High cholesterol as a risk factor for stroke

Background
Lipids or fats are found in our blood stream. There are different kinds of lipids that affect stroke risk. We will begin with cholesterol.
Cholesterol is made in the liver and is found in certain foods. While it is essential for the smooth working of the body, too much cholesterol can lead to furring up of the blood vessel walls making them more brittle and increase the likelihood of blockages.
Gender, age, general health and a family history of high cholesterol can affect your cholesterol levels. But for most people, high cholesterol is caused by eating food containing too much saturated fat (for example in beef or cheese) and not enough food containing unsaturated fats (such as nuts and avocadoes). Being overweight, being less active, drinking too much alcohol and smoking can all contribute to high cholesterol levels.
What is a healthy level of cholesterol?1
- Total cholesterol levels should be below 5.00mmol/L, with non-HDL (LDL) levels below 4.00mmol/L.
- Levels of HDL cholesterol should be above 1.0mmol/L for men or above 1.2mmol/L for women.
Cholesterol and stoke
Most research suggests that there is a direct link between cholesterol levels and stroke risk. High levels of LDL cholesterol (bad cholesterol) raises stroke risk, while HDL cholesterol (good cholesterol) may be beneficial because it helps remove excess cholesterol from the system.
Haemorrhagic stroke is more prevalent at lower cholesterol levels, while high cholesterol seems to raise the risk of certain types of stroke more than others.2,3
Some research suggests that having high blood pressure as well as high levels of cholesterol increases stroke risk further.4
Other lipids and stroke
Triglycerides are another type of fat found in the blood stream which thought to increase the risk of stroke.5 Triglycerides are made in our liver but high levels of triglycerides are related to diets with sugary drinks and snacks for example.
High levels of lipoprotein (a) increase the risk of stroke and appear to be an inherited or a genetic condition. It can also increase the risk of the thickening and hardening of the walls of arteries and it may trigger blockage of the arteries and cause clots. The levels of lipoprotein (a) vary widely between people, but there is a two to threefold higher concentration in people of African descent than in other populations. Research is ongoing for treatments.
Testing for lipids
Testing for cholesterol and triglycerides can be done as a preventative measure and after someone has had a stroke to reduce the chance of them having a second stroke.
Lipoprotein (a) levels in our blood stream can be measured but few countries screen for this lipid.6
Cholesterol and stroke: Key points
High levels of lipids including cholesterol can increase the risk for stroke.
If cholesterol levels cannot be controlled through changes in lifestyle such as diet low in saturated fats such as nuts and avocadoes, it is usually treated with statins. In several trails statins were shown to reduce stroke risk by between 11% and 40% and higher doses appear to reduce the risk more.7 Similarly, maintaining a healthy weight is associated with lower cholesterol levels. People who are overweight or who have obesity may only need to lose 5 to 10% of their starting weight to reduce their “bad cholesterol” and increase their “good cholesterol”. 8
References
- Scott M Grundy, Neil J Stone, Alison L Bailey, Craig Beam, Kim K Birtcher et al. 2018 AHA/ACC/AACVPR/AAPA/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA Guideline on the Management of Blood Cholesterol: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. J Am Coll Cardiol. 2019 Jun 25;73(24):e285-e350. https://doi.org/10.1016/j.jacc.2018.11.003
- Shadi Yaghi, Mitchell S V Elkind. Lipids and Cerebrovascular Disease: Research and Practice. Stroke. 2015. Nov;46(11):3322-8. https://doi.org/10.1161/STROKEAHA.115.011164
- Aladeen Alloubani, Refat Nimer, Rama Samara. Relationship between Hyperlipidemia, Cardiovascular Disease and Stroke: A Systematic Review. Curr Cardiol Rev. 2021. Dec 28; 17(6): e051121189015. https://doi.org/10.2174/1573403X16999201210200342
- C Wang, Z Du, N Ye. et al. Hyperlipidemia and hypertension have synergistic interaction on ischemic stroke: insights from a general population survey in China. BMC Cardiovasc Disord. 2022. 22(47). https://doi.org/10.1186/s12872-022-02491-2
- N Akhtar, R Singh, S Kamran et al. Association between serum triglycerides and stroke type, severity, and prognosis. Analysis in 6558 patients. BMC Neurol. 2024. 24:(88). https://doi.org/10.1186/s12883-024-03572-9
- Alberico L Catapano, Magdalena Daccord, Elaine Damato, Steve E Humphries, R Dermot G Neely, Børge G Nordestgaard, Michele Pistollato, Elisabeth Steinhagen-Thiessen. How should public health recommendations address Lp(a) measurement, a causative risk factor for cardiovascular disease (CVD)? Atherosclerosis. 2022 May:349:136-143. https://doi.org/10.1016/j.atherosclerosis.2022.02.013
- T. Wein and D Gladstone on behalf of the Canadian Stroke Best Practice Recommendations Prevention of Stroke Writing Group. Canadian Stroke Best Practice Recommendations. Prevention of Stroke Evidence Tables Lipid Management. 2017. https://www.heartandstroke.ca/-/media/1-stroke-best-practices/prevention-of-stroke/2016_csbpr-prevention-evidence-table-4_lipid-management_october-27-2017.ashx?rev=977001a920944d5ebee34e2da88d9804
- Harvard Health. Controlling your weight is key to lowering stroke risk. 2020. https://www.health.harvard.edu/heart-health/controlling-your-weight-is-key-to-lowering-stroke-risk