They can be of both plant and animal origin. Depending on the chemical nature at room temperature, they may be liquid, thick and stiff. Chemically, they are esters of fatty acids with glycerol of various nature, trihydric alcohol. To one molecule of glycerol is joined three acid molecules, identical or different. Under the influence of sodium or potassium hydroxide ester bonds are interrapted, fatty acids form salt with an alkali, which are common soap, solid sodium, liquid - with potassium and glycerol is remained in solution.
Fats and oils are important food products, used in engineering, cosmetics and also have a pharmaceutical use. So-called unsaturated fatty acids, having in the molecule one or two (as linoleic), three (as linoleic) or four (as arachidonic acid) double bonds between carbon atoms and occur only in vegetable fats and the so-called fish oil, in human body cannot be synthesized, but the need for many biochemical processes, and therefore is indispensable to carry foodstuffs. A mixture of unsaturated fatty acids is called vitamin F. Directly from the drug is applied castor oil - as a laxative. Ointments, emulsions, pastes, fatty herbal extracts or essential oils are prepared by fats which promote the absorption of active substance by the body and continue to mitigate their effects. Fats and fatty acids are unstable, especially unsaturated, they oxidize, harden, become darker, gaining a bad smell. The attention should be paid when using them. The most common in our environment - sunflower and canola oil, flaxseed, and corn, in Central Asia - cotton, and in the international practice - olive (olive oil), peanut, coconut and palm.