Subject : Nutrition, Unit- VI This topic provides brief knowledge about lipid metabolism and it is prepared according to INC syllabus for first year BSc Nursing Students.

1. LIPID METABOLSIM
BY, MS.PRIYANKA GOHIL
M.Sc. (N)
Nursing Tutor, MBNC

2. Lipids Digestion
• Most of the fat in te human diet
is in the form of
“TRIGYCEROL” (TAG) which
consists of three fatty acids
linked o glycerol.
• In the digestive tract, TAG is
hydrolysed by the enzyme
pancreatic lipase, to release
free fatty acids and
monoglycerides.

3. Emulsification and digestion
solubility colipase
• The key issue in the digestion
and absorption of fats is one of
solubility.

4. Emulsification and digestion
Lipids are hydrophobic and thus
are poorly soluble in the aqueous
environment of the digestive
tract.

5. Emulsification and digestion
The digestive enzyme,
“PENCREATIC LIPASE” is water
soluble and can only work at the
surface of fat globules.

6. Emulsification and digestion
Digestion is greatly aided by
“EMULSIFICATION”, the
breaking up of fat globules in to
much smaller “EMULSION
DROPLETS”.
Bile salts and phospholipids are
amphipathic moleciles that are
present in the bile.

7. Emulsification and digestion
Motility in the small intestine
breaks fat globules apart into
small droplets that are coated
with bile salts and
phospholipids, preventing the
emulsion droplets from re-
associating.

8. Emulsification and digestion
The emulsion droplets are where
digestion occurs.
Emulsification greatly increases the
surface area where water-soluble
lipase can work to digest TAG.
Another factor that helps is
“COLIPSE” an amphipathic protein
that binds and anchors pancreatic
lipase at the surface of the emulsion
droplet.

9. Micelles
After digestion, monoglyverides are
and fatty acids associate with bile
salts and phospholipis to form
“MICELLES”.
Micelles are 200 times smaller than
emulsion dropletes.

10. Micelles
Micelles are necessary because they
transport the poorly soluble
monoglycerides and fatty acids to
the surface of the enterocytes where
they can be absorbed.
As well, micelles contain fat soluble
vitamins and cholesterol.

11. Micelles
Micelles are constantly breaking down and re-
forming
feeding a small pool of monoglycerides and fatty
acid that are in solution.
only freely dissolved monoglycerides and fatty
acids can be absorbed NOT the micelles
Bcoz of nonpola nature, monoglycerides and fatty
acids can just diffuse across the plasma
membrane of the enterocyte.
some absorption may be facilitated by specific
transport proteins

12. Micelles &
Fat absorption

13. Choleterol absorption
• Intestinal
cholesterol
absoprtion is
important because
of the clinical
relevance of
choleterol.
• LDL- circulation-
arteriosclerosis.

14. Choleterol absorption
100%cholesterol from
liver50% and diet50%
half of that (50%) only
absorbed
other half (50%)
eliminated in the
feces

15. Lipids Disorder
• Lipids deficiency (Shortage in
Lipids intake)
• Lipids exceeding (Overtaking
in Lipids intake)

16. Lipids Deficiency
• Fat should comprise of 3% of total
calories to prevent fatty acid
deficiency
• Fatty acid deficiency syndromes
–Dry scaly skin, dermatitis (Linoleic
acid deficiency)
–Hand tremors (Prostaglandin
deficiency)
–Inability to control blood pressure

17. Lipids Exceeding
• Fat should comprise not more than
30% of total calories to prevent
lipids exceeding
• To prevent overtaking, we should
consume fat breakdown (% total
calories)
–<8% from saturated fat
–10% from polyunsaturated fat
–10-15% from monounsaturated fat

18. Body Mass Index
• Current best single gauge for body fat
• BMI =(Weight in Kg)/((Height in cm
)(Height in cm)) X 10,000
BMI Weight Status
Below 18.5 Underweight
18.5 – 24.9 Healthy Weight
25.0 – 29.9 Overweight
30.0 and Above Obese

19. Health Problems
• Energy Intake > Energy needed =
Lipids overtaking
• Develop medical problem
–Cancer
–Heart disease
–Diabetes
–Obesity
–High blood pressure
–High blood cholesterol

20. Prevention of Lipid Disorder
• Reduce fat
–Cut down on high fat foods
–E.g. butter, margarine, oil,
mayonnaise
• Consume small amounts of
unsaturated fats
–Do not eliminate fat completely
since it is high in calories

21. Prevention of Lipid Disorder
• Limit added sugar and alcohol
–Added sugar and alcohol are ‘empty
calories’
• Watch portions of all food
–‘fat free’ ≠ ‘calorie-free’
• Drink at least 8 glasses of water
everyday
–Water is calorie-free, refreshing, and
filling

22. Prevention of Lipid Disorder
• Increase intake of vegetables,
fruits, and whole grains
–Loaded with fiber
–Contain high amounts of vitamins,
minerals, and phytonutrients
• Include low-fat protein-rich food
with every meal
–E.g. tofu, beans, eggs, and fish

23. Prevention of Lipid Disorder
• Slow down when eating
–Too fast eating will exceed calorie
needs before realizing we are full