A lucid presentation on Nutritional aspects of Lipids for medical , dental , pharmacology and biotechnology students to facilitate easy-learning.

1. Nutritional aspects of Lipids
Dr. Rohini C Sane

2. Nutritional importance of Lipids
• Visible fat (consumed as such): butter,ghee,oils
Recommended daily intake of visible fat:20g(10%of calories)
• Invisible fat(fat present as part of other food items) :
egg ,fish, meat ,nuts,cereals , oil seeds.
More than half of essential fatty acids in Indian diet are
present in the form of invisible diet.
100g of cereals contain 1gm of fat.

3. Nutritional functions of lipids
1. supply Triglycerides/neutral fat constitute 90% dietary
lipids (i.e. fats and oils) which is a concentrated source
of energy / fuel to the body.
2. 40% of calories needed by the human body is derived
from lipids (in developing countries<10%). Fat intake is
lowest in Kerala and Orissa.
3. increase taste ,palatability of food and are the favoured
cooking medium.
4. provide essential fatty acids.
5. provide fat soluble vitamins A, D,E and K.

4. Function of Triglycerides
• Triglycerides function a as fuel reserves of animals.
• The fat reserve of a normal human (men 20%, women
25% by weight) is sufficient to meet bodies calorie
requirement for 2-3 months.
• Adipocytes of adipose tissue predominantly found in
subcutaneous layers and in abdominal cavity are
specialised for storage of triglycerides. The fat is
stored in form of globules dispersed in the entire
cytoplasm.

5. Functions of Phospholipids:1
1. important components of cell membranes in association
with proteins and regulate membrane permeability.
2. participate in the absorption of fat from the intestine.
3. essential for biosynthesis of different lipoproteins and thus
participate in transport of lipids.
4. functions as lipotropic factors prevent accumulation of fat
in liver (fatty liver).
5. help in the reverse transport and removal of cholesterol
from the body.

6. Functions of Phospholipids:2
6. Phosphotidyl Lecithin: storage form of body’s choline, prevents
respiratory distress syndrome.
7. Phosphotidylinositol: important component of cell membranes,
source of second messengers of inositol triphosphate and diacyl
glycerol which mediate action of hormones(e.g. oxytocin, vasopressin).
8. Cardiolipin: important component of inner mitochondrial membrane,
maintain mitochondrial electron transport chain thus participate in
cellular respiration.
9. Biosynthesis of prostaglandins, prostacyclins and thromboxanes
(phospholipids contribute Arachidonic acid).
10. Cephalin : participate in blood clotting , important component of
inner mitochondrial membrane, maintain mitochondrial electron
transport chain thus participate in cellular respiration.

7. Nutritional Importance of fatty acids
• Essential to take saturated , monounsaturated and
polyunsaturated fatty acids (combination of
groundnut oil ,ghee and vegetable oil).
• Total dietary fat content : 20-25 g oils /+ 3 g PUFA
• Total dietary fat content : SFA : MUFA : PUFA (1:1:1)
• Increase in dietary intake of PUFA increases free
radicals which are injurious to health .Therefore ,
dietary intake of PUFA should not exceed 30%.

8. Nutritional sources of fatty acids
Type of fatty acid Nutritional source
Long chain saturated fatty acids Palmitic acid, Stearic acid
Mono unsaturated fatty acids(MUFA) Oleic acid, Palmoleic acid
Medium chain fatty acid Lauric acid, Myristic acid
Polyunsaturated fatty acids(PUFA) Vegetable oils,fish oils
Animal fat (fat present in meat ,chicken) Butter

9. Essential fatty acids

10. Essential Fatty acids
• Essential fatty acids(EFA):Unsaturated fatty acids which
cannot be synthesised in the human body therefore have
to be consumed in the diet.
• e.g. essential fatty acids : Linoleic acid, Linolenic acid
• e.g.Semi essential fatty acid: Arachidonic acid can be
synthesised from linoleic acid in the human body and in
some animal species (some amount is supplied through
the diet).

11. Dietary sources Essential Fatty acids
Rich sources of EFA :vegetable oils : sunflower oil ,cotton
seed oil,soya bean oil, corn oil
Poor sources of EFA : fat of animal origin(except fish) :
butter ,fat of meat /pork /chicken
30% dietary fat : should contain Polyunsaturated fatty acids
(PUFA) + Antioxidant vitamin E + Carotenes
Very high dietary intake PUFA( i.e. totally replacing saturated
fatty acids) may not be advisable. This is due to the fact that
excess PUFA , unless accompanied by antioxidant vitamin E
and carotenes is believed to be injurious to the cells due to
overproduction of free radicals.

12. Functions of essential fatty acids (PUFA)
• Structural components of phospholipids and bio-membrane.
• precursor for biosynthesis of prostaglandins and leukotrienes.
• Esterification,transport,utilisation and excretion of cholesterol.
• Hypocholesterolemic (reduce serum cholesterol,have anti-
atherogenic effect) .Therefore unsaturated fat (vegetable oils
and fish oils)are to be preferred.
• prevent fat accumulation in the liver.
• maintain proper growth and reproduction in the organisms.
Excess of PUFA + Total replacement of saturated fat (deficiency of VitaminE and
Carotene) cause over production of free radicals leading to cell injury(deleterious
effects).

13. Deficiency manifestations of essential fatty acids
• reduce growth and reproduction
• increase BMR
• increase turnover of phospholipids
• Toad skin disease (Phrynoderma):
1. scaly dermatitis in posterior and lateral parts of limbs
and buttocks
2. poor wound healing
3. loss of hair

14. Structural aspects of Polyunsaturated fatty acids(PUFA)from
nutrient oils
The essential fatty acids ,more frequently called Polyunsaturated fatty
acids(PUFA). They are present in vegetable and fish oils.
Essential fatty
acids source
PUFA
Number of
Carbon
atoms in
chain
Family
Omega
Number of
Double
bonds
Position of
double
bonds
Dietary source
Linoleic acid 18 6 2 9,12 vegetable oils
Linolenic acid 18 3 3 9,12,15 vegetable oils
Arachidonic
acid
20 6 4 5,8,12,15 vegetable oils
Timnodonic
acid
20 3 5 5,8,11,14,17 Fish oils

15. Omega-3 and Omega-6 fatty acids
• Omega -3and Omega-6 fatty acids : are long chain Polyunsaturated
fatty acids(PUFA) with double bond beginning at 3rd (omega-3)and
6th(omega-6) position from the methyl end.
• Examples of Omega-3 fatty acids: Linolenic acid, Docosahexaenoic
acid(DHA), Eicosapentaenoic acid(EPA).
• Example of Omega -6 fatty acids: Arachidonic acid
• Functions of Omega -3 and Omega -6 fatty acids: to reduce serum
cholesterol and Triacylglycerols ,thereby decrease the tendency for
thrombosis,lower blood pressure . Omega -3 fatty acids from fish oils
decrease plasma lipoproteins ( VLDLand LDL) and thereby reduce the
risk of coronary heart disease (CHD).
• Infant formulas containing omega -3 fatty acids : promote brain
development

16. Coronary Heart disease and Omega -3-fatty acids
Omega -3-fatty acids from fish oils
decrease plasma lipoproteins( LDL,VLDL)
reduce risk of coronary heart disease(CHD)

17. Fatty acids in oils
Type of Fat or oil
Saturated fatty
acids(SFA) (%)
Mono unsaturated
fatty acids (MUFA)(%)
Polyunsaturated
fatty acids(%)
Butter 75 20 5
Sunflower oil 9 12 79
Cotton seed oil 26 19 65
Coconut oil 86 12 2
Ground nut oil 18 46 36
Butter /ghee contains short chain fatty acids .Coconut oils contain medium
chain fatty acids .Therefore they are absorbed and metabolised quickly.

18. Trans fatty acids (TFA)
Trans fatty acids(TFA) :
1. are present in diary products and hydrogenated edible oils.
2. possess double bonds and are formed during partial hydrolysis of
vegetable oils.
3. elevate serum LDL and lower serum HDL level .Thus they promote
atherosclerosis (atherogenic) and heart diseases.Therefore ,TFA should
be avoided in the diet as far as possible.
4. adversely affect endothelial function . Thus aggravate insulin resistance
and diabetes .
5. are widely used in food industry since they increase shelf-life of fried
food.
6. Fast food preparation , processed foods and bakery items have high
content of TFA .Hydrogenated vegetable oils are used for their cooking.

19. Cholesterol in nutrition
• Animal food items are the only dietary source of cholesterol .
However Plasma cholesterol level is more dependent on amount
and types of fatty acids consumed than dietary cholesterol .
• Excess consumption of cholesterol (>250mg/day) leads to
coronary heart disease(CHD) and atherosclerosis.
• Consumption of excess of egg yolk (cholesterol)should be
prevented to reduce the risk of atherosclerosis.
• High fibres content of diet reduce serum cholesterol , LDL
fraction and raise HDL fraction .
• Whole cereals , pulses ,leafy vegetables and fruits contain good
quantity of fibres.

20. Nutritional importance of cholesterol
• Cholesterol:
1. plays role in membrane structure and functions.
2. present in abundance in nervous tissue (because of
high electric constant , poor conductor of heat and
electricity).
3. functions as an insulating cover for the transmission of
electrical impulses in the nervous tissue.
4. synthesis of bile acids , vitamin D and steroid
hormones(e.g. progesterone ,oestrogen , Testosterone) .

21. Cholesterol and heart diseases
• Atherogenic effect of Cholesterol and the risk of Coronary Artery Disease
(CAD) in people with hypercholesterolemia.
• To reduce risk of CAD: decrease dietary intake of cholesterol i.e.egg,
yolk ,liver brain ,kidney. Increase dietary intake of vegetables, cereals and
pulses as they lack cholesterol.
• Saturated fats raise serum cholesterol . Unsaturated fats (vegetable oils and
fish oils ) lower serum cholesterol therefore they are to be preferred in diet.
• Cholesterol absorption :
A. inhibited by vegetable sterols ,unsaturated fatty acids , high fibre content
(decrease LDL fraction, increase HDL fraction and serum Cholesterol)
B. elevated by saturated fatty acids.
• Good source of dietary fibres : whole cereals ,pulses and leafy vegetables

22. Cholesterol content of food items
Cholesterol content mg/100g
Brain 2000
Egg yolk 1330
Liver 300-600
Ghee 310
Hense egg 300
Butter 280
Meat 40-200
Milk 10
vegetables/Pulses/Cereals Lack cholesterol

23. Recommended daily dietary intake of fat
The ideal daily fat intake of visible fat : fulfils 15 - 20% of daily requirement of
calories ,out of which 25-30% of daily fat intake should be PUFA.
Total Lipids dietary intake:
A. For normal adults : 20-25 g oils+3 g PUFA /day
B. Pregnancy : 30g oils + 5 g PUFA /day
C. Lactation : 45 g oils + 7g /day
• Ratio of Total dietary fat content = SFA:MUFA:PUFA =1:1:1
• PUFA should not be more than 30% of total fat .Excess of PUFA is deleterious
due to production of free radicals which may be injurious to cells.
• Cholesterol intake < 250mg/day
• Consumption of dietary fats and oils is considered in terms of their
contribution towards the energy needs of the body.

24. Thank You