Cholesterol is a type of fat molecule called a lipid. It's used by our body in a multitude of ways, helping to produce vitamin D, bile acid and hormones like testosterone and oestrogen. Cholesterol has another key role in the body, acting like a glue which holds the outermost part of our cells, called the cell membrane, together.
When people talk about having high or low cholesterol, they're usually referring to amount of lipoproteins in the blood. Lipoproteins are molecules that transport cholesterol around the body.
There are two main types of lipoprotein circulating around in your bloodstream, LDL and HDL. Having too much or too little of these lipoproteins in your blood can dramatically affect your health.
HDL - High Density Lipoprotein
This is sometimes called good cholesterol. HDL acts like a delivery driver, picking up the 'bad' cholesterol molecules and moving them to the liver where they can be processed and broken down. Your diet and genetics can affect how much HDL you produce. Taking certain prescription medicines such as statins and niacin can also increase the amount of HDL in your blood.
LDL – Low Density Lipoprotein
LDL is often referred to as the bad cholesterol. LDL picks up cholesterol molecules and carries them directly to your arteries. Over time, fatty deposits called plaques can form in your arteries, narrowing them and preventing blood from flowing through them. This can cause blood clots and atherosclerosis, a disease which increases your risk of having a heart attack or stroke.
Having high levels of LDL in your blood is increasingly common, affecting around 60% of people in the UK. Most people don't realise that they have high cholesterol until they visit their doctor.Lowering your cholesterol can often be achieved by changing your diet. Eating less saturated fat while increasing the amount of soluble fibre you consume can lower LDL. Exercising more and quitting smoking will also help. To treat high cholesterol, you may be advised to take statins or other medication.
The overall amount of cholesterol in your blood is known as your total cholesterol or serum cholesterol. This number includes HDL, LDL and some other fats. A Total Cholesterol test is often used to measure your risk of developing heart disease.
Getting the Ratio Right
The ratio of total cholesterol to HDL cholesterol in the blood stream is sometimes used as a measure of health. It's easy to understand and a reliable indicator of how likely you are to develop complications like heart disease and stroke. This ratio is calculated by taking your total cholesterol and dividing it by your HGDL cholesterol. A ratio of under 4 is considered healthy while a ratio of more than 6 puts you are risk of developing heart disease. You can find out your cholesterol here.