Psyllium

Psyllium has been used as a thickener in ice cream and other 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.[6] 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.[6] Psyllium seed husks can also be used to improve texture in gluten-free baked goods, to bind meatballs, and to thicken sauces.[7] Some people use them to manage symptoms of irritable bowel syndrome, or to maintain a clean colon for receiving anal sex.[7]

Dietary supplements containing psyllium are sold mainly to aid weight loss, although there is little scientific evidence for such effects.[8]

Psyllium is mainly used as a viscous, soluble dietary fiber that is not absorbed by the small intestine.[9] The purely mechanical action of psyllium mucilage is to absorb excess water while stimulating normal bowel elimination. Although its main use has been as a laxative, it is more accurately regarded as a dietary fiber and as such can help reduce the symptoms of both constipation and mild diarrhea.[9] The laxative properties of psyllium are attributed to the fiber: it absorbs water and subsequently softens the stool.[9] It increases flatulence (gas) to some degree.[10]

In 1998, the U.S. Food and Drug Administration approved a health claim on food labels for dietary psyllium as a soluble fiber – if consumed regularly – that would reduce the risk of heart disease by lowering blood cholesterol.[11] Clinical research demonstrated that seven grams or more per day of soluble fiber from psyllium seed husk would sufficiently lower total cholesterol and low density lipoprotein cholesterol in people with hypercholesterolemia, two accepted biomarkers for risk of coronary heart disease.[12] The findings were later confirmed in a meta-analysis that incorporated more evidence.[13] To be eligible for the FDA-allowed health claim, one serving of a manufactured food or dietary supplement must contain at least 1.7 g of psyllium as soluble fiber.[11] Whole oats, barley and foods containing beta-glucan soluble fiber were included as eligible sources for the label claim.[11]

In 2014, the U.S. Food and Drug Administration approved a qualified health claim for psyllium as a possible benefit for people with diabetes, requiring FDA-approved wording on a product label: "Psyllium husk may reduce the risk of type 2 diabetes, although the FDA has concluded that there is very little scientific evidence for this claim."[14] A meta-analysis published after the FDA decision reported that psyllium provided before meals improved fasting blood glucose and glycated hemoglobin, but that the larger effect was seen in people diagnosed with and being treated for type 2 diabetes, and only a modest improvement for people classified as pre-diabetic.[4]

Psyllium has been found by meta-analysis of clinical trials to significantly reduce blood pressure in people suffering from hypertension.[15] Psyllium has not been shown to have the same effect on individuals with normal or elevated blood pressure.[15]

Psyllium fiber dietary supplements are used in veterinary medicine to treat sand impaction in horses to aid in elimination of sand from the horse's colon.[16]

Psyllium can cause allergic reactions, including anaphylaxis.[21] Psyllium may act as a potent inhalant allergen capable of eliciting asthma symptoms.[22] Health care professionals at geriatric care hospitals, who are frequently exposed to psyllium in the laxatives administered to patients, are commonly IgE sensitized to psyllium (13.8%), and 8.6% have clinical allergy to psyllium.[23] Pharmaceutical manufacturing employees who have been exposed to psyllium during the processing have developed occupational asthma and IgE sensitization.[24] In order to protect sensitized workers, psyllium has an extremely low occupational exposure limit of 150 ng/m³.[25]

Introduced in 1934 by G.D. Searle & Company, Metamucil was acquired by Procter & Gamble in 1985. The name is a combination of the Greek word for change (meta) and the class of fiber that it utilizes (mucilage). In its early years, Metamucil achieved sporadic drug-store distribution as a "behind the counter" product - sold in pharmacies but not on the shelf, so that the pharmacist may counsel the purchaser on correct usage. Since 1974, the brand was also marketed to consumers by print and TV advertising and became available in food outlets. Flavored versions were added in 1979.

The brand is sold as powdered drink mixes, capsules and wafers in a variety of flavors. Metamucil contains psyllium seed husks as the active ingredient. It is manufactured in Phoenix, Arizona, by Procter & Gamble.[27] When first marketed to consumers in 1974, Metamucil was marketed as a laxative. The advertising slogan at that time was "If not nature, then Metamucil". Procter & Gamble sought to make Metamucil a household name by advertising in magazines and on television, using the claim "All fiber is not created equal".[28]