Guar gum

Guar gum (E412) is a galactomannan polysaccharide derived from the endosperm of the leguminous plant Cyamopsis tetragonoloba, grown primarily in India and Pakistan. Its molecular structure — a mannose backbone with galactose side chains at approximately a 2:1 ratio — creates a highly branched, water-soluble polymer that forms viscous solutions at low concentrations through extensive hydrogen bonding and physical chain entanglement. At 0.5–1.0% concentration in water, guar gum produces a viscosity of 4,000–6,000 mPa·s, making it one of the most efficient hydrocolloid thickeners available per unit mass. It is used in ice cream (preventing ice crystal growth), baked goods (improving moisture retention and crumb texture), dairy products, sauces, soups, salad dressings, and gluten-free products where it partially substitutes for gluten's visco-elastic network.

JECFA assigned guar gum a not-specified ADI, recognising it as a non-digestible polysaccharide that passes through the gastrointestinal tract without systemic absorption at normal food use concentrations (evaluated 1984). In the colon, guar gum is fermented by microbiota to short-chain fatty acids — a prebiotic effect that is nutritionally beneficial and does not contribute to caloric intake. At very high doses (>10 g per serving as used in some weight-loss products in the 1990s), guar gum can expand considerably upon hydration and caused oesophageal obstruction in several documented cases, leading to withdrawal of concentrated guar gum tablets from the US market by the FDA in 1992. At normal food additive use levels this risk does not exist.

Guar gum is authorised under EU Regulation (EC) No 1333/2008 at specified maximum levels and at quantum satis in many food categories. It holds GRAS status in the United States under FDA 21 CFR §184.1339. As a galactomannan with high-viscosity gel-forming capacity, guar gum contributes to satiety when consumed in food and has been studied as a dietary supplement for glycaemic management, with clinical evidence supporting modest reductions in postprandial blood glucose responses. It is one of the few food additives with both a functional role for manufacturers and documented physiological benefits for consumers.