The document summarizes the digestion of lipids in the human body. It discusses that lipids provide energy and fat-soluble vitamins. The major dietary lipids are triglycerides, cholesterol, and phospholipids. Lipid digestion begins in the mouth through the action of lingual lipase, and continues in the stomach with gastric lipase. In the small intestine, lipids are emulsified by bile salts and the actions of pancreatic lipases further break down triglycerides into fatty acids and monoacylglycerols through a multi-step process. Digestion of lipids is only partial, with some triglycerides and cholesterol esters remaining undigested.

1. DIGESTION OF
LIPIDS
DIGESTION OF LIPIDS 1

2. • Storage form of
• energy
• Conc. source of energy
• Intake necessary to meet
the requirements of fat
soluble vitamins and
essential fatty acids
DIGESTION OF LIPIDS 2

3. The major dietary lipids are
TRIACYLGYLCEROL
CHOLESTEROL
PHOSPHOLIPIDS
DIGESTION OF LIPIDS 3

4. • Average Indian diet is
about 20-30 gm/ day
• Western diet 2-3
times higher level of
lipids.
DIGESTION OF LIPIDS 4

5. DIGESTION OF LIPIDS 5

6. DIGESTION IN MOUTH
• Very little amount of digestion
takes place in the mouth
because of lingual lipase .
• It has an optimum ph of 2.5-5
• Its action continues in stomach
also.
DIGESTION OF LIPIDS 6

7. • It acts mainly on short chain
triglycerides.
• SCTs are present in milk, butter and
ghee.
• It’s action is more
significant in newborn
babies. DIGESTION OF LIPIDS 7

8. DIGESTION IN STOMACH
• Gastric lipase is an important
lipid digesting enzyme in
stomach.
• It has an optimum ph of 5.4
• Secreted by Chief cells.
• Upto 30% digestion of TAG
occurs here. OF LIPIDS
DIGESTION 8

9. DIGESTION IN
INTESTINE
• Emulsification is the pre-
requisite for digestion.
DIGESTION OF LIPIDS 9

10. • The lipids are dispersed
into smaller droplets
where surface tension is
reduced and surface area
is increased.
• Enhances enzyme activity.
DIGESTION OF LIPIDS 10

11. It is favoured by:
1. Action of Bile salts
2. Peristalsis movement
3. Phospholipids
DIGESTION OF LIPIDS 11

12. • Bile salts prsent in bile are
sodium glycocholate and
sodium taurocholate which
lowers surface tension.
• Acts as detergents
DIGESTION OF LIPIDS 12

13. • Bile (pH 7.7) entering the
duodenum neutralizes the
acid chyme from the
stomac and provides ph
favourable for action of
Pancreatic enzymes
DIGESTION OF LIPIDS 13

14. Lipolytic enzymes in intestines
1. Pancreatic lipase
2. Co-lipase
3. Cholesterol esterase
4. Phospholipase A2
DIGESTION OF LIPIDS 14

15. DIGESTION OF (TAG)
TRIGLYCERIDES
• Pancreatic lipase hydrolyze
fatty acids esterified to the
1st and 2nd C atoms of glycerol
forming 2 DAG and 2
molecules of fatty acid.
DIGESTION OF LIPIDS 15

16. DIGESTION OF (TAG)
TRIGLYCERIDES
G Fatty Acid1 G
l l
y y Fatty Acid1
Lipas
c eH 0 c Fatty Acid2 +
e Fatty Acid2 2 2 e
Fatty Acid3
r r
o o
l Fatty Acid3 l
DIGESTION OF LIPIDS 16 2 Free Fatty Acids
Triglyceride 2-Monoglyceride

17. • An isomerase shifts the ester
bond from position 2 to 1.
G G Fatty Acid2
l ISOMERAS l
y E y
c Fatty Acid c
2
e e
r r
o o
l l
2-MAG 1-MAG
DIGESTION OF LIPIDS 17

18. • The bond in the 1st position is
then hydrolysed by Lipase to
form free glycerol and fatty
acids.
G
G Fatty Acid2 l
l y
y LIPASE c Fatty Acid2
c e +
e r
r o
o l
l
1-MAG DIGESTION OF LIPIDS 18

19. Dietary Fat
arge TG droplet)
BILE SALTS
2-MAG +
Lipase (78%)
1-MAG +
Lipid emulsion
(6%)
GLYCEROL
+ FFA
DIGESTION OF LIPIDS 19

20. • Digestion of TAG is partial
or incomplete.
• Cholesterol esters may be
hydrolysed to cholesterol
and fatty acids.
• Cholesterol esterase
• Phospholipase A2
DIGESTION OF LIPIDS 20

21. thANk
yoU!!!!
DIGESTION OF LIPIDS 21