Cholesterol is a fat chemical made by the cells of your body. Different cells of the body make cholesterol but liver cells make about a quarter of the total. Everyone requires some cholesterol to keep themselves healthy.
Cholesterol is carried in the blood by lipoprotein particles. When low-density lipoproteins (LDL cholesterol) carry cholesterol, it is referred to as ‘bad’ cholesterol. In your blood, higher levels of LDL cholesterol cause an increased risk of cardiovascular disease.
However, some cholesterol is also carried by high-density lipoproteins (HDL cholesterol) in your blood. HDL cholesterol can be regarded as ‘good’ cholesterol. Moreover, its higher levels help to prevent cardiovascular disease.
Cholesterol levels are very important but must be considered in an overall assessment of your cardiovascular disease risk. The following levels of blood cholesterol are generally regarded as desirable;
- Total cholesterol (TChol): 5.0 mmol/L or less. However, around 2 in 3 adults in the UK have a TChol level of 5.0 mmol/L or above.
- LDL cholesterol: 3.0 mmol/L or less.
- HDL cholesterol: 1.2 mmol/L or more.
- TChol/HDL ratio: 4.5 or less. That is, TChol divided by your HDL cholesterol. That reflects the fact that for any given TChol level, the more HDL, the better.
Factors affecting the blood cholesterol level
To an extent, blood cholesterol level can differ on the basis of your diet. But, different people who have the same diet can have different blood cholesterol levels. In general, however, if you consume less fatty food your cholesterol level is probably to go down.
In some people, there is another condition of high cholesterol level. For instance, obesity, an underactive thyroid gland, some rare kidney and liver disorders and drinking a lot of alcohol can raise the blood cholesterol level. Hyperlipidemia means too much lipid (mainly cholesterol) in your bloodstream.
In some cases, a very high cholesterol level runs in the family. This is due to a genetic problem. One of its examples is called familial hypercholesterolemia.
In general, the higher the LDL level, the greater the risk to health. Therefore, a blood test only measuring total cholesterol may be confusing. High total cholesterol may be caused by a high HDL cholesterol level and is hence healthy. Thus, it is important to know the separate LDL and HDL cholesterol levels.
What causes high cholesterol?
Everyone has some risk of developing small fatty lumps inside the lining of blood vessels. This may cause one or more cardiovascular diseases. However, there are some situations which can increase the risk. These include;
Lifestyle risk factors can be prevented or changed;
- Lack of physical activity (a sedentary lifestyle).
- An unhealthy diet – including eating too much salt.
- Excess alcohol.
Treatable or partly treatable risk factors;
- High blood pressure (hypertension).
- High cholesterol blood level. However, only LDL cholesterol is a risk factor and HDL cholesterol is not harmful to your body.
- High triglyceride blood level.
- Kidney diseases which affect kidney function.
Fixed risk factors which you cannot change;
- A strong family history can be a fixed risk factor. It means if you have a father or brother who developed stroke or heart disease before they were 55, or disease in a mother or sister before they were 65.
- Being male.
- Early menopause in women.
- People are more likely to develop atheroma as they get older.
- Ethnic group. For instance, individuals who live in the UK whose family came from Pakistan, Bangladesh, India, or Sri Lanka have an increased risk.
Changing your diet plan from an unhealthy diet to a healthy diet can decrease your LDL cholesterol level. However, in case of fixed risk factor, there is a need to make extra effort to tackle lifestyle risk factors which can be changed.