Flashcards in Nutrition Module 11: CVD - Lipoproteins Deck (55)
Where do most of the FAs in the body come from?
What are the 3 atherogenic lipoproteins?
1. Chylomicron remnants
3. VLDL remnants
What are the 3 non-atherogenic lipoproteins?
What do people who cannot produce chylomicrons due to genetic defects usually suffer from? Why? Treatment?
Neuropathy because neurons lack vitamin E
Treatment: VE injections or oral doses that are thousand fold higher than normal
Describe the route of chylomicrons (5 stops)
3. Adipose tissue
4. Hepatic artery
How fast are chylomicrons cleared from the bloodstream? What determines the rate of clearance?
Genetics and dietary habits (high/low-fat)
How does the amount of fat eaten in a typical american meal affect the rate of clearance of chylomycrons? How does this affect atherosclerosis risks?
The amount of fat saturates the clearance pathway which prolongs their circulation causing increased atherosclerosis risks
What is an independent risk factor of CVD?
Elevation of serum TAGs
What can high TAGs be caused by?
2. Lack of PA
3. High carbs
What 3 molecules do VLDLs transport?
3. Vitamin E
Which is faster: chylomicrons or VLDL TAG hydrolysis?
What is the main difference between chylomicron and VLDL remnants?
Chylomicron remnants are all cleared by receptor-mediated endocytosis vs only half of VLDL remnants are cleared like this
Which have longer half-lives: chylomicrons or VLDLs?
What is fatty liver? What is it caused by?
Chronic alcohol abuse impairs the liver from exporting excess TAGs via VLDLs = TAGs accumulate
What is the half-life of LDLs?
Which lipoproteins mediate the transport of cholesterol from arterial walls into the liver?
2 components of LDLs?
2. Vitamin E
What is cellular LDL cholesterol uptake regulated for?
To ensure adequate supply of cholesterol for the synthesis of membranes, hormones, and other critical compounds
What causes slowed LDL uptake?
Cells have enough cholesterol => fewer receptors are expressed especially on liver => LDL receptor down-regulation
How does dietary cholesterol intake affect the liver? What is the net effect?
Down-regulation of liver LDL receptors = high serum LDL = harder for liver to excrete as bile
Which cells have the highest LDL receptor activity?
Adrenal gland cells
Does the liver have to convert cholesterol into bile acids before it goes into bile?
What kinds of FAs can lower LDLs?
Polyunsaturated FAs (eg: omega-3 FAs)
What kinds of FAs can increase LDLs?
Saturated and trans FAs
What kinds of FAs have no effect on LDL levels?
What are the 4 factors that influence LDL levels?
2. Body weight
By what % can lifestyle changes reduce excessive LDL levels?
Other than polyunsaturated FAs, what 5 other foods can lower LDL levels?
1. Viscous dietary fiber
2. Soy protein
3. Plant stanols and sterols
What 4 foods are viscous fibers found in?
What 4 foods are plant stanols/sterols in?
3. Vegetable oils
What 4 foods are flavonoids in?
What are 2 viscous fibers?
What is a genetic factor that increases responsiveness to dietary cholesterol?
What kind of FA is myristic FA?
How does the raise in LDL due to saturated FAs compare to the lowering in LDL due to polyunsaturated FAs?
Raise is bigger
What are polyunsaturated FAs susceptible to? What does this cause?
Peroxidation making them more atherogenic and causing a chain of free radical and lipid hydroperoxide synthesis
Which lipoproteins are most susceptible to peroxidation? Why?
LDLs because of high polyunsaturated FA content
Why do some people with excess iron stores have increased CVD and cancer risks?
Because the generation of most toxic free radicals is catalyzed by free Fe Copper
What happens to oxidized LDLs?
They are no longer recognized by their normal receptors but bind to the scavenger receptor on macrophages (which become foam cells) and other cells to promote atherosclerosis
What can explain why antioxidants in fruits and veggies are more effective than those in supplements in preventing disease? 1 example?
Because antioxidants are interdependent and complimentary
Eg: ascorbic acid regenerates alpha-tocopherol inhibiting it from becoming a pro-oxidant
What are normal HDL levels?
40 and above in men
50 and above in women
What are the 4 main functions of HDLs?
1. Transfer apoC-II and apoE to chylomicrons and VLDLs to regulate them
2. Take up cholesterol and phospholipids from VLDLs and LDLs
3. Remove cholesterol from tissues
What are the 2 types of factors influencing HDL levels?
1. Constitutional factors
2. Lifestyle factors
What are the 3 constitutional factors of HDL levels?
1. Sex: women have higher levels
3. Hormonal status: decrease after menopause
What are the 3 lifestyle factors of HDL levels?
3. Alcohol (moderate intake increases HDL)
What are the primary prevention guidelines for CVD?
1. Maintain healthy weight
2. Sat fat intake below 10% of calories and low trans fats
3. Cholesterol intake below 300 mg/day
4. 2 servings of fish/week
6. Whole grains and high fiber foods
7. Salt intake below 6g aka 2300 mg
8. Alcohol limits to 2 a day for men and 1 for women
9. Limited foods/drinks with added sugar
What are the 2 FAs with the greatest cholesterol-raising potential? Foods high in these?
Myristic and palmitic acid in butter, whole milk, cream and high-fat cheeses
Which affect serum cholesterol levels the most: types of FAs consumed or dietary cholesterol?
Types of FAs
Which have more unsaturated FAs: liquid or solid fats?
Which lipoprotein delivers dietary cholesterol to the liver?
What are the most reversible vascular lesions?
Can carbs increase LDL levels?
What will usually raise LDL levels?
What can raise VLDL levels?
Reduced fat intake because VLDLs are needed to transport TAGs and cholesterol within the body