What is Cholesterol?

What is Cholesterol?

When someone mentions the word “cholesterol”, we almost always think fat, because in essence, cholesterol technically is fat. It is a lipid (fat) produced by the liver and is vital for normal body function. It is a chemical substance (organic) in the same classification as a waxy steroid of fat, an important structural part of mammalian cell membranes and is required to establish proper membrane permeability and fluidity.

“Cholesterol” the word, is a combination of the Greek word “chole”, which means “bile” and “stereos”, meaning “stiff” or “solid”.

Each and every cell in our body has cholesterol in its outer layer. It is a building block for cell membranes and for hormones like estrogen and testosterone. More or less 80% of the body’s cholesterol is produced by the liver, and the rest is from the food we eat. The primary sources of dietary cholesterol are poutlry, meat, seafood, and dairy/milk products.

Organ meats, such as liver and intestines are especially high in cholesterol, while foods of plant origin does not contain cholesterol. Right after a meal, dietary cholesterol is absorbed from the intestine and stored in the liver.

cholesterol-rich sandwich that has meat, egg and cheese

This photo is an example of food high in cholesterol. It includes meat, cheese and an egg.

The liver is able to regulate the blood stream’s cholesterol levels and can secrete cholesterol if it is needed by the body. The functions of cholesterol include the following: Builds and maintains the cell membranes’ outer layer, preventing hydrocarbon crystallization in the membrane, Cell membrane permeability – cholesterol is essential in determining which molecules can pass into the cell and which cannot. It modulates membrane fluidity over the physiological temperature range. Inside the body’s cell membrane, cholesterol also is essential for intracellular transport, nerve conduction and cell signaling. Cholesterol is also important for the structure, function of invaginated caveolaeand clathrin-coated pits, which includes clathrin-dependent and caveola-dependent endocytosis.

Cholesterol insulates nerve fibers, involved in sex hormone production – estorgens and androgens alike. Used for hormone production released by the adrenal glands (cortisol, aldosterone, corticosterone, and others), cholesterol aids in bile production. It also converts sunshine into vitamin D and important in metabolizing fat-soluble vitamins, that include vitamins A, D, E, & K. Cholesterol travels in the blood by molecules called lipoproteins. Lipoproteins are any complex or compound, containing both lipid (fat) and protein. The three main types are LDL (low density lipoprotein), HDL (high density lipoprotein) and Triglycerides. LDL or low density lipoprotein – is often referred to as “bad cholesterol”. LDL is the culprit responsible for carrying cholesterol from the liver to the cells.

If too much is carried, too much for the cells to use, a harmful buildup of LDL begins. This lipoprotein may elevate the risk of arterial disease if levels are too high. Human blood contains approximately 70% LDL – varying from person to person. HDL or high density lipoprotein – is often referred to it as good cholesterol and is said to prevents arterial disease, and does the opposite of LDL; it takes the cholesterol away from the cells and back to the liver.

In the liver it is either broken down or expelled from the body as waste. Triglycerides are the chemical forms in which most of the fat appear in the body, as well as in food, and they are present in blood plasma. Triglycerides, together with cholesterol, combine to form the plasma lipids (blood fat). Triglycerides contained in plasma originate either from fats the food we eat, or are made by the body from other energy sources, including carbohydrates. The Calories which we consume but are not used immediately by our tissues are converted into triglycerides and are stored in fat cells.

When our body needs energy and there is no food as an energy source, triglycerides are released from fat cells and used as energy; hormones control this process. Cholesterol is very important and needed for human health; however, elevated levels of cholesterol in the blood have been associated to artery damage and cardiovascular disease. We should select food that contain healthy fats, try to limit food which has a high amount of saturated fat, and abstain from food with trans fat. We need to end the low-fat myth. What actually is important is the type of fat we eat. “Good” fats (HDL), the monounsaturated and polyunsaturated fats minimizes disease risks.

“Bad” fats (LDL), the saturated and, especially, trans fats (a specific type of fat formed when liquid fats are made into solid fats by the addition of hydrogen atoms)—increase disease risk. Foods that are rich in good fats include nuts, seeds, fish. and vegetable oils (like olive, canola, sunflower, soy, and corn). Foods with a high level of bad fats include red meat, butter, cream, cheese, and ice cream, as well as processed foods made using trans fat from partially hydrogenated oil. Know the better choices; vegetable oils instead of butter, salmon instead of steak—and those food which do not contain any trans fat. The key to a healthy diet is to choose food that have more good fats than bad fats; good cholesterol over bad cholesterol.