What is Cholesterol?
Cholesterol is a waxy, fatlike substance primarily synthesized in the liver but can also be obtained via animal and dairy products in the diet. Considered a steroid, an alcohol and a lipid, cholesterol has many functions in the body that are essential.
Most people think cholesterol is just “bad fat” that should be avoided. On the contrary, it is more than just fat, it is a multifaceted substance involved in various essential mechanisms in the body, taking advantage of its unique chemical structure as fat, protein and steroid.
Some of roles that cholesterol plays in the body include:
Cell membrane component. Cholesterol is a key component in cell membranes that provides stability and fluidity in the fluid mosaic model of membranes. Cell membranes surround individual cells and provide the stability that cells need in order to separate and compartmentalize various components and structures within and around the cell. In fact, the structural stability and intact nature of cell membranes is used as diagnostic tools. Without intact cell membranes, important enzymes and components would essentially spill out of the cell. These enzymes that have spilled out are what physicians look for. For example, when examining the health of your liver, your physician is looking to see if liver enzymes are elevated in your blood. If they are, your physician may suspect that something has damaged liver cell membranes and caused these normally undetectable enzymes to be spilled into the bloodstream.
Cholesterol helps to improve the stability and fluidity of cell membranes because the hydrocarbon component of cholesterol (water-hating) is embedded amongst the phospholipid tails of the membrane bi-layer (hydrophobic) while the hydroxyl group interacts with the hydrophilic phosphate portion (water-loving) of the cell membrane. Simply put, the chemical structure of cholesterol allows it to interact with parts of the membrane that is both water-loving and water-hating in nature.
Cholesterol as a precursor. Cholesterol is a major precursor in the synthesis of vitamin D, steroid hormones and sex hormones. Examples of the various steroid hormones include corticosteroids such as aldosterone (a mineralcorticoid), cortisol (a glucocorticoid) and cortisone. These hormones are involved in a wide range of systems including immune response, stress response, blood electrolyte maintenance, carbohydrate and fat metabolism, protein catabolism and behavior. Examples of the various sex hormones include testosterone, estrogen and progesterone.
Cholesterol and Bile. Bile is a key component in digestion as it helps to break down large fat globules into smaller droplets so that it can be absorbed properly. This process is known as fat emulsification. Cholesterol plays a role in the formation of bile acids such as cholic acid, chenodeoxycholic acid, taurocholic acid and glycocholic acid.
Though cholesterol is clearly a necessary component in the body, not much is actually needed for normal and healthy functioning. The problem of cholesterol lies in the fact that too much cholesterol in your bloodstream can cause health problems. It is the excess levels of cholesterol and the proper shuttling of this excess within the body that contributes to disease.