fruit, vegetables and dietary fibre
such as whole grains.4
Healthy diet. WHO. http://www.who.int/mediacentre/factsheets/fs394/en/.
Accessed on 17th July 2016. 149

150. NATIONAL FAMILY HEALTH SURVEY-4
2015 -16
150

151. 151

152. CONCLUSION
• A holistic approach is needed to promote the concept of
healthy nutrition in whole country.
• Multi-sectoral innovative approaches to involve all age
groups, keeping in view cultural diversity in food habits
and earning capacity is required to make people aware of
importance of healthy nutrition.
• The initiative should be taken right from childhood in
schools, child care centers and families so that foundation
stone of healthy eating habits is laid down in right age and
can be propagated in future generations well.
152

153. • Availability of nutritious foods at low cost should be
ensured by policy making, mobilizing community and
health education.
153

154. REFERENCES
• Hardy K, Brand-Miller J, Brown KD, Thomas MG, Copeland
L. The importance of dietary carbohydrate in human
evolution. The Quarterly review of biology. 2015
Sep;90(3):251-68.
• Yudkin J. Evolutionary and historical changes in dietary
carbohydrates. The American journal of clinical nutrition.
1967 Feb 1;20(2):108-15.
• K Park, Textbook of Preventive and Social medicine, 23rd
edition.
• U Satyanarayana. Text Book of Biochemistry. Elsevier
Health Sciences, 2014.
• S.S. Hiremath. Textbook of Preventive Dentistry. 1st edition.
154

155. • Biochemistry: Instant Notes for Medical Student. Jaypee
Brothers Publishers, 2006.
• Richard A. Harvey (Ph. D.), Richard A. Harvey, Denise R.
Ferrier. Biiochemistry. Lippincott Williams & Wilkins, 2011
- Medical.
• Karen C. Timberlake (2012) Chemistry : An Introduction to
General, Organic, and Biological Chemistry - 11th ed.
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• Healthy diet. WHO.
http://www.who.int/mediacentre/factsheets/fs394/en/.
Accessed on 17th July 2016
155

156. • Kishore J. National health programs of India: National
Policies and legislation related to Health. Century
Publications. 11th Edn. 2014. New Delhi.
• Joshi A. Rashmi. A Textbook of Practical Biochemistry.B.
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156

157. 157