Latin name: Cyamopsis tetragonolobus
Family: Fabaceae (Leguminosae)
Common names: Guar, Guar gum
Synonyms: C. tetragonoloba, C. psoraloides
A food, which may result in allergy symptoms in sensitised individuals.
Allergen ExposureGeographical distribution
This gummy substance, obtained from the ground endosperm of the seeds of a tree, is used mainly as a thickener and stabiliser in commercial food processing. Three or 4 species of Guar are found in regions of Africa, Arabia, India, Pakistan, the USA, and northern Australia (1).
Guar gum, available as a yellowish-white powder, has 5-8 times the thickening power of starch, and the unique ability among gums to hydrate rapidly in cold water. (But it is insoluble in oils, grease, hydrocarbons, ketones, and esters.)
Guar gum is an emulsifier, a firming agent, a formulation aid, a stabiliser, and a thickener. It is used in baked goods and baking mixes, cereals, beverages, cheeses and other milk products, dairy product analogues, fats, oils, gravies, jams, jellies, sauces, soup mixes and soups, syrups, toppings, vegetable juices, processed vegetables and deep-frozen foods. The gum functions synergistically with xanthan gum to increase the viscosity of a product. Guar gum is also common in fat-reduced or fatless spreads.
Guar gum increases viscosity in the gut, which causes a slower absorption rate of carbohydrates and stimulates bile production. This initiates cholesterol reduction and increases intestinal tract motility. It can also function as a slimming aid, since it swells in the stomach and gives a feeling of satiety.
There are many unexpected exposures, especially in the manufacturing industry. See under IgE-mediated reactions.
No allergens from this plant have yet been fully characterised.
Guar gum and Carob bean flour are both derived from Leguminosae plants. The molecular structures of Carob bean and Guar gum are very similar, consisting of a high-molecular-weight polysaccharide (a galactomannan, composed of galactan and mannan units, with a ratio of 1:4 for Carob and 1:2 for Guar) (2).
An extensive cross-reactivity among the different individual species of the genus could be expected but in fact is not seen frequently (3). In an in vitro study, the specific IgE binding by protein extracts of 11 food legumes was examined by RAST and AST inhibition. Cross-allergenicity was demonstrated to be most marked among the extracts of Peanut, Garden pea, Chick pea, and Soybean (4-5). However, clinical studies have found that there is little cross-reactivity among members of the Fabaceae (Leguminosae) (6-8).
Clinical ExperienceIgE-mediated reactions
Guar gum is a high-molecular-weight agent that can cause occupational rhinitis and asthma and may uncommonly induce symptoms of food allergy in sensitised individuals (9). Food-induced anaphylaxis has been reported (10-11).
Workers in textile, cosmetics, and fireworks manufacturing, the food and pharmaceutical industries, hairdressing, printing, and mining are at risk for occupational allergy. Allergic rhinitis and palateal oedema were reported in 3 individuals. Two were exposed to fine Guar gum powder upon opening cables in a power cable laboratory. (Guar gum is used as an insulator in rubber cables.) After 1-2 years' exposure, the patients developed rhinitis. The 3rd subject developed allergic rhinitis from exposure to Guar gum in a paper factory after 2 years' exposure. Skin-specific IgE to Guar was detected, and nasal provocation tests confirmed the diagnosis (12).
Rhinitis and asthma have also been reported in staff working in a pharmaceutical company and at a carpet manufacturing plant. Specific IgE was demonstrated on skin tests, and high levels were found in their serum to Guar gum. Specific inhalation challenges in which the 3 subjects were exposed to powder of Guar gum elicited isolated immediate bronchospasm in 2 subjects and an immediate and a delayed reaction in the 3rd subject (13).
Other studies have substantiated Guar gum as an occupational allergen in carpet manufacturing. Fourteen of 162 employees at a carpet manufacturing plant using Guar gum were shown to be sensitised to this gum, 2 of which had occupational asthma. Skin-specific IgE to Guar gum was demonstrated in 8 workers (5%), and 11 (8.3%) were found to have specific IgE to Guar gum in their blood (14). Other studies in printers and carpet manufactures have had similar findings (15).
In 15 subjects with occupational asthma—8 due to high-molecular-weight agents (flour and Guar gum) and 7 due to isocyanates—inhaling occupational agents of high or low molecular weight through the mouth or nose resulted in asthmatic symptoms. Significant nasal symptoms and an increase in nasal resistance occurred, as well as significant changes in inflammatory cells and mediators (16).
Sixteen workers with normal nonspecific bronchial reactivity (NSBR) who had been previously diagnosed with occupational asthma caused by high-molecular-weight agents—flour in 7 workers, psyllium in 5, and Guar gum in 4—were re-challenged after removal from exposure to these agents for a mean of 5-7 years. They no longer showed evidence of asthma and had a normal lung function. The authors conclude that specific bronchial reactivity to high-molecular-weight agents persists in most cases despite a normalisation of NSBR, and that this persistence is associated with a persistence of specific immunisation to the agent (17).
Reversible obstructive sleep apnoea as a result of occupational exposure to Guar gum powder in a pet food plant employee has been reported. Severe cough, rhinitis, and conjunctivitis were also experienced (18).
Baker’s asthma as a result of exposure to Guar gum has also been reported (19).
Excess intake of Guar gum may result in nausea, flatulence, abdominal cramps, and diarrhoea. Guar gum readily absorbs water and swells, and should thus not be ingested as a dry powder. There is a limit on the use of Guar gum in slimming capsules, since it could cause oesophageal obstruction as a result of swelling up in the oesophagus rather than the stomach, causing choking or even rupture of the oesophagus.
Guar gum is used as a thickener in foods and infant foods. The ingestion of Carob bean gum caused a significant reduction in the absorption and bioavailability of calcium, iron, and zinc (20).
Pharmacobezoars, bezoars comprised of medications, are unusual occurrences, but may occur as a result of Guar gum ingestion (21).
- Steger A, Radon K, Pethran A, Nowak D Sensitization and lung function in workers occupationally exposed to natural thickening products. Allergy 2000;55(4):376-81
- van der Brempt X, Ledent C, Mairesse M. Rhinitis and asthma caused by occupational exposure to carob bean flour. J Allergy Clin Immunol 1992;90(6 Pt 1):1008-1010
- Yman L. Botanical relations and immunological cross-reactions in pollen allergy. 2nd ed. Pharmacia Diagnostics AB. Uppsala. Sweden. 1982: ISBN 91-970475-09
- Barnett D, Bonham B, Howden ME. Allergenic cross-reactions among legume foods--an in vitro study. J Allergy Clin Immunol 1987;79(3):433-8
- Bardare M, Magnolfi C, Zani G. Soy sensitivity: personal observation on 71 children with food intolerance. Allerg Immunol (Paris) 1988;20(2):63-6
- Bernhisel Broadbent J, Sampson HA. Cross-allergenicity in the legume botanical family in children with food hypersensitivity. J Allergy Clin Immunol 1989;83:435-440
- Bernhisel-Broadbent J, Taylor S, Sampson HA. Cross-allergenicity in the legume botanical family in children with food hypersensitivity. II. Laboratory correlates. J Allergy Clin Immunol 1989;84(5 Pt 1):701-9
- Eigenmann PA, Burks AW, Bannon GA, Sampson HA. Identification of unique peanut and soy allergens in sera adsorbed with cross-reacting antibodies. J Allergy Clin Immunol 1996;98(5 Pt 1):969-78
- Raitala R, Kalimo K. Guar gum allergy. [Finnish] Duodecim 1990;106(10):829-30
- Moneret-Vautrin DA, Kanny G. Food-induced anaphylaxis. A new French multicenter survey. [French] Ann Gastroenterol Hepatol (Paris) 1995;31(4):256-63
- Moneret-Vautrin DA, Kanny G. Food-induced anaphylaxis. A new French multicenter study. [French] Bull Acad Natl Med 1995;179(1):161-72, 178-84; discussion 173-7
- Kanerva L, Tupasela O, Jolanki R, Vaheri E, Estlander T, Keskinen H. Occupational allergic rhinitis from guar gum. Clin Allergy 1988;18(3):245-52
- Lagier F, Cartier A, Somer J, Dolovich J, Malo JL. Occupational asthma caused by guar gum. J Allergy Clin Immunol 1990 Apr;85(4):785-90
- Malo J Luc, Cartier A, L'Archeveque, et. Al. Prevalence of occupational asthma and immunological sensitisation to guar gum among employees at a carpet manufacturing plant. J Allergy Clin Immunol 1990;86:562-569
- Quirce S, Sastre J. Occupational asthma [Review]. Allergy 1998;53:633-641
- Desrosiers M, Nguyen B, Ghezzo H, Leblanc C, Malo JL. Nasal response in subjects undergoing challenges by inhaling occupational agents causing asthma through the nose and mouth. Allergy 1998;53(9):840-8
- Lemiere C, Cartier A, Malo JL, Lehrer SB. Persistent specific bronchial reactivity to occupational agents in workers with normal nonspecific bronchial reactivity. Am J Respir Crit Care Med 2000;162(3 Pt 1):976-80
- Leznoff A, Haight JS, Hoffstein V. Reversible obstructive sleep apnea caused by occupational exposure to guar gum dust. Am Rev Respir Dis 1986;133(5):935-6
- Von Jorde W, Heyer N, Schata M. Baking additives as occupational allergens. Allergologie 1986;9:522-524
- Bosscher D, Van Caillie-Bertrand M, Deelstra H. Effect of thickening agents, based on soluble dietary fiber, on the availability of calcium, iron, and zinc from infant formulas. Nutrition 2001;17(7-8):614-8
- Stack PE, Thomas E. Pharmacobezo