Cholesterol Flashcards
Cholesterol
Cholesterol is an important compound for cell structure and function. Beneficial properties are often overlooked because of negative perceptions around cardiovascular disease risk.
Cholesterol: Functions
• Cholesterol is essential for the synthesis or action of:
– Vitamin D and calcium metabolism.
– Cortisol and related hormones.
– Aldosterone for mineral and fluid balance.
– Sex hormones oestrogen, progesterone and testosterone.
– Bile salts and acids needed for digestion.
– Membrane integrity , especially in the
– Lipoproteins , needed for triglyceride transport.
Cholesterol: Digestion
A diet rich in triglycerides stimulates cholesterol synthesis in the liver and small intestine.
• It is excreted in the stool intact, mostly as bile products.
• The excretion is increased by absorption onto non-digestible carbohydrates (fibre).
• Gut bacteria from healthy microbiomes metabolise cholesterol = less reabsorption.
• Dietary cholesterol does not significantly affect plasma cholesterol levels in most people as they are primarily influenced by genetic and nutritional factors.
LDL and HDL
Doctors and other health officials often refer to cholesterol as ‘good’ and ‘bad’, especially in reference to heart
• LDL and HDL cholesterol are in fact carriers . Cholesterol sits within these lipoproteins to be transported to wherever needed.
• A lot of other substances are carried within them including CoQ10, beta carotene and vitamin E.
• LDL (low density) takes cholesterol from the liver to cells.
• VLDL (very low density) takes triglycerides to cells.
• HDL (high density) collects cholesterol from cells to transport back to the liver.
Cholesterol: Government guidelines
Governments have led us to believe that saturated fat and cholesterol simply clog up arteries and cause heart attacks.
• This led to a global cholesterol lowering industry, with around 200 million people taking statins.
• In 2009, a study found that ‘bad’ cholesterol was lower in people with heart disease.
• Over a period of 10 years the percentage of men aged 65-74 with high cholesterol dropped from 87 to 54, whereas CHD remained at 20%.
• In 2004, the definition of low plasma cholesterol dropped from below 6.5 mmol / L to below 5 mmol / L.
Increases in cholesterol
Increases in cholesterol may indicate an increased demand for cholesterol’s anti inflammatory function or an increased need for cholesterol to repair membranes, make hormones, etc.
• Atherosclerosis requires LDL cholesterol to deposit in the arterial wall and become oxidised.
• Atherosclerosis is an inflammatory disease. In the absence of inflammation or injury to the endothelium, cholesterol does not deposit.
• There are varying sizes of LDL cholesterol. Measuring particle size rather than total cholesterol is a better health indicator.
Cardiovascular Markers: LDL particle size
LDL particle size: people whose LDL particles are predominantly small and dense have a threefold greater risk of coronary artery disease, whereas the large and fluffy type may be protective.
Cardiovascular Markers: HDL particle size
HDL particle size: larger HDL particles are more effective at removing cholesterol from the blood. Larger particles better exert anti inflammatory and anti thrombotic effects, as well as promoting nitric oxide production in endothelial cells.
Cardiovascular Markers: Lipoprotein (a)
Lipoprotein (a) lipoprotein (a) is a blood clotting agent. It appears to be a key genetic risk factor in coronary artery disease. Higher levels are associated with greater risk.
Cardiovascular Markers: Lp-PLA2
Lp PLA 2 an enzyme that plays a role in endothelial inflammation and atherosclerosis.
Cardiovascular Markers: Fibrinogen
Fibrinogen - raised levels are a risk factor for clot formation
Cardiovascular Markers: C-reactive protein
C-reactive protein inflammatory marker associated with CVD.
Cardiovascular Markers: Lipid peroxides
Lipid peroxides raised levels reflect oxidative damage to membranes.
Phospholipids
Phospholipids are the structural basis of all cell membranes. Different types of phospholipids perform roles in cellular function, such as insulin signalling.
• Phosphatides contain glycerol, two long chain fatty acids, a phosphate group, and either inositol, choline or serine.
• Phosphatidylcholine predominant phospholipid in the body.
• Lecithin synthesised by the liver and plays a role in emulsification (fat digestion). Lecithin increases the solubility of cholesterol and helps improve cognitive function.
Phospholipids: Phosphatides
• Phosphatides contain glycerol, two long chain fatty acids, a phosphate group, and either inositol, choline or serine.
