What is Fat? Where does It Come from?Simple fats are compounds of triatomic alcohol glycerol with three fatty acids and include only three chemical elements. They are carbon, hydrogen and oxygen. It should be remembered that a man can synthesize fat from carbohydrates. This is especially noticeable in beer drinkers, their distinguishing feature is "beer belly" (though beer contains no fat). Different animal fats vary in chains length of fatty acids and the presence of double bonds. The less double bonds, the thicker molecule of fatty acids adjoin each other and the fat is more solid. Vegetable fats remain liquid even in the refrigerator. Organism is able to build on and shorten the chains, and that is why it can be satisfied with any fat. Still, the consumption of animal fats, including butter, is necessary for human. These fats contain vitamin A and D (carrots and yeast have their predecessors - carotene and ergosterine). Polyunsaturated fatty acids are in the vegetable fats. They are linoleic and linolenic acids which are very important for human body. They are so important that are regarded as vitamins (vitamin F). In addition, vegetable oils are a source of vitamin E, which is found only in the liver of the animal products. It is interesting that a heart can use fatty acids for its work, but brain needs pure glucose. Muscles use glucose at low load, and fat - at high load. So, it "eats" glucose during the house work and in the kitchen without use of fat reserve. The fat content varies in the food. There is little fat in vegetables, fruits and cereals, but many ones in butter and vegetable oil. There are also compound fats which include trace elements, more often phosphorus. Such fats have the other structure, for example cholesterol. It is needed for building of cell membranes, synthesis of hormones etc. Simple and compound fats are also known as lipids. Most fats in intestine go through the splitting (lipolysis) by the lipase enzyme, which is excreted in the juice of the pancreas. Bile emulsifies fat particles, transforming them into tiny droplets that are available for lipase. As a result, fat is decomposed into its component of fatty acids and glycerol, which are absorbed into the walls of the small intestine. Specific human fat is synthesized from a large set of fatty acids in the mucous tunic of intestine. The molecules of fat, joining together and combining with protein, form larger droplets of chylomicrons, which with the flowing of lymph go in the pectoral lymphatic channel. Then it penetrates into the blood flow through the capillaries into all organs. Capillary walls excrete a special enzyme - lipoprotein lipase. It detaches fatty acids from its carrier glycerol, and then free fatty acids are captured by tissues. The most active are the capillaries of fat depot, lungs and heart. In the human body more than 80% of fat is formed by fatty acids and only 20% derived from carbohydrates. But the camel, for example, synthesizes almost 100% of its fat from the grass and water. Read also: |