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

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

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

Liver 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

1.006-

1.019

1.019-

1.063

1.063-

1.21

Lipids (%)

98 92 85 79 50

Protein (%)

2 8 15 21 50

Lipids (%) in Plasma Lipoproteins

Lipid Chylomicron

VLDL IDL LDL HDL

Cholesterol 9 22 35 47 19

Triglyceride 82 52 20 9 3

Phospholipid

7 18 20 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