Fatty acids are the building blocks of fat molecules. They contain carbon atoms bonded to other carbon atoms. If all of the carbon atoms are bonded together with single bonds, then the carbons are said to be saturated. A fatty acids containing only single bonded carbon atoms is a saturated fatty acid. When two carbons are bonded together by a double bond, the carbons are unsaturated. If the fatty acid has one double bond it is a monounsaturated fatty acid. If it contains two or more double bonds it is called a polyunsaturated fatty acid.
Cholesterol is a fatty substance produced by every cell in the body that is vital for health. The majority of cholesterol is excreted from the liver in bile and reabsorbed from the intestines. Cholesterol is the precursor for the synthesis of the various steroid hormones, including estrogen, testosterone, cortisol, cortisone and vitamin D. It is the leading organic molecule in the brain and is needed for brain function. Blood cholesterol carries antioxidant vitamins tot he tissue.
Since the body produces all the cholesterol it needs, you don't need cholesterol in your diet at all. Foods from plant sources don't contain any cholesterol. Cholesterol is found in foods from animal sources. Too much cholesterol can lead to narrowing and blockage of the arteries, decreasing the blood flow and causing heart problems. High cholesterol can also cause the formation of gallstones. Blood cholesterol levels should be less than 150 mg/dl.
There are different forms of cholesterol, "good" and "bad". The distinction has to do with how it is carried around the blood. Chemicals called lipoproteins, which are combined fatty proteins, are used for transporting cholesterol in the bloodstream. HDL (High Density Lipoprotein) cholesterol is known as "good", because any excess can be sent to the liver and dealt with. LDL (Low Density Lipoprotein) cholesterol is known as "bad", because it cannot be sent to the liver and remains to potentially clog arteries.
Saturated fat is a fat that is solid at room temperature. It is found in greatest amounts in food from animals, like dairy products and meat, and in some vegetable products like coconut oil, cocoa butter, palm kernel oil and palm oil. Saturated fat is used to compose the layer of fat under the skin. This helps us insulate the body. However, saturated fat is also a component of atherosclerotic plaques that form inside blood vessels and can eventually block the flow of blood. Saturated fat is the most important dietary factor in raising cholesterol levels and blocking arteries. It raises LDL ("bad" cholesterol) levels and depresses HDL ("good" cholesterol) levels. Common saturated fatty acids are butyric acid, palmitic acid and stearic acid.
Monounsaturated fat is an unsaturated fat that is usually liquid at room temperature. It is found primarily in plant foods like avocados, olives and nuts and in various vegetable oils like olive oil and canola oil. A common monounsaturated fatty acid is oleic acid. Monounsaturated fat does not raise LDL ("bad" cholesterol) levels as much as saturated fat and does not depress HDL ("good" cholesterol) levels as much as polyunsaturated fat. It is therefore the most recommended type of fat for a healthy diet. It does contain the same amount of calories and should be used in moderation.
Polyunsaturated fat is, like monounsaturated fat, an unsaturated fat that is usually liquid at room temperature. As cells are being formed in our body, polyunsaturated fatty acids are used to form the cell wall membranes. If there aren't enough polyunsaturated fatty acids in our body, saturated fatty acids will be used. This can happen when the diet is high in saturated fats and low in polyunsaturated fats. The membrane that is formed with the help of saturated fatty acids will not have the same properties as a membrane made up of polyunsaturated fatty acids. In the long term this can lead to health problems. Polyunsaturated fat is mostly found in plant foods like most nuts and in vegetable oils like corn, soybean and safflower. When used in small amounts, polyunsaturated fat tends to lower only LDL ("bad" cholesterol). When consumed in larger amounts, it lowers both HDL ("good" cholesterol) and LDL levels.
Monounsaturated or polyunsaturated fat whose molecules contain trans double bonds between carbon atoms. Trans fats can be either man-made, caused by hydrogenation (see hydrogenated fat) or are found naturally in dairy and meat products. Trans fatty acids act like saturated fat. They are considered as bad or even worse than saturated fat, because they are not easily recognized by our body. This type of fat takes longer to digest and stays in our body a long time, which can cause weight gain and digestive problems. They raise LDL ("bad" cholesterol) levels in the blood increasing the risk of heart disease and stroke.
Hydrogenation turns liquid vegetable oil into solid or semi-solid fat. Unsaturated fats will go rancid and decompose in the presence of oxygen. This process can be stopped by hydrogenation. Hydrogen is mixed with the fat at a high temperature in the presence of a catalyst like nickel and in the absence of oxygen. This process will raise the fat's melting point, turning liquid vegetable oils into more solid fats like margarine or shortening. Fully hydrogenated fats are solid, while partially hydrogenated fats are hardened, but not fully solid. Trans fats are the result of the hydrogenation.
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