Many of us are aware that evidence strongly indicates that high cholesterol can increase the risk of heart disease, strokes and mini strokes (TIA’s), peripheral arterial disease and narrowing of the arteries (atherosclerosis) but what exactly is cholesterol, and what do those numbers mean when we have our cholesterol checked?

What is cholesterol?

Cholesterol is a fatty substance known as a lipid found naturally within the body’s cells and is vital for the normal functioning of the body. It's mainly made by the liver, but can also be found in some foods. Cholesterol is carried in your blood by proteins. When the 2 combine, they are called lipoproteins.


Your blood carries cholesterol around your body on proteins known as high density lipoproteins (HDL) or ‘good cholesterol’, and low density lipoproteins (LDL) – ‘bad cholesterol’. HDL cholesterol helps your body by carrying cholesterol away from the cells and back to the liver where it is either broken down or passed out of the body as a waste product,  LDL cholesterol carries cholesterol to the cells that need it, but if there is too much cholesterol for the cells to use, it can build up in the artery walls and can cause blood vessels to become narrowed or blocked.

Anyone can get high cholesterol, and it can be caused and affected by many different things including:-

  • eating a lot of saturated fat
  • smoking
  • not being active enough
  • having too much body fat, especially around your middle
  • getting older
  • if you are male or female
  • ethnic background
  • Familial Hypercholesterolaemia (FH) and other inherited diseases.


When should I get tested?

·       Every 5 years if you are between the ages of 40 and 75

·       Every 12 months if you are on cholesterol lowering medication

·       Any child of a parent with inherited high cholesterol (FH) by the age of 10

·       First degree relatives of a person with FH - on being told of the risk

The NHS will provide you with a free cholesterol test if you fall into any of the above groups, speak to your Doctor or Practice Nurse about arranging your cholesterol test. 


Know Your Numbers

Total Cholesterol (TC)
This is the amount of cholesterol in your blood
·       Ideally it should be 5 mmol/L* or less

This is your total cholesterol minus your HDL-cholesterol (good cholesterol) and is the sum of all the "bad" cholesterols added together (including LDL cholesterol)
·       Ideally it should be 4 mmol/L* or less
·       LDL-Cholesterol (LDL-C)
This is the amount of bad cholesterol
·       Ideally it should be 3 mmol/L* or less

HDL-Cholesterol (HDL-C)
This is the amount of good cholesterol
·       Ideally it should be over 1 mmol/L* (men) and over 1.2 mmol/L* (women).

TC:HDL ratio 
This is the TC figure divided by the HDL-C figure. 
·       A ratio above 6 is considered high risk - the lower this figure the better.

Triglyceride (TG) 
This represent your body's ability to clear fat from the blood after a meal.  
·       Ideally it should be less than 1.7 mmol/L* on a fasting sample or less than 2.3 mmol/L on a non-fasting sample) ​

This table was re-produced using information taken from Heart UK The Cholesterol Charity

*Cholesterol is measured in millimoles per litre (mmol/L)

If your cholesterol is very high and if lifestyle changes are not enough, your doctor might suggest controlling it with medication.  Whether or not you need to take cholesterol-lowering medicine depends on your overall risk of cardiovascular disease.

Cholesterol-lowering medicines such as statins are prescribed for people who are at greatest overall risk of cardiovascular disease.


Further sources of information

Heart UK - Cholesterol Facts

NHS UK - Cholesterol

British Heart Foundation - How to Reduce Cholesterol diet


Written with the kind permission of Alison Lambert (Occupational Health Nurse) at Workfit

Knowledge Bank