This page helps you to understand blood test results for cholesterol and gives you the reference range to determine if your lab test results mean that you have high cholesterol, low cholesterol or normal cholesterol levels.
We outline the risk factors associated with both raised cholesterol and lower cholesterol levels.
Reference Ranges for Total Cholesterol:
|US Conventional Units||mg/dl||<=199||200-239||>=240|
|Standard International Units||mmol/L||<=5.2||5.3-6.2||>=6.3|
What is Cholesterol
Cholesterol is a waxy substance that is found in the fats (lipids) in your blood. It is produced in the body by the liver and also consumed in the diet in foods of animal origin such as meat, eggs, fish and dairy .
Cholesterol travels through your bloodstream in small packages called lipoproteins. These packages are made of fat (lipid) on the inside and proteins on the outside .
Total cholesterol is the sum of the amount of low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) and other fatty substances (triglycerides) in your blood .
Low-density lipoprotein (LDL) cholesterol is also known as the “bad” cholesterol. Too much of it in your blood causes the build-up of fatty deposits (plaques) in your arteries (atherosclerosis), which reduces blood flow. These plaques sometimes rupture and can lead to a heart attack or stroke .
High-density lipoprotein (HDL) cholesterol is also known as the “good” cholesterol because it helps carry away LDL cholesterol, thus keeping arteries open and your blood flowing more freely. Unlike the other makers in the lipid profile, higher values of HDL cholesterol are favorable .
To calculate your Cholesterol Ratio, divide your high-density lipoprotein (HDL, or “good”) cholesterol number into your total cholesterol number. An optimal ratio is less than 3.5-to-1. A higher ratio means a higher risk of heart disease .
Function of Cholesterol
Cholesterol has many functions in the body including hormone production, digestion and maintaining healthy cell structures
Hormone Production – Cholesterol is stored in the adrenal glands, ovaries and the testes and is converted to steroid hormones which have a role to play in key functions such as digestion, bone health, mental well-being and maintaining a healthy weight.
Digestion – Cholesterol is used to help the liver create bile which aids us in digesting the food that we eat, particularly fats. When the fat goes undigested it can get into the bloodstream and cause additional problems such as heart attacks and heart disease.
Cell Structure – Cholesterol is a structural component of cells. Cholesterol along with polar lipids make up the structure of each and every cell in our bodies. Cholesterol provides a protective barrier, and when the amount of cholesterol increases or decreases the cells are affected, which can impact our ability to produce energy.
Risk factors associated with Cholesterol
Higher levels of LDL cholesterol are associated with an increased risk of coronary heart disease. Conversely, higher levels of HDL cholesterol in your blood are related to lower risk levels .
Coronary heart disease is a condition in which plaque builds up inside the coronary arteries. Plaque is made up of cholesterol, fat, calcium, and other substances found in the blood. When plaque builds up in the arteries, the condition is called atherosclerosis .
Genetic factors are highly correlated with the risk of heart disease, but you can still reduce your risk by making lifestyle changes to protect your heart .
Notable variations by demographic group
Genome-wide association studies (GWAS) have identified a number of single-nucleotide polymorphisms (SNPs) associated with higher lipid levels in populations of European descent. SNP’s relating to higher lipid levels can also occur in other ethnic groups, which may help in identifying subgroups with a high risk for an unfavourable lipid profile .
Cholesterol levels often increase with age, and it is important to view results in the context of overall health. For example people with heart disease or diabetes need to be particularly mindful of keeping their levels of LDL cholesterol and Triglycerides low. Where there is a pre-existing condition you should consult with your doctor for appropriate reference ranges for these markers.
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Diet to improve Cholesterol
A healthy balanced diet can help reduce levels of LDL cholesterol and ApoB whilst also increasing HDL cholesterol, thereby lowering your risk of heart disease .
- Eat plenty of fibre to help lower your risk of heart disease and type 2 diabetes. Adults should aim for at least 30g of fibre a day. Your diet should include a mix of sources of fibre. Good sources of fibre include: fruit and vegetables, potatoes with their skins on, porridge oats, pulses such as beans and lentils, and nuts and seeds .
- Reduce your total fat intake, especially saturated fat which raises cholesterol. Foods high in saturated fat include butter, cheese, fatty meat and processed foods like biscuits and cakes . Replace foods high in saturated fat with small amounts of unsaturated fats, which are good for cholesterol levels. Foods high in unsaturated fat include oily fish, olive oil, nuts and seeds .
- Grilling, steaming or poaching your food instead of roasting or frying means you don’t need to add fat when you’re cooking .
- Reduce your alcohol intake. Regularly drinking alcohol can lead to weight gain, high blood pressure, and a higher risk of heart disease .
Supplements for Cholesterol
Numerous supplements have been shown to be effective at lowering bad cholesterol including, plant stanols, plant sterols, green tea extract and whey protein. Niacin has been shown to have the dual benefit of lowering LDL cholesterol while raising levels of HDL cholesterol .
Exercise to improve Cholesterol
An active lifestyle can reduce your risk of developing heart disease by lowering your blood pressure, weight, cholesterol and Apo B levels.
Sleep for Cholesterol
A study by the American Sleep Association found that the genes responsible for cholesterol transportation are not as active in someone who has suffered with sleep deprivation, leading to higher cholesterol levels. These finding are in line with a widespread acceptance that higher risk of cardiovascular disease is seen in those with sleep deprivation.
Other ways to improve Cholesterol
If you are a smoker, stopping is the biggest step you can take to reduce your risk of developing heart disease. Smokers are nearly twice as likely to have a heart attack as people who have never smoked. But within a year of stopping smoking, your risk of heart attack falls to about half that of a smoker .
damage the lining of your arteries, leading to a build-up of cholesterol deposits, and can also lower HDL cholesterol
- increase your blood pressure and heart rate, meaning your heart has to work harder
- reduce the amount of oxygen your blood can carry to your heart and body
- make your blood more likely to clot