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

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

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

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

The Origins & Major Functions of Lipoproteins

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

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

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

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

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)

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

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

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

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

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

Properties of Plasma Lipoproteins Property Chylomicron VLDL IDL LDL HDL Density (g/mL) <1.006 1.006-1.019 1.019-1.063 1.063-1.21 Lipids (%) 98 92 85 79 50 Protein (%) 2 8 15 21

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

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

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

LDL and atherosclerosis

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