Cholesterol - Sarah

What is cholesterol?

1. A core of insoluble lipid (cholesterol) surrounded by an external polar coat of protein. This transports the cholesterol around the body
2. The amount of protein to cholesterol determines the ‘goodness’ of the cholesterol.
3. There are 4 types of lipoproteins which carry around cholesterol

a. Chylomicron

• Highest in TAGs (Triacylglycerols) content
• Transports TAGs and cholesteral to adipose tissue after meal.
• Removed by liver

b. VLDL (very low density lipoprotein)

• Synthesized by liver (56%TAG)
• Transport TAG from the liver to the tissues in between meals.
• Either returned to liver or converted to LDL

c. LDL (low density lipoprotein)

• Carry cholesterol to the tissues (adrenal glands or liver)
• Chief carrier of cholesterol
• Long lifetime in blood
• Involved in development of atherosclerosis
• Want low levels

d. HDL

• Protein rich particles containing little cholesterol
• Transport cholesterol away from tissues
• Protect arteries from high cholesterol
• Synthesised in the intestines and liver
• Want high levels

What is high cholesterol?

• If your cholesterol level is 6.5mmol/L or greater your chances of heart disease are 4 times greater than that of a person with a cholesterol level of 4mmol/L.
• Changing dietary intake can alter your cholesterol by approximately 10%

What type of foods are low in bad cholesterol (LDL) and high in good cholesterol (HDL)?

• Dietary cholesterol

1. Brain, liver, eggs, prawns, lean meat• Intake has little effect on lipoprotein levels.

• Soluble fibre
• Oatbran, fruit, vegetables
• Can decrease total cholesterol by aiding cholesterol excretion.
  

1. Saturated fat

• Butter, cream, meat fat, pastry
• And trans fatty acids – hydrogenation of oils to fats eg. Margarines
• Both increase LDL

1. Carbohydrates

• Bread, pasta, starchy vegetables, rice
• Decrease LDL
• However if carbohydrate is high in sucrose or fructose and low in dietary fibre
• VLDL may increase, and HDL may decrease
  

1. Monounsaturated fatty acids

• E.g. olive oil, canola oil, avocado, almonds, macadamias
• Decrease LDL
• No rise in VLDL
• No rise in HDL
  

1. Polyunsaturated fatty acids

• Sunflower oil, walnuts
• Decrease LDL
• No rise in VLDL
• LDL susceptible to oxidation high intake may decrease HDL
• Sardine, salmon
• Decrease VLDL
  

1. The Mediterranean diet

• Rich in omega-3 – found in fish – reduces risk of CV mortality
• Low in saturated fats
• Decrease in total serum cholesterol and LDL, little change in HDL
  

Recommended fat intake
• Saturated fatty acids should provide 10% of dietary energy
• Cis-monosaturated acids (mainly olein acid) should provide approx. 12% of dietary energy.
• Cis-polyunsaturated acids should provide 6% of dietary energy.
• Total fat intake should ne no more than 35% of total dietary energy and restricted to 30% is desirable.

SO what does this mean for Roger, he should
o Decrease red meat
o Increase fruits, vegetables, beans, pasta, bread
o Decrease sugary drinks
o Increase vegetable (including olive oil) and fish oil
o Decrease animal fat
o Cholesterol – decrease meat and eggs (maybe?)
o Eat less salt.
o Limit eggs to 1/day

Some recent research
• Has found that cholesterol in the diet has much less of an effect than saturated fats in the diet. So food like eggs even though they are relatively high in cholesterol may not be bad. They also have unsaturated fat which is good for lowering LDL in the blood stream. However, if you already have high cholesterol, this is different and may actually raise the ‘bad’ (LDL) cholesterol levels.


References
• Eat Fat Get Thin lecture notes, week 3, semester 1, 2008
• Kumar and Clarke
• http://www.csiro.au/resources/CholesterolFacts.html
• http://www.abc.net.au/health/healthyliving/stories/2008/05/27/2235487.htm
• http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Cholesterol_explained?OpenDocument