Agar Agar

Agar agar (often labeled simply "agar" or E406) is a gelling polysaccharide extracted from certain red seaweeds, primarily species of Gelidium and Gracilaria. It forms a firm, heat-stable gel at low concentrations and is used in desserts, jellies, vegan cheeses, and laboratory media.

Chemically, agar is composed mainly of agarose and agaropectin — dietary fibers that humans do not digest. Because of this, agar contributes very little usable energy in typical culinary amounts and passes largely intact through the small intestine to the colon, where it can be partially fermented by gut bacteria.

Digestion and bowel effects

In modest amounts (e.g. a few grams set into a dessert), agar has little noticeable effect on most people. Used at higher concentrated or supplemental doses — for example in fiber supplements or older weight-loss preparations — agar can bulk and soften stool and promote bowel movements, and can also cause bloating or gas. There is a documented risk of esophageal or intestinal blockage when concentrated bulk-forming fiber is taken with inadequate fluid, particularly in people with swallowing difficulties, strictures, or a history of bowel obstruction; adequate water intake is essential when using agar therapeutically.

Use and tolerance

For cooking, agar is generally well tolerated and is a useful vegan and vegetarian alternative to gelatin, which is animal-derived. People with confirmed seaweed allergies are an exception and should avoid it. Those with swallowing difficulties, esophageal narrowing, motility disorders, or a history of bowel obstruction should be cautious with concentrated agar supplements and check with a clinician first.