Cholesterol is a waxy, fat-like substance used by your body for many essential functions including producing hormones and vitamin D. Your body actually produces as much cholesterol as it needs but can also absorb small amounts from food. When we talk about cholesterol in terms of heart health, we are really talking about molecules called lipoproteins, which are like containers for cholesterol that allow it to travel around the body.
HDL – the ‘good’ cholesterol
Two important types of lipoprotein are low-density lipoprotein (LDL) and high-density lipoprotein (HDL). Around 60–70% of total blood lipoproteins are LDL and it transports cholesterol particles around your body. HDL is slightly different – it helps to collect excess cholesterol and transports it back to the liver to be used or excreted. HDL cholesterol (HDL-C) can also reduce inflammation and help repair the inside of blood vessels.
High levels of LDL cholesterol (LDL-C) are associated with the build-up of plaque on artery walls and increased risk of heart disease. In contrast, high levels of HDL-C are associated with reduced risk of heart disease and low levels are a risk factor for heart disease.
Low HDL-C is associated with insulin resistance (also called pre-diabetes), type 2 diabetes, obesity, a high carbohydrate diet, smoking, and inactivity. However, low HDL-C can also be caused by underlying illnesses or genetic conditions.
A low level of HDL-C is one of the risk factors for metabolic syndrome.
How is HDL-C measured?
A doctor may ask you to do a cholesterol test, or lipid panel, and the results are interpreted as follows.
HDL-C levels greater than 60 milligrams per decilitre (mg/dL) are high, which is good.
HDL-C levels less than 40 mg/dL are low, which is not good and associated with a higher risk of cardiovascular disease.
How is low HDL-C treated?
If your HDL-C is low, you can try to increase it by doing aerobic exercise for 30-60 mins 5 days a week, quitting smoking and achieving and maintaining a healthy bodyweight. Despite what many people think, dietary cholesterol does not have much of an effect on blood cholesterol levels, either LDL or HDL. High cholesterol foods actually include many very nutritious foods such as grass-fed beef, eggs and sardines, so don’t be afraid to include these in your diet in moderation! Medications are also available to increase HDL-C in people who do not respond to lifestyle changes.
You should always talk to your doctor before beginning an exercise programme or radically changing your diet.
References
Zhou L, et al. Mol Med Rep. 2015 Sep;12(3):4015-4021.
Kopin, L., & Lowenstein, C. J. (2017). Dyslipidemia. Annals of Internal Medicine, 167(11), ITC81.