Fats and oils (4)

LDL, HDL-cholesterol and triglycerides
Cholesterol, being only slightly soluble in water, dissolves to a very small concentration in blood, which is predominantly water-based. To increase the concentration of cholesterol in the blood and the tissues where they are to be carried to, they are transported in lipoproteins.

Lipoproteins are lipid (fat) and protein complexes that move around the blood carrying cholesterol. There are different kinds of lipoproteins in the blood stream, but two are of interest to us in this article. Depending on the density, we have the Low Density Lipoprotein, otherwise known as LDL-Cholesterol and secondly is the High Density Lipoprotein, HDL-cholesterol. LDL particles are the main transporters of cholesterol in the blood stream. They transport cholesterol from the liver to the cells where they are used, while HDL transports cholesterol from the cells to the liver to be excreted or to other tissues where they are used for hormone synthesis.

Furthermore, LDL-cholesterol contributes to plaque formation on the wall of the arteries. This causes a thickening of the wall of the artery and makes it less flexible. This condition is known as arteriosclerosis. This also reduces the lumen of the artery and may give way to clot formation if there is a crack in the wall of the artery. Such a clot may block the artery and lead to either heart attack or stroke depending on the artery that is affected. HDL-cholesterol, on the other hand, like a scavenger, picks up the LDL-cholesterol from the arteries and returns them to the liver where they are broken down and excreted from the body. An optimal level of HDL-cholesterol will reduce the risk of and prevent heart disease. Cholesterol destined for excretion or utilization for hormone synthesis both of which are controlled by HDL-cholesterol leads to reduction of cholesterol in the blood circulation. A high concentration of HDL particles supports good health in the presence of low of LDL-cholesterol. On the contrary, low HDL-cholesterol and high LDL-cholesterol is associated with arteriosclerosis, heart disease or stroke.

A third kind of fat known as triglycerides also play a significant role in the formation and atheromatous disease and heart disease.

One triglyceride compound is a combination of one glycerol molecule and three fatty acids. Chemically, it is said to be an ester due to the bond between the glycerol and fatty acids. They are the main fat that make up the body fats in human beings. Also, they are vital energy sources in the body and play an important role as transporters of dietary fat. Triglycerides are stored in fat cells and released by hormonal action when there is a need for energy in between meals in the body.
Health implications of triglycerides

High blood level of triglyceride is associated with the hardening and thickening of the arteries that is characteristic of arteriosclerosis. Excessive triglyceride in the blood, therefore, increases the risk of heart attack, heart disease and stroke. This is made worse when there is concurrent increase in the level of LDL (bad)-cholesterol and decrease in HDL (good)-cholesterol.

Triglycerides differ from cholesterol in that it is a store for calories that are not yet needed. Whenever there is need for energy, the triglyceride stores will be broken down. When a gram of triglyceride is broken down, it releases 9Kcal of energy as against 4kcal when one gram of glucose is broken down. On the other hand, cholesterol is used for cell build up and for cell membrane stability. It is also used in the synthesis of certain hormones. For example, synthesis of the steroid hormones and the sex hormones (progesterone, oestrogen and testosterone) and the adrenal hormones, cortisol and aldosterone.

Furthermore, it has been discovered that very high levels of triglyceride may be associated with pancreatitis.
There are some conditions that increase the risk of heart disease, which also have high triglyceride level as signs. These conditions include obesity, high blood pressure, high blood sugar level, metabolic syndrome and abnormal cholesterol level. High triglyceride level can also be found hypothyroidism, wrongly managed diabetes (type 2) and liver disease.