What is cholesterol?
Cholesterol is a type of fat-like chemical that is an essential component of every cell in your body. Cholesterol is a part of cell walls, and is used to produce hormones and bile. While cholesterol is found in the food you eat, your body produces all the cholesterol that it could need in the liver. It is estimated that 80% of your circulating cholesterol levels are determined by your genetics, and the remaining 20% can be influenced by your lifestyle choices.
How is cholesterol transported?
Cholesterol is carried through the blood inside lipoprotein particles; these are capsules made of a fat and protein outer layer that allow other fats contained inside to travel through blood. The lipoprotein particles are produced in the liver and are packed with cholesterol and triglycerides (fats stored as energy reserves), and released into the bloodstream to transport the fats to cells throughout the body. The newly created lipoproteins in the liver are large very-low density lipoprotein (VLDL) particles.
The lipoproteins are categorised by their protein-to-fat content; the largest lipoproteins contain the most fats and therefore have the lowest density of protein. As the lipoproteins exchange fats to cells they decrease in size, and increase in protein density. The progressively smaller particles are categorised as small VLDL, intermediate-density lipoproteins (IDL) and low-density lipoprotein (LDL).
How does cholesterol contribute to health?
This brings us back to familiar territory; LDL-cholesterol is popularly referred to as “bad” cholesterol, and for good reason. These smaller lipoprotein particles are notorious for embedding into the innermost-layer of the arterial walls. If the levels of circulating LDL-cholesterol remain high, the LDL particles will contribute to building plaques in the arteries, a process known as atherosclerosis and a cause of coronary heart disease (CHD). However, small VLDL and IDL particles can also enter the arterial walls and contribute to atherosclerosis, but are typically present in smaller concentrations than LDL particles.
Fortunately, the liver produces lipoproteins that work in the opposite way to LDL particles, removing fats and cholesterol from cells, including from the fatty deposits in arterial walls. These are high-density lipoprotein (HDL) particles, or the “good” cholesterol. HDL particles start as flattened lipoprotein shells in the liver that expand as they collect lipids from cells. This is how HDL-cholesterol is unique from non-HDL cholesterol (VLDL, IDL and LDL), and is associated to reduced CHD risk.
How are cholesterol levels measured?
Taking a closer look at cholesterol is important because it is a major risk factor for CHD, and more importantly, measures to reduce cholesterol levels reduce the risk of CHD. A routine blood test called the lipid profile (or lipid panel) can evaluate this risk. The lipid profile test measures total cholesterol, LDL-cholesterol, HDL-cholesterol and triglycerides. The most common method for determining these values is through a direct measurement of total cholesterol, HDL-cholesterol and triglycerides, and then calculating the estimated value for LDL-cholesterol using a formula called the Friedewald formula.
What this actually means is that the ‘LDL-cholesterol’ result returned in most laboratory reports is not specific for just LDL-cholesterol, but a combination of some non-HDL lipoproteins. For most people, their ‘LDL-cholesterol’ result is the combined total of a small proportion of small VLDL- and IDL-cholesterol, and the majority remainder of LDL-cholesterol. Despite the lack of specificity, each of these lipoprotein subtypes do contribute to atherosclerosis, and partly explains why indirect LDL-cholesterol measurements continue to be the most common practice for first-line screening.
In fact, several more sophisticated methods for directly measuring LDL-cholesterol and other lipoprotein subtypes exist, but these advanced methods don’t provide a proven clinical advantage for screening in a healthy population. Instead other methods can be valuable when ordered by your doctor to monitor drug therapy or metabolic disease.
Why might LDL-cholesterol measurements fail?
LDL-cholesterol results can fail because the triglycerides are too high. As mentioned above, LDL-cholesterol levels are calculated from the direct measurements of total cholesterol, HDL-cholesterol and triglycerides. However, using this formula to calculate LDL-cholesterol requires triglycerides to less than 4.2 mmol/L (or 372 mg/dL).
Lykon biomarker tests should be taken in the morning before eating, and after a 12-hour fast. If you have eaten before taking a test it is possible that the triglyceride levels have increased somewhat. If you have fasted before taking the test, then it is recommended to take action to reduce their triglyceride levels; this should include meeting with your doctor, especially if you also have high total cholesterol or high HbA1c.
What are the cholesterol levels of Lykon users?
It is recommended to keep total cholesterol levels below 5 nmol/l (or 200 mg/dl), especially as you get older. Keeping cholesterol below this level is important to minimise the development of atherosclerosis. Other major risk factors that contribute to atherosclerosis include high blood pressure, diabetes and smoking. Approximately 57% of Lykon users have total cholesterol levels above the recommended threshold, and LDL-cholesterol levels are similarly too high in 44% of users (as of January 2019). Similar to the general population, older Lykon users are more likely to have a higher cholesterol level.
The best practice is to keep both total cholesterol and LDL-cholesterol low. Cholesterol rises with age, so you need to be proactive in keeping cholesterol levels low. Reducing cholesterol by 10% can decrease your risk of heart disease in the next 5 years by as much as 50%.
How can cholesterol levels be improved?
There are a number of healthy lifestyle changes that can help reduce both cholesterol levels and the risk of heart disease. This includes managing bodyweight, getting 150 minutes of aerobic exercise each week, and minimising dietary saturated and trans fat intake in exchange for more nutrient-dense low-calorie foods (such as fruits, vegetables, and high fibre foods). It is important to incorporate these healthy lifestyle strategies
You can measure your cholesterol levels with a number of the Lykon tests, including myWeight Control, myFitness and myEssentials. These tests will measure your complete lipid profile, and will provide you with personalised lifestyle and nutrition recommendations suited to your needs.
Abbreviations
CHD – coronary heart disease
HDL – high density lipoprotein
IDL – intermediate density lipoprotein
LDL – low density lipoprotein
VLDL – very low density lipoprotein
References
Allaire J, Vors C, Couture P, Lamarche B. LDL particle number and size and cardiovascular risk: anything new under the sun? Curr Opin Lipidol. 2017;28: 261–266.
Clarke R, Frost C, Collins R, Appleby P, Peto R. Dietary lipids and blood cholesterol: quantitative meta-analysis of metabolic ward studies. BMJ : British Medical Journal. BMJ Publishing Group; 1997;314: 112.
Holmes MV, Ala-Korpela M. What is “LDL cholesterol”? Nat Rev Cardiol. 2019; doi:10.1038/s41569-019-0157-6
Sniderman AD, Lawler PR, Williams K, Thanassoulis G, de Graaf J, Furberg CD. The causal exposure model of vascular disease. Clin Sci . 2012;122: 369–373.
Tabas I, Williams KJ, Borén J. Subendothelial lipoprotein retention as the initiating process in atherosclerosis: update and therapeutic implications. Circulation. 2007;116: 1832–1844.
WHO | Raised cholesterol. World Health Organization; 2015; Available: https://www.who.int/gho/ncd/risk_factors/cholesterol_text/en/
