Dietary fat

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Lecture 9 Dietary fat Lifestyle
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Lipid transport in the bloodstream

• Lipoproteins

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Lipoproteins

• transport vehicles for FAT in the bloodstream
• most LIPOPROTEINS synthesised in LIVER

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Lipoproteins

• 4 classes CHYLOMICRONS
• VLDL
• LDL
• HDL

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Lipoproteins

• each contains
• TRIGLYCERIDES
• PHOSPHOLIPID
• CHOLESTEROL
• bound with protein

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LIPOPROTEINS

• icture of lipoprotein from Whitney Rolfes

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1. Very Low Density Lipoprotein

• VLDL
• synthesised in liver
• carries triglyceride from liver to
• periphery via bloodstream
• sensitive to dietary saturated FAT

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2. Low Density Lipoprotein

• LDL
• main carrier of cholesterol in blood
• cholesterol mainly synthesised in liver

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VLDL ? LDL

• cholesterol first built into VLDL with
  Triglycerides
• once VLDL discharges its Triglyceride
• becomes LDL cholesterol rich

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Lipoproteins

• LIVER
• Cholesterol
• cell membranes bile acids
• (via VLDL LDL) (in liver)

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Function of LDL

• transport cholesterol
• deposits on artery wall
• bad cholesterol
• Atherosclerosis (Arteriosclerosis)

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3. High Density Lipoprotein

• HDL
• synthesised in LIVER
• not a breakdown of other lipoproteins

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Function of HDL

• reverse cholesterol transport
• removes cholesterol to liver for excretion
• good cholesterol

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Lipid Storage

• FAT stored as Triglyceride in Adipose tissue
• dietary fat delivered to adipose tissue
• from liver in VLDL
• from intestines in Chylomicrons

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Lipid Storage

• stored Triglyceride hydrolysed to free fatty
  acids released into blood when needed for ENERGY

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Mobilisation of fat

Adipose cell
Triglycerides
FFA Glycerol
Liver
via bloodstream
Muscle
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Dietary Fat Lifestyle Diseases

• 1. Saturated fat blood cholesterol
• only affects those with genetic propensity
• excess LDL cholesterol is deposited on artery
  walls

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Dietary Fat Lifestyle Diseases

• excess LDL cholesterol comes from excess
  saturated fat intake via excess VLDL production
• excess dietary ? excess VLDL ? excess LDL
• FAT cholesterol cholesterol

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Dietary Fat Lifestyle Diseases

• SPECIFIC saturated fatty acids elevate blood
  cholesterol
• lauric acid (12 carbons)
• myristic acid (14 carbons)
• palmitic acid (16 carbons)
• stearic acid (18 carbons) ???
• ?how
• preferential incorporation into VLDL in liver

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Food sources of saturated FAs

• Fatty Acids Food sources
• Lauric Acid fatty meats
• Myrisitic Acid high fat dairy products
• coconut milk
• Palmitic Acid palm oil
• Stearic Acid chocolate (cocoa bean)

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Atherosclerosis(vascular disease)

• deposition of cholesterol on artery walls
• deposited where arteries branch
• affected arteries
• aorta
• carotid arteries
• femoral arteries

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Risk factors for Atherosclerosis

• elevated blood cholesterol
• begins fatty plaque formation
• leads to artery occlusion
• artery walls become less elastic (mineral
  deposition)
• Atherosclerosis/Arteriosclerosis
• hardening of the arteries
• dietary influence from SATURATED FAT

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Recommended reading

• Whitney Rolfes (2005)
• Understanding Nutrition 10th Ed.
• Chapter 5. The Lipids Triglycerides,
  Phospholipids Sterols
• Chapter 18. Diet and Health
• Wahlqvist (2002)
• Food Nutrition 2nd Ed.
• Chapter 27. Atherosclerosis and coronary heart
  disease