Psyllium
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Psyllium or Ispaghula is the common name used for several members of the plant genus Plantago whose seeds are used commercially for the production of mucilage.
The genus Plantago contains over 200 species. P. ovata and P. psyllium are produced commercially in several European countries, the former Soviet Union, Pakistan, and India. Plantago seed, known commercially as black, French or Spanish psyllium, is obtained from P. psyllium and P. arenaria. Seed produced from P. ovata is known in trading circles as white or blonde psyllium, Indian Plantago or Isabgol. Isabgol, the common name in India for P. ovata, comes from the Persian words isap and ghol, meaning “horse ear,” which is descriptive of the shape of the seed. India dominates the world market in the production and export of psyllium. Psyllium research and field trials in the U.S. have been conducted mainly in Arizona and also in Washington state.
Recent interest in psyllium has arisen primarily due to its use as an ingredient in high-fiber breakfast cereals, which is claimed to be effective in reducing blood cholesterol levels in those who consume it. Several studies point to a cholesterol reduction attributed to a diet that includes dietary fiber such as psyllium. Research reported in The American Journal of Clinical Nutrition concludes that the use of soluble-fiber cereals is an effective and well-tolerated part of a prudent diet for the treatment of mild to moderate hypercholesterolemia. Research also indicates that psyllium incorporated into food products is more effective at reducing blood glucose response than use of a soluble-fiber supplement that is separate from the food. Although the cholesterol-reducing and glycemic-response properties of psyllium-containing foods are fairly well documented, the effect of long-term inclusion of psyllium in the diet has not been determined. Cases of allergic reaction to psyllium-containing cereal have been documented.
Psyllium is produced mainly for its mucilage content, which is highest in P. ovata. The term mucilage describes a group of clear, colorless, gelling agents derived from plants. The mucilage obtained from psyllium comes from the seed coat. Mucilage is obtained by mechanical milling/grinding of the outer layer of the seed. Mucilage yield amounts to approximately 25% or more (by weight) of the total seed yield. Plantago-seed mucilage is often referred to as husk, or psyllium husk. The milled seed mucilage is a white fibrous material that is hydrophilic, meaning that its molecular structure causes it to attract and bind to water. Upon absorbing water, the clear, colorless, mucilaginous gel that forms increases in volume by tenfold or more. Psyllium is mainly used as a dietary fiber, which is not absorbed by the small intestine. The purely mechanical action of psyllium mucilage absorbs excess water while stimulating normal bowel elimination. Although its main use has been as a laxative, it is more appropriately termed a true dietary fiber.
The United States is the world’s largest importer of psyllium husk, with over 60% of total imports going to pharmaceutical firms for use in products such as “Metamucil”. In Australia, psyllium husk is used to make “Bonvit” psyllium products. In the UK, ispaghula husk is used in the popular constipation remedy “Fybogel”. Psyllium mucilage is also used as a natural dietary fiber for animals. The dehusked seed that remains after the seed coat is milled off is rich in starch and fatty acids, and is used in India as chicken feed and as cattle feed.
Psyllium mucilage possesses several other desirable properties. As a thickener, it has been used in ice cream and frozen desserts. A 1.5% weight/volume ratio of psyllium mucilage exhibits binding properties that are superior to a 10% weight/volume ratio of starch mucilage. The viscosity of psyllium mucilage dispersions are relatively unaffected between temperatures of 68 to 122°F, by pH from 2 to 10 and by salt (sodium chloride) concentrations up to 0.15 M. These physical properties, along with its status as a natural dietary fiber, may lead to increased use of psyllium by the food-processing industry. Technical-grade psyllium has been used as a hydrocolloidal agent to improve water retention for newly-seeded grass areas, and to improve transplanting success with woody plants.
