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FATSFATS(LIPIDS)(LIPIDS)

Department of Applied ScienceDepartment of Applied ScienceKing Saud University/ Community King Saud University/ Community

CollegeCollegeBy: Murad SawalhaBy: Murad Sawalha

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FATS (LIPIDS)FATS (LIPIDS)

• Nature of fats:Nature of fats:– Are storage form of concentrated fuelAre storage form of concentrated fuel– Fats are either solid or liquid oilsFats are either solid or liquid oils– Either saturated fats or unsaturated Either saturated fats or unsaturated – Not soluble in water, greasy.Not soluble in water, greasy.– Lipids are the chemical group name for Lipids are the chemical group name for

organic substances of a fatty nature (fats, organic substances of a fatty nature (fats, oil, & other fat related compounds)oil, & other fat related compounds)

– Fats are composed of the same elements Fats are composed of the same elements composing CHO, i.e. C, H, Ocomposing CHO, i.e. C, H, O

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Classes of fats (lipids)Classes of fats (lipids)

• Triglycerides:Triglycerides:

- - a class of lipids composed of a glycerol a class of lipids composed of a glycerol molecule as its backbone with 3 fatty acids molecule as its backbone with 3 fatty acids attached.attached.

- account for approximately 98% of the lipids - account for approximately 98% of the lipids in food and are the major storage form of fat in food and are the major storage form of fat in the body.in the body.

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Classes of fats (lipids)Classes of fats (lipids)• Fatty acids (F.A):Fatty acids (F.A): - They are the main building blocks of fats.- They are the main building blocks of fats.

- FA are Classified by their chain length:- FA are Classified by their chain length: 1) Short chain have (2-4) carbon atoms1) Short chain have (2-4) carbon atoms 2) Medium chain have (6-10).2) Medium chain have (6-10). 3) Long (more than 12) carbon atoms.3) Long (more than 12) carbon atoms.

- The chains are made up of carbon atoms with a - The chains are made up of carbon atoms with a methyl group (-CH3) on one end & a carboxyl group (-methyl group (-CH3) on one end & a carboxyl group (-COOH) on the other end.COOH) on the other end.

- Fatty acids have 2 significant characteristic: - Fatty acids have 2 significant characteristic: saturation & essentiality.saturation & essentiality.

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FATTY ACIDS FATTY ACIDS

• Saturated (filled with H atoms) and Saturated (filled with H atoms) and unsaturated (unfilled with H atoms unsaturated (unfilled with H atoms at one or more spots)at one or more spots)

• Essential F.A (can not be Essential F.A (can not be synthesized by the body) and Non synthesized by the body) and Non Essential (can be synthesized by Essential (can be synthesized by the body) the body)

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FATTY ACIDSFATTY ACIDSSaturationSaturation

• Saturated F.As: saturated with H atoms, no Saturated F.As: saturated with H atoms, no double bonds, heavier, denser and more double bonds, heavier, denser and more solid, mostly of animal origin (e.g. meat fat, solid, mostly of animal origin (e.g. meat fat, eggs, dairy, … etceggs, dairy, … etc

• Unsaturated F.As: with one or more double Unsaturated F.As: with one or more double bonds, less heavier (a liquid oil)bonds, less heavier (a liquid oil)

1) Some are monounsaturated fat (olives & 1) Some are monounsaturated fat (olives & olive oils, peanuts & peanuts oil, canola oil olive oils, peanuts & peanuts oil, canola oil (rapeseed), almonds, pecans, avocado(rapeseed), almonds, pecans, avocado

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FATTY ACIDSFATTY ACIDS SaturationSaturation

2) Polyunsaturated F.As: having two or 2) Polyunsaturated F.As: having two or more double bonds (e.g. Vegetable oils, more double bonds (e.g. Vegetable oils, safflower, corn, cottonseed, soybean)safflower, corn, cottonseed, soybean)

• Fats from plants are usually Fats from plants are usually unsaturated except coconut, palm oilunsaturated except coconut, palm oil

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FATTY ACIDSFATTY ACIDSEssentialityEssentiality

• Essential fatty acids::Essential fatty acids::

- They are essential nutrients:- They are essential nutrients:

1)Its absence cause a specific deficiency disease1)Its absence cause a specific deficiency disease

2)The body can not manufacture them and must 2)The body can not manufacture them and must obtain them from outside in the dietobtain them from outside in the diet

- The only fatty acids known to be essential for - The only fatty acids known to be essential for complete human nutrition are the polyunsaturated complete human nutrition are the polyunsaturated fatty acids linoleic & linolenicfatty acids linoleic & linolenic..

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FATTY ACIDSFATTY ACIDSEssentialityEssentiality

• Linoleic acid is found in vegetable oils: Linoleic acid is found in vegetable oils:

(DRIs): (17 gm / day for men)(DRIs): (17 gm / day for men)

(12 gm / day for women)(12 gm / day for women)

• Linolenic acid is found in milk, soyabean Linolenic acid is found in milk, soyabean

(DRIs): (1.6 gm / day for men)(DRIs): (1.6 gm / day for men)

(1.1 gm / day / women)(1.1 gm / day / women)

• They have important functions: They have important functions:

- Tissue strength, cholesterol metabolism, muscle tone, blood - Tissue strength, cholesterol metabolism, muscle tone, blood clotting, & heart actionclotting, & heart action

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LIPOPROTEINSLIPOPROTEINS

• FAT + PROTEIN (APOPROTEIN)FAT + PROTEIN (APOPROTEIN)

• Major vehicles in transport function in bloodMajor vehicles in transport function in blood

• Lipoproteins contain triglycerides, cholesterol, Lipoproteins contain triglycerides, cholesterol, other minerals and vitaminsother minerals and vitamins

• Their density is proportionate to the protein Their density is proportionate to the protein load.load.

• The higher protein load, the higher lipoproteins The higher protein load, the higher lipoproteins density.density.

• The higher the fat load, the lower the lipoprotein The higher the fat load, the lower the lipoprotein density. density.

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LIPOPROTEINSLIPOPROTEINS

• Low density lipoproteins (LDLs): carry fat & Low density lipoproteins (LDLs): carry fat & Cholesterol to the cells of the bodyCholesterol to the cells of the body

• High density lipoproteins (HDLs): carry free High density lipoproteins (HDLs): carry free cholesterol from body tissues to the liver to be cholesterol from body tissues to the liver to be broken and then excreted.broken and then excreted.

• Lipids are associated with lipids disorders, blood Lipids are associated with lipids disorders, blood vessels, and heart diseases (atherosclerosis)vessels, and heart diseases (atherosclerosis)

- Hyperlipidemia: the condition of an elevated - Hyperlipidemia: the condition of an elevated level of blood fats.level of blood fats.

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CHOLESTEROLCHOLESTEROL

• IT IS NOT A FATIT IS NOT A FAT• IT IS FROM A DIFFERENT CHEMICAL GROUP IT IS FROM A DIFFERENT CHEMICAL GROUP

CALLED STEROLS CALLED STEROLS • It is vital in human metabolismIt is vital in human metabolism• Present in all animal tissue particularly egg Present in all animal tissue particularly egg

yolk, organ meat as liver and kidneys and yolk, organ meat as liver and kidneys and meatmeat

• Not found in plants foodNot found in plants food• It is synthesized in the liver, adrenal cortex, It is synthesized in the liver, adrenal cortex,

skin, intestines, testes and ovariesskin, intestines, testes and ovaries

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CHOLESTEROLCHOLESTEROL

• The body does not need cholesterol from The body does not need cholesterol from outside, so there is no biological outside, so there is no biological requirements for itrequirements for it

• Also no DRIs set for cholesterol consumptionAlso no DRIs set for cholesterol consumption

• It is connected with the occurrence of It is connected with the occurrence of coronary heart diseasescoronary heart diseases

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FUNCTIONS OF FATSFUNCTIONS OF FATS

1) 1) Energy: Energy:

- Its a fuel for energy production- Its a fuel for energy production

- Caloic (fuel )value of fats is 9 Kcal/ gm- Caloic (fuel )value of fats is 9 Kcal/ gm

- Storage form of body fuel (excess CHO is changed - Storage form of body fuel (excess CHO is changed into fats)into fats)

2) Essential nutrients: 2) Essential nutrients:

- Provide essential fatty acids for production of - Provide essential fatty acids for production of other fats and cholesterolother fats and cholesterol

- Aid in absorption of fat soluble vitamins- Aid in absorption of fat soluble vitamins

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FUNCTIONS OF FATSFUNCTIONS OF FATS

3) 3) Flavor and Satisfaction:Flavor and Satisfaction:

Some fat adds flavor to foods, & contributes Some fat adds flavor to foods, & contributes to a feeling of satisfaction after meal (low to a feeling of satisfaction after meal (low rate of gastric emptying and digestion)rate of gastric emptying and digestion)

4) Fat Substitutes: several fat substitutes are 4) Fat Substitutes: several fat substitutes are being marketed without added Kcalories, being marketed without added Kcalories, and not even absorbed, but gives the fat and not even absorbed, but gives the fat flavor e.g. simplesse, and olestraflavor e.g. simplesse, and olestra

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FAT in the bodyFAT in the body

• Fat in the body:Fat in the body:

1. Adipose tissue: supports, protects vital 1. Adipose tissue: supports, protects vital organs, under the skin (heat regulation), organs, under the skin (heat regulation), in myelin sheaths of nerves (relay nerve in myelin sheaths of nerves (relay nerve impulse)impulse)

2. Cell membranes structure: forms the 2. Cell membranes structure: forms the fatty center, regulates the cell fatty center, regulates the cell membrane transportmembrane transport

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FAT SOURCESFAT SOURCES

• Food Sources of Fat:Food Sources of Fat:1.1. Animal fats: animal sources (saturated fat) e.g. Animal fats: animal sources (saturated fat) e.g.

meat fat, dairy fat products (cream, ice-cream, meat fat, dairy fat products (cream, ice-cream, butter, cheese), egg yolk, red meat (veal, beef, butter, cheese), egg yolk, red meat (veal, beef, pork, lamb), poultry, shelfish, fishpork, lamb), poultry, shelfish, fish

2.2. Plant fat: Plant fat: - Mostly unsaturated; mono and polyunsaturated fat - Mostly unsaturated; mono and polyunsaturated fat - In vegetable oils (safflower, corn, cottonseed, - In vegetable oils (safflower, corn, cottonseed,

peanut, olives, soybeans)peanut, olives, soybeans) - Coconut & palm oils are exception (saturated fat)- Coconut & palm oils are exception (saturated fat)

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FAT SOURCESFAT SOURCES

3.3. Hydrogenated Fat: margarine and Hydrogenated Fat: margarine and shortenings, sometimes fortified with shortenings, sometimes fortified with vitamins A &Dvitamins A &D

Risks of high saturated fat diet and Risks of high saturated fat diet and cholesterol:cholesterol:

1.1. Some cancersSome cancers 3. diabetes 3. diabetes mellitusmellitus

2.2. Coronary heart diseasesCoronary heart diseases 4. obesity4. obesity

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FAT SOURCESFAT SOURCES• Characteristics of food sources:Characteristics of food sources:

• Food fats are classified into: visible and Food fats are classified into: visible and invisible fats, to help individuals become invisible fats, to help individuals become aware of all food sources of fat aware of all food sources of fat

• Visible fat: plain to see and include: butter, Visible fat: plain to see and include: butter, margarine, separate cream, salad oils, and margarine, separate cream, salad oils, and dressing, lard, shortenings, fat mealdressing, lard, shortenings, fat meal

• Invisible fat: include cheese, cream portion Invisible fat: include cheese, cream portion

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FAT SOURCESFAT SOURCES

• Of a homogenized milk, egg yolk, nuts, Of a homogenized milk, egg yolk, nuts, seeds, olives, avocados, lean meatseeds, olives, avocados, lean meat

• BODY NEEDS OF FAT:BODY NEEDS OF FAT:

• Dietry fat and healthDietry fat and health

• Not more than 20 – 35 % of the total Not more than 20 – 35 % of the total caloric requirements should come from fatcaloric requirements should come from fat

• Diseased individuals should stick to 15 – Diseased individuals should stick to 15 – 25 % to provide the needed F.F.25 % to provide the needed F.F.

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HEALTH PROMOTIONHEALTH PROMOTION

• The trends of health promotion and The trends of health promotion and disease prevention is through reduction disease prevention is through reduction of risk factors related to chronic diseasesof risk factors related to chronic diseases

• Excess dietary fat, particularly saturated Excess dietary fat, particularly saturated fat, cholesterol, hypertension, stress, fat, cholesterol, hypertension, stress, lack of exercise, obesity, diabetes lack of exercise, obesity, diabetes mellitus, elevated blood lipids all mellitus, elevated blood lipids all predispose to heart diseasespredispose to heart diseases

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DIGESTION OF FATDIGESTION OF FAT

1.1. In the Mouth: lingual lipase, secreted In the Mouth: lingual lipase, secreted from glands at the back of tongue, has from glands at the back of tongue, has little effect + mechanical breakdownlittle effect + mechanical breakdown

2.2. Stomach: little if any chemical Stomach: little if any chemical digestion by gastric lipase tributrinasedigestion by gastric lipase tributrinase

3.3. Small intestine: chemical digestion Small intestine: chemical digestion through 3 major sources:through 3 major sources:

a)a) Liver bileLiver bile b) pancreatic lipasesb) pancreatic lipasesc) intestinal enzymesc) intestinal enzymes

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DIGESTION OF FATDIGESTION OF FAT

a)a) Bile from the gall bladder: fat is Bile from the gall bladder: fat is emulsified by bile into small particles emulsified by bile into small particles with large surface are and lower surface with large surface are and lower surface tension in an alkaline mediumtension in an alkaline medium

b)b) Pancreatic enzymes:Pancreatic enzymes:I.I. Pancreatic lipase: powerful enzyme, Pancreatic lipase: powerful enzyme,

completes digestion of fats into FFA + completes digestion of fats into FFA + glycerol, monoglycerides, some fat glycerol, monoglycerides, some fat remain as such for excretionremain as such for excretion

II.II. Cholesterol estrase: on cholesterol estersCholesterol estrase: on cholesterol esters

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DIGESTION OF FATDIGESTION OF FAT

c)c) Enzymes from the small intestine:Enzymes from the small intestine:

Lecithinase which acts on lecithin Lecithinase which acts on lecithin (another lipid compound)(another lipid compound)

Absorption of fats: Absorption of fats:

MICELLESMICELLES

CHYLOMICRONSCHYLOMICRONS

Lymphatic circulationLymphatic circulation