1. Lipoproteins
Clusters of lipids associated with proteins that serve as transport vehicles for lipids in the lymph and blood

2. Lipoproteins Distinguished by size and density
Each contains different kinds and amounts of lipids and proteins
The more lipid, the lower the density
The more protein, the higher the density

3. Lipoproteins Chylomicrons VLDL – Very low density lipoprotein
IDL – Intermediate density lipoprotein
LDL – Low density lipoprotein
HDL – High density lipoprotein

4. Lipoproteins Distinguished by size and density
Each contains different kinds and amounts of lipids and proteins
The more lipid, the lower the density
The more protein, the higher the density

5. The Origins & Major Functions of Lipoproteins

6. Functions of Chylomicrons
Made by intestinal cells
Most of lipid is triglyceride
Little protein
ApoA-I, ApoA-II, ApoB-48, ApoC
Deliver fatty acids via lipoprotein lipase

7. Chylomicron remnants
Lipoprotein particle that remains after a chylomicron has lost most of its fatty acids
Taken up by liver
Contents reused or recycled

8. Further Delivery of Lipids in Body
Synthesizes & metabolizes lipids
“Central command center” for relation of lipid metabolism
Makes additional lipoproteins

9. Very-Low-Density Lipoproteins (VLDL)
Made by liver
Contains large amounts of triglyceride
Delivers fatty acids to cells
More dense than chylomicrons
A bit more protein (8%)
ApoB-100, ApoC, ApoE

10. Intermediate-Density Lipoproteins (IDL)
Lipoprotein that results from loss of fatty acids from VLDL
Major lipid is cholesterol esters
Proteins similar to VLDL but greater percentage (15%)
ApoB-100, ApoC, ApoE
Taken up by liver or remain in circulation
Converted to low-density lipoproteins (LDL)

11. Low-Density Lipoproteins (LDL)
“Bad” cholesterol; major lipid in LDL
Delivers cholesterol from liver to cells
Cell membranes
Hormone production
Protein (21%)
ApoB-100
Binds to specific LDL receptor
LDL receptors
Membrane-bound proteins that bind LDL, causing them to be taken up & dismantled

12. Effect of Diet on LDL Concentrations
Increase LDL
SFAs
Trans fatty acids
High cholesterol intake
Lifestyle factors
Genetics
Decrease LDL
High PUFA diet
Ω-3 fatty acids
Dietary fiber
Lifestyle factors
Genetics

13. High-Density Lipoproteins (HDL)
“Good” cholesterol; major lipid is phospholipid
Lipoprotein made by liver that circulates in the blood to collect excess cholesterol from cells
Lowest lipid-to-protein ratio
Protein (50%)
ApoA, ApoC, ApoE
Reverse cholesterol transport
Salvage excess cholesterol from cells
Transported back to liver

14. Effects of Diet on HDL Concentration
What raises HDL?
Uncertain if low carbohydrate diets offer protection
High MUFA intake
Moderate alcohol consumption
Lifestyle factors
Genetic factors influence HDL

15. Tangier Disease
Genetic disorder resulting in production of faulty HDL particles that cannot take up cholesterol from cells
High risk for developing cardiovascular disease

16. Properties of Plasma Lipoproteins
Property
Chylomicron
VLDL
IDL
LDL
HDL
Density (g/mL)
<1.006
Lipids (%) 98 92 85 79 50
Protein (%) 2 8 15 21

17. Lipids (%) in Plasma Lipoproteins
Chylomicron
VLDL
IDL
LDL
HDL
Cholesterol 9 22 35 47 19
Triglyceride 82 52 20 3
Phospholipid 7 18 23 28

18. Cardiovascular disease (CVD)
General term for all diseases of the heart and blood vessels
Atherosclerosis is the main cause of CVD
Atherosclerosis leads to blockage of blood supply to the heart, damage occurs (coronary heart disease, CHD)
Cardio = heart
Vascular = blood vessels

19. Lipoproteins and cardiovascular disease (CVD) risk
LDL is positively associated with CVD
HDL is negatively associated with CVD

20. LDL and atherosclerosis

21. Recommended blood lipids
Total cholesterol: <200 mg/dL
LDL cholesterol: <130 mg/dL
HDL cholesterol: >35 mg/dL
Triglycerides: <200 mg/dL