Seed and husk
Dietary fiber, muscilage, and lowering cholesterol
Psyllium /ˈsɪliəm/, or Ispaghula /ˌɪspəˈɡuːlə/, 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 and India. Plantago seed, known commercially as black, French, or Spanish psyllium, is obtained from P. psyllium L., also known as P. arenaria. Seed produced from P. ovata is known in trading circles as white or blonde psyllium, Indian plantago, or Isabgol. Isabgol, (or Ispaghol in Pakistan) the common name in India for P. ovata, comes from the Persian words asp andgul, meaning "horse flower," 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 Washington state.
Health effects of dietary psyllium
Several studies point to a cholesterol reduction attributed to a diet
that includes dietary fiber such as psyllium. Research published 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. 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.
Choking is a hazard if psyllium is taken without adequate water as it thickens in the throat (see Psyllium seed husks). Cases of allergic reaction to psyllium-containing cereal have also been documented.
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 and as such can help reduce the symptoms of both constipation and mild diarrhea. The laxative properties of psyllium are attributed to the fiber absorbing water and subsequently softening the stool. It is also one of the few laxatives that does not promote flatulence.
Psyllium is produced mainly for its mucilage content. 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 about 25% (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.
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 as chicken and 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 20 and 50 °C (68 and 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.
It is suggested that the isabgol husk is a suitable carrier for the sustained release of drugs and is also used as a gastroretentive carrier due to its swellable and floatable nature. The mucilage of isabgol is used as a super disintegrant in many formulations.