Fats

Why do we need fats?

• Contribute to texture and taste• Increase palatability of diet• For meeting the needs of

essential fatty acids (linoleic acid n – 6 and linolenic acid n – 3)

• Rich source of energy• Promote absorption of fat

soluble vitamins• Impart a feeling of fullness

and satisfaction and thus delay onset of hunger.

Essential Fatty Acids

• Queen of Vitamins• Poly Unsaturated Fatty Acids

(PUFA)• Linoleic acid (C18:2/n-6/PUFA)

and Linolenic acid (C18:3/n-3/PUFA) – must be present in a ratio of 5:1 to 10:1

• Omega 6 to Omega 3 (n6 : n3) ratio of 5:1 is desirable

Essential Fatty Acids

• High Omega 6 and low omega 3 ratio as in ground nut, sunflower, safflower oils (56:1) can predispose to – free radical injury, – angiotoxicity, – impaired immune function, – reduced glucose tolerance, – increased platelet aggreagation and – albuminuria

Essential Fatty Acids

• Omega 6 and Omega 3 ratio

– In coconut oil, [PUFA is only 2%] but this ratio is <5:1 (but more MCTs)

– In ghee it is 3:1– Mustard oil 1.5:1

Essential Fatty Acids

• Omega 3 or n-3

– In coconut oil, [PUFA is only 2%] but this ratio is <5:1 (but more MCTs)

– In ghee it is 3:1– Mustard oil 1.5:1

Long Chain Fatty AcidsEFAs are converted to LCFAs by a

series of chemical reactions called elongation and desaturation.

• LCPs from n-6 series derived from linoleic acid are – arachidonic acid (ARA) and – adrenic acid (ADA).

• LCPs from n-3 series derived from alpha linoleic acid are – ecosa pentanoic acid (EPA) and – decosa hexanoic acid (DHA).

Long Chain Fatty AcidsEFAs are converted to LCFAs by

a series of chemical reactions called elongation and desaturation.

• LCPs are the building blocks of brain lipid.

• Deficiency of LCPs may lead to comorbid conditions like dyslexia, dyspraxia and hyperactivity

Types of fat

• Visible : – Fats that are used as such

at the table or in cooking• Eg: Veg. oils, vanaspathi,

ghee,butter etc.

• Invisible :– Fats that are present as

and integral components of different foods• Eg. : cereals, animal foods

Component of fat

• Total should be 15 – 30 % and 1-3 % of calories should be from EFAs

• Avg. Indian foods supply 25-30% calories as fat. Diets of young children and adolescents should contain only 25 g/d of fat

• Not more than 10% of energy should be from essential fatty acids /SFA and 10% should come from MUFA and 10% from PUFA

Fatty Acids - Types

• Saturated: Lauric acid (C12), Myristic acid (C14), Palmitic acid (C16) and Stearic acid (C18) – Animal fats– Short and medium chained

saturated FAs are easily absorbed– Excess of MCTs can be atherogenic

• Monounsaturated fats: – Oils from palm, seseme, groundnut,

cotton seed, olive.

Fatty Acids - Types

• Polyunsaturated fats: – Only in plant foods– All vegetable oils rich in Linoleic

(n-6)– - linolenic (n-3) is present only

in mustard and soyabean oils and as invisible oil in legumes/pulses, mustard and fenugreek seeds (methi) & GLVs

– Fish and fish oils provide biologically more active form of n-3 linolenic acid

Fatty acid compositionsItem SFA % MUFA % PUFA %

n6 n3

Coconut oil 92 6 1.6 0.4

Corn oil 13 25 61 1

Groundnut oil 18 49 33 0

Olive oil 14 8 1

Sunflower oil 11 20 69 0

Safflolower oil 10 13 77 0

Palmolein 40 48 11 1

HVO 76 19 3 2

SATURATED MONO UNSATURATED

POLY UNSATURATEDLINOLEIC (N - 6) LIONOLENIC (N-3)

•Coconut•Palm kernel•Ghee•Butter •Vanaspathi

•Red palm oil•Palmolein•Groundnut•Ricebran•Saseme

Low: • Red palm oil•Palmolein

Medium:•Groundnut•Ricebran•Seseme

•Mustard•Soya bean

Medium Chain Triglycerides• C8 - C10 Fatty Acids• They are absorbed directly into

the portal vein even during fat malabsorption.

Cholesterol

• Essential component of body tissues and lipoproteins

• Forms nearly 0.2 % of body weight• It has no calorific value• Hypercholesterolemia – esp. LDL

predisposes to coronary heart disease• Heredity, smoking, sedentary habit,

emotional stress, hormonal imbalance, diet, diabetes etc. predispose to hypercholesterolemia.

Cholesterol

• Endogenous : Synthesized from 2 carbon fragments like acetate, acetic acid, acetyl CoA, etc.

• Exogenous : Derived from food

Cholesterol• Excess cholesterol is converted to bile acids

and excreted into intestine and eliminated as coprosterol

• Dietary fiber reduced cholesterol level• Cholesterol is present in bound and free

forms in a ration of 1:3• Bound to esters of fatty acids or lipoprotein

(LDL) cholesterol – 70%• That bound to alpha lipoprotein is high

density lipoprotein (HDL) cholesterol – 30%• Small amounts - bound to very low density

lipoproteins (VLDL) and rest to intermediate low density lipoproteins (ILDL) and very high density lipoproteins (VHDL)