Propylene glycol alginate (PGA) is an additive used mainly as a thickening agent in certain types of food. It is made from the kelp plant or from certain kinds of algae, which is processed and transformed into a yellowish, grainy chemical powder. The powder is then added to foods that require thickening. It has been used for many years as a food preservative, and many food manufacturing companies use it in common items.
There are three primary reasons for using propylene glycol alginate. First, it thickens liquid but it also stabilizes it. For example, the foam in beer can be stabilized by using this chemical as can fruit juices or foamy dairy products. It is also considered an emulsifier, which means that it keeps foods fresher because it acts as a preservative. Certain foods have a tendency to change color or consistency over a period of time, for example, and this chemical helps to slow down that process.
Most types of gel-like foods, including yogurt, jellies and jams, ice cream, and salad dressing, contain this additive. Certain condiments and chewing gum also contain it, as do some kinds of cosmetics.
Although it is considered a safe additive, there have been reports of negative side effects. It can produce stomach upset and nausea, whether it's ingested or used on the skin as a cosmetic. When it is only used cosmetically, it can cause allergic reactions that include hair loss, rashes, and eye irritations. Cosmetic use is the most common cause of side effects. Other skin-related allergies can occur when household cleaners that contains this ingredient are used.
It is unclear if this chemical additive should be used by expectant mothers because it is thought to be a teratogen, which means that it might cause birth defects. Because it is easily absorbed into the skin, it is thought that exposure can cause damage to the kidneys as well as the liver. High doses can cause seizures in children. Despite these potential problems, propylene glycol alginate is one of the most commonly used chemical additives.