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EFA deficiency in humans is often associated with skin aging and can lead to a dry, scaly appearance and a loss of elasticity and barrier integrity. [...] PC is an important tool for the external supply of EFA to aging skin or for persons suffering from malnutrition, acne, and other diseases affecting the skin lipid metabolism.
inform December 2009, Vol. 20 (12) 793 Phospholipids A phospholipids primer Moghis U. Ahmad In the last few years, phospholipids made from marine sources have started to enter the nutritional supplement market. The first product of this kind was made from krill, a small crustacean fished Phospholipids are prime building blocks of all life. from cold Antarctic waters (for more on krill, see inform 18:588– The history of phospholipids begins with the isola- 592, 2007). New phospholipid products entering the nutritional tion from chicken eggs of lecithin, a crude mixture supplement market are now made from the roe of Pacific and Atlan- tic Ocean cold-water fish species. of various phospholipids and other lipids, by the Structurally, phospholipid molecules consist of a hydrophilic French researcher Maurice Gobley around 1847. polar head group and a hydrophobic nonpolar tail (see Fig. 1). The word is derived from “lekithos,” Greek for egg The polar head group contains one or more phosphate groups. The hydrophobic tail is made up of two fatty acyl chains. When yolk. many phospholipid molecules are placed in water, their hydro- In the 1920s, technological advances in Germany made the philic heads tend to “face” into the water and the hydrophobic large-scale production of lecithin from soybeans possible. Lecithin tails are forced to stick together at the surface, forming a bilayer. found applications as a nutritional supplement (i.e., a preparation Most biologically important phospholipids are phosphoglycer- intended to provide nutrients that are missing or not consumed in ides, which contain glycerol joining the head and tail. Examples sufficient quantities in a person’s diet). The same properties that of phosphoglycerides include PC, PS, phosphatidylethanolamine, make phospholipids so important for all life forms make them and phosphatidylinositol. important for food preparation, and today lecithin is widely used in The most abundant phospholipid in cell membranes is PC, the food industry as an emulsifier, a wetting agent for food instan- and therefore it is the most important building block for making tizing, a flow agent for chocolate manufacture, a baking stabi- replacement membrane mass. PC has exceptional emulsifying lizer and pan-release slip agent, a flour improver, and an animal properties, on which the liver draws to produce the digestive bile feed additive. Modern industrial processing of soy lec- ithin enriches its content of selected phospholipids that form the basis for commercially available nutraceutical phospholipid formulations. Currently, three phospho- lipids are commercially cost effective for nutritional supplements: phosphatidylserine (PS), phosphatidyl- choline (PC), and glycerophosphatidylcholine (GPC). All are safe to consume long-term, while offering valu- able proven benefits for health, such as enhancing brain health, protecting liver function, and serving as a source of choline. Egg yolks are the major source of phospholip- ids used by the pharmaceutical industry for parenteral nutrition, but for nutritional supplements egg phos- pholipids play no significant role because they have a relatively high cholesterol level and an unfavor- able saturated fatty acid profile. At one time, PS pro- duced from bovine brains was a widely used product in Europe. However, the incidence of bovine spongi- form encephalitis (BSE, or mad cow disease) made this product unusable and challenged researchers to find ways to isolate PS from an alternative source, such as soybean. FIG. 1. Chemical structure of selected phospholipids. DEC 09 INFORM.indd 793 12/2/09 3:16:08 PM 794 inform December 2009, Vol. 20 (12) fluid. The lining cells of the lung and intestines use PC to make the produce a wide variety of carrier systems that improve the solu- surfactant coatings essential to their gas and fluid exchange func- bility, stability, and delivery of active pharmaceutical ingredients tions, and PC is the predominant building block for the circulat- (API). The carrier system may be micelles, mixed micelles, and ing lipoproteins. liposomes. (Broadly defined, liposomes are lipid bilayers surround- ing an aqueous phase.) The emulsifyi
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