Cholesterol often has a bad reputation due to its association with cardiovascular disease. However, it plays a crucial role in our body, essential for life. Without cholesterol, vital functions such as hormone production, cell membrane structure, and fat digestion would be impossible.
Approximately 20% of the cholesterol in our body comes from our diet. The remaining 80% is produced by our body, primarily by the liver. This endogenous cholesterol synthesis is essential for maintaining vital bodily functions such as hormone production, cell membrane integrity, and bile acid formation.
Cholesterol is a crucial component of cell membranes, helping to maintain their structure and fluidity. Without it, cell membranes would lack proper form and stability, making the formation and function of cells and organs impossible. Thus, without cholesterol, life cannot exist.
Cholesterol is necessary for producing bile salts, which aid in the digestion of dietary fats. It is also essential for synthesising vitamin D, testosterone, estrogen, and many other vital hormones and substances. However, like many things in life, balance is key. While cholesterol is not inherently bad, having too much can be harmful.
A fasting lipid profile provides insights into our cholesterol status. When you have your fasting lipid profile taken, there are four basic readings provided:
1. Total Cholesterol: This value represents the total amount of cholesterol circulating in your blood.
2. Low-Density Lipoprotein (LDL): Often labeled as "bad" cholesterol, LDL transports cholesterol from the liver to the blood vessels. Since cholesterol is not water-soluble, it requires a transporter like LDL to travel through the bloodstream. LDL is associated with oxidative reactions in the arterial endothelium, leading to plaque formation and narrowing of blood vessels, increasing the risk of cardiovascular disease.
3. High-Density Lipoprotein (HDL): Another transporter like the LDL but of a different route. HDL transports cholesterol from the blood vessels back to the liver for processing and removal from the body.
4. Triglycerides: The storage form of fat in the body. When needed, triglycerides are converted into very-low-density lipoprotein (VLDL), which, after delivering triglycerides to cells, becomes small dense LDL. Hence the association to risk of cardiovascular disease as well.
Let's delve deeper into LDL. Recent research has distinguished two forms: large buoyant LDL and small dense LDL. Only the small dense LDL is implicated in damaging the endothelial walls, potentially leading to cardiovascular events. In contrast, large buoyant LDL does not contribute to endothelial damage and is not associated with increased cardiovascular risk. Therefore not all LDLs are bad.
In a fasting lipid serum test, the reported LDL result typically encompasses both forms: small dense LDL and large buoyant LDL. How do we distinguish if the composition of the raised LDL is mainly small dense LDL or large buoyant LDL?
The answer to that is our triglycerides level. Triglycerides serve as the storage form of cholesterol in our body. When additional energy is needed, triglycerides are converted into VLDL and transported to tissues. After delivering triglycerides, VLDL breaks down into small dense LDL. Therefore, triglyceride levels can serve as a proxy for small dense LDL values.
If your lipid profile shows high LDL and low triglycerides, it suggests that LDL values are predominantly represented by large buoyant LDL. Conversely, high levels of both LDL and triglycerides indicate a higher proportion of small dense LDL in your serum.
Stay tuned as we explore more about Triglyceride to HDL ratios and what they reflect in the upcoming article.
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