WHAT ARE LIPIDS & FATS? 

Lipids are types of "blood fats".  They are insoluble in water or blood so are carried around in "ships" - called lipoproteins.  They are really important for the functioning of the body.   Lipids include fatty acids, cholesterol and essential fat soluble vitamins.  

Fatty acids are high density sources of fuel and are a source of energy for cells.  3 fatty acids form Triglycerides (TGs). The other form of energy is glucose.  

Cholesterol is a lipid predominantly made in the liver.  A small amount comes from diet. It is needed in every cell in the body - it is essential for:

• cell structure and function
• hormone synthesis e.g. oestrogen, testosterone, cortisol, Vit D3
• creation of bile acids which help us absorb fat and fat soluble essential vitamins (A,D, E and K)
  

Adipose tissue = commonly known as 'body fat', is a store of energy as lipids (mainly triglycerides) ready to be mobilised for energy. Too much adipose tissue around organs can affect how they function and worsen our metabolic health. 

FURTHER INFORMATION ON STATINS

In 1955, Ansel Keys led the way on the 'diet heart hypothesis', suggesting that very simply dietary cholesterol increases cardiovascular disease and that we need to reduce cholesterol to reduce risk.  This led  to a worldwide use of statins.  This video "Statin nation" discusses some limitations and questions this theory.  However, while our understanding of risk factors is constantly changing, NICE guidance suggests statins still have a role to play.  

THE GOOD AND BAD CHOLESTEROL

The liver makes low density (LDL) and high density (HDL) lipoproteins (ships).  LDL known as "bad cholesterol" carries TGs (Triglycerides) and cholesterol towards cells and arteries and HDL (high density), or "good cholesterol", carries TGs and cholesterol back to the liver for hormone synthesis, recycling or disposal- but it is all the same 'cholesterol'!.  These LDL/HDLs represent our long term lifestyle habits.  

The dietary fat we eat in the gut forms a different ship called a chylomicron, made mainly from TGs.  This lipid level in our blood will rise and fall after meals (so if we are measuring your TGs in your blood profile, we may ask for a fasting test).  

"The bad cholesterol" we talk about includes this dietary chylomicrons and other lipoproteins as well as LDL, classified together as "non HDL cholesterol" (reference the guidleines table). 

Non HDL cholesterol has been shown to be associated with the development of atherosclerosis, contributing to plaques and heart disease.  Reducing non-HDL cholesterol is therefore thought to improve your cardiovascular risk.  However, what we don't fully understand is whether the absolute number is important, or whether damage e.g. from inflammation, smoking, high sugar levels affects the way this bad cholesterol behaves.  

FURTHER INFO ON LIPID PROFILE IN LOW CARB DIETS 

In this video below, Dr David Unwin describes some positive changes in your lipid profile you may expect to see on a lower carb diet.

There are a very few cases of 'hyper responders' where the lipid profile might change in a different way.  These patients should have further discussions with their GP.