5 surprising things you didn't know about cholesterol
Think you know all there is to know about cholesterol? Think again!
We all know that high cholesterol is potentially dangerous as it is a major risk factor for heart disease, but here are 5 things that may surprise you about cholesterol.
1. Most of the cholesterol in your body doesn’t come from your diet
Cholesterol is important in the body for a number of processes including the production of many hormones, vitamin D and enzymes needed for digestion. 80% of the cholesterol in the body is produced by the liver and only about 20% of cholesterol in the body comes from the foods we eat. The liver produces more cholesterol when you eat a diet high in saturated and trans fats [i]. Trans fat increases the risk of heart disease by increasing LDL cholesterol levels and lowering the HDL cholesterol in the blood [ii].
2. Your hormones can affect your cholesterol levels
- PCOS: Hormonal imbalances in the body can negatively affect cholesterol levels. Polycystic ovary syndrome (PCOS) is a common condition that affects how a woman's ovaries work. The exact cause of PCOS is unknown but it is related to abnormal hormone levels in the body. Approximately 70% of women with PCOS have dyslipidemia, which causes high levels of triglycerides and low levels of high-density lipoprotein HDL (good cholesterol) [iii].
- Diabetes: According to Heart UK, having diabetes is considered a risk factor for heart and circulatory disease because those with diabetes are less efficient at processing cholesterol [iv]. Diabetes tends to lower 'good' cholesterol levels and raise triglyceride and 'bad' cholesterol levels, which increases the risk of heart disease and stroke [v].
- Hypothyroidism: An underactive thyroid (hypothyroidism), occurs when the thyroid gland does not produce enough of the thyroid hormones thyroxine (T4) and triiodothyronine (T3). Thyroid function significantly affects lipoprotein metabolism and hypothyroidism has an unfavourable effect on lipids as well as a number of other cardiovascular risk factors [vi]. If thyroid levels are low, the body isn’t able to break down and remove LDL cholesterol as efficiently as usual. LDL cholesterol can then build up in your blood.
3. Your brain is able to make its own cholesterol
The brain has a higher cholesterol content than any other organ. Most of the cholesterol is in the myelin sheaths that surround the axons of nerve cells, which aids the transmission of electrical impulses that control our thoughts, actions and movement. Because cholesterol is too big to cross the blood-brain barrier, the brain is able to make all of its own cholesterol on site [vii].
4. Taking steroids can affect cholesterol levels
One of the side effects of taking anabolic steroids or too much testosterone replacement is its impact on heart disease risk. We spoke with our sports and nutrition doctor Hamed Kamali and asked him to explain how steroids can affect cholesterol levels: “There are direct and indirect mechanisms by which steroid use can contribute to the development of heart disease. Anabolic steroids can cause abnormal cholesterol, increasing LDL levels and decreasing good HDL cholesterol levels. Not only is it the unfavourable movement of HDL and LDL that is important but how this affects the ratio of total cholesterol to HDL. This ratio is an indicator of cardiovascular disease risk and although this ratio can return to normal levels after stopping steroids, atherogenesis (fat deposition in the vessel walls) may have already occurred.”
5. Six out of every ten people in the UK have raised cholesterol levels
According to HEART UK over half of all adults in England have raised cholesterol, a major risk factor for the development of heart disease and strokes [viii]. There are no obvious telltale signs of high cholesterol in the body. Because of this, it is very important to regularly monitor your levels to make sure you are not at risk. Medichecks' Cholesterol Check is the perfect way to measure triglycerides, LDL and HDL cholesterol levels as well as determining your risk of heart disease based on the ratio of HDL to total cholesterol.
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[i] Nhlbi.nih.gov. (2018). Questions and Answers on Cholesterol and Health with NHLBI Nutritionist Janet de Jesus, M.S., R.D. | National Heart, Lung, and Blood Institute (NHLBI). [online] Available at: https://www.nhlbi.nih.gov/news/2015/questions-and-answers-cholesterol-and-health-nhlbi-nutritionist-janet-de-jesus-ms-rd [Accessed 10 Oct. 2018].
[ii] Foundation, T. (2018). Saturated and trans fat. [online] The Heart Foundation. Available at: https://www.heartfoundation.org.au/healthy-eating/food-and-nutrition/fats-and-cholesterol/saturated-and-trans-fat[Accessed 10 Oct. 2018].
[iv] H, M. (2018). Cholesterol and diabetes | Expert advice from HEART UK. [online] Heartuk.org.uk. Available at: https://heartuk.org.uk/health-and-high-cholesterol/cholesterol-and-diabetes [Accessed 10 Oct. 2018].
[v] Gylling, H., Hallikainen, M., Pihlajamäki, J., Simonen, P., Kuusisto, J., Laakso, M. and Miettinen, T. (2010). Insulin sensitivity regulates cholesterol metabolism to a greater extent than obesity: lessons from the METSIM Study. Journal of Lipid Research, 51(8), pp.2422-2427.
[vii] Publishing, H. (2018). Cholesterol, the mind, and the brain - Harvard Health. [online] Harvard Health. Available at: https://www.health.harvard.edu/newsletter_article/cholesterol-the-mind-and-the-brain [Accessed 10 Oct. 2018].