Palmitic acid is the fatty acid most abundant along with stearic acid. It plays a supporting role in plant, animal and human organisms. Most of the palmitic acid is bound in triglycerides.
What is palmitic acid?
Palmitic acid is a very common saturated fatty acid. Saturated means that it does not contain a double bond in the molecule. In all fats and fatty oils, a high percentage of palmitic acid is bound to glycerol. Since glycerol contains three hydroxyl groups, it usually forms triple esters with different fatty acids, which are called triglycerides. Palmitic acid consists of 16 carbon atoms linked together in chains. Of these, 15 carbon atoms only form bonds to hydrogen and other carbon atoms. The 16th carbon atom is part of a carboxyl group, where a C=O double bond and a bond to a hydroxyl group are formed. The esterification with the hydroxyl group of alcohols takes place at the carboxyl group. In this sense, glycerol is a triple alcohol and forms a triglyceride with three fatty acids, which appears as a typical fat or fatty oil depending on the fatty acid composition. Palmitic acid and stearic acid are the main components of this substance class. It is indeed one fatty acid among many. However, it plays a special role. In the metabolism of many organisms it occurs as the main intermediate product. Like all fatty acids, palmitic acid is built up step by step by the addition of two carbon atoms in an ever-repeating process. In nature, palmitic acid usually occurs in bound form. In free form, however, it forms colorless, crystalline sheets which melt at 61-64 degrees and evaporate at 351 degrees. It is virtually insoluble in water, but has good solubility in many organic solvents. The term palmitic acid is derived from palm oil, because this fatty acid is particularly abundant there.
Function, effect and tasks
Palmitic acid is significantly involved in the structure of all organisms. Thus, in both plant and animal organisms, it is found mainly in triglycerides. There, along with other fatty acids and glycerol, it serves as the main energy store. Furthermore, all cell membranes consist of phospholipids. Phospholipids are formed by esterification of fatty acids with phosphoric acid. They also contain palmitic acid as a major component. Phospholipids have both a lipophilic and a hydrophilic moiety. The phosphoric acid functions as the hydrophilic part, while the fatty acids, including palmitic acid, represent the lipophilic part. This peculiarity allows phospholipids to demarcate different phases from one another and at the same time mediates the phase transition of different substances. Above all, they cause the demarcation of cells from the intercellular space, so that important biochemical processes can take place undisturbed within the cells. As already mentioned, however, palmitic acid is also the main component of triglycerides, which serve the organism as energy stores. In times of food surplus, fat reserves are built up, whereby mainly a new synthesis of fatty acids occurs. Palmitic acid is the first fatty acid formed during lipogenesis. It serves as a starting material for the synthesis of higher fatty acids. In the case of food deficiency, these fat reserves and thus also the fatty acids are gradually broken down again. Palmitic acid thus serves as the starting material for the formation of higher fatty acids and thus for the formation of triglycerides as energy stores and phospholipids as the main component of cell membranes.
Formation, occurrence, properties, and optimal values
Palmitic acid occurs ubiquitously. Every organism is dependent on palmitic acid. Both plant and animal or human organisms are capable of producing palmitic acid. In this process, units of two carbon atoms each are attached to the carbon chain in the course of lipogenesis. As a result, the fatty acids generally consist of even-numbered chains. In the case of palmitic acid, there are 16 carbon atoms. Stillingia oil (60-70 percent) contains particularly high levels of palmitic acid. Stillingia oil is obtained from the flowering plant Stillingia sylvatica, which is native to the southeastern United States. Palm oil, in turn, contains between 41 and 46 percent palmitic acid. It is followed by beef tallow, lard, butterfat and cocoa butter with up to 30 percent.Cottonseed oil and avocado oil are also rich in palmitic acid. The depot fat of humans contains between 20 and 30 percent of this fatty acid. Palmitic acid is also used in cosmetic products and soaps. It gained sad notoriety as an important starting material for the production of napalm.
Diseases and disorders
Palmitic acid is a saturated fatty acid and, according to conventional views, should lead to high blood lipid levels with the resulting consequences if consumed in excess. However, contradictory results have been obtained in various studies. It has even been shown that saturated fatty acids such as palmitic acid increase blood lipid levels, but in addition to the bad LDL cholesterol, the good HDL cholesterol is also increased. Since their ratio to each other does not change in the process, higher consumption of palmitic acid has no effect on health according to certain studies. However, the ratio of saturated to unsaturated fatty acids also plays a role. However, this ratio is shifted in favor of the saturated fatty acids and their starting material palmitic acid, especially in the case of an increased diet with carbohydrates, since saturated fatty acids are always formed first. These can only subsequently be converted into unsaturated fatty acids. However, this biochemical reaction mechanism is limited in the human organism, so that an excessive diet of carbohydrates increasingly produces palmitic acid, which leads to a disturbance in the ratio of saturated to unsaturated fatty acids. As a result, insulin resistance, toxic effects on the pancreas, slowing of fat burning and pro-inflammatory processes are formed.
