First of all let’s just cover what cholesterol is.
Cholesterol is a waxy substance known as a large lipid molecule which is produced and released into your bloodstream by cells in your liver. It is also found in certain foods.
Cholesterol cannot be used by your body for energy, instead it is used for the production of steroid hormones, the synthesis of bile acids and vitamin D. Your liver actually produces the majority of your cholesterol needs, with only around 20% needing to come from your diet.
Because cholesterol is a lipid (fat) it is not water-soluble therefore it will not mix with blood. Instead your body uses little transporters called lipoproteins.
Very low-density lipoproteins (VLDL)
These are synthesised by your liver and carry cholesterol and triglycerides (another type of fat). Their job is to transport triglycerides into adipose tissue (fat storage).
Low-density lipoproteins (LDL)
These are formed from VLDLs once the VLDLs have unloaded most of their triglycerides into fat storage. LDLs deposit the cholesterol they carry on the artery walls and begin a process called atherosclerosis.
High-density lipoproteins (HDL)
HDLs remove cholesterol from your blood stream and your artery walls, which is why they are often known as good cholesterol. Unlike the former two, which are known as bad cholesterol.
So is cholesterol good or bad?
The answer is BOTH. Cholesterol is essential to life but if we have too much of it in our blood then it can deposit on our artery walls and lead to cardiovascular disease.
When you have your blood cholesterol checked you are usually given a score.
Total cholesterol score = HDL + LDL + Triglycerides
In the UK the desirable upper limit of total cholesterol is 5.2mmol/dL. If levels are above this then lifestyle changes, such as increasing your activity levels are recommended.