Guar

Guar is an upright annual legume growing about 1 to 2 metres tall, with trifoliate leaves and clusters of small white to pink flowers. It forms slender pods, usually 5 to 12 cm long, in tight clusters along the stem. The seeds are small, hard, rounded and oval, typically pale grey, beige or dark, with a flattened side. The young green pods have a firm texture and a mildly bitter, grassy taste and are cooked as a vegetable. Mature seeds contain a large central endosperm that is milled to produce guar gum, an off-white powder. Seeds are sold dried, and guar gum is sold as a fine flour.

Guar is thought to have been domesticated in the Indian subcontinent from a wild relative, Cyamopsis senegalensis, which occurs in Africa, and cultivated for fodder and food for many centuries in the semi-arid regions of what is now India and Pakistan. The name guar is used in Hindi and related languages, and the word is often linked to a Sanskrit phrase meaning cow food, reflecting its traditional role as livestock feed. The genus name Cyamopsis comes from Greek words meaning bean-like, and tetragonoloba refers to the four-angled pods.

For most of its history guar was a local crop. Farmers in Rajasthan, Gujarat, Haryana and Punjab grew it as animal fodder and as a green manure that enriches soil with nitrogen, and the tender pods were cooked in village kitchens, often with spices, as a dry vegetable called gawar phali.

The modern importance of guar began in the twentieth century. During the Second World War, supplies of locust bean gum, a thickener used in industry, were disrupted, and researchers looked for alternatives. They discovered that the galactomannan in guar seeds could do the job, and the United States began trials of the crop and mills for processing it. After that, guar gum spread widely through food, textile, paper and mining industries.

In the 2010s, guar demand surged because the gum was used in hydraulic fracturing fluids for oil and gas extraction, causing prices to spike and affecting farmers in India. Prices later fell again as demand shifted. Today India remains the world's top producer, and guar illustrates how a humble desert legume can become globally traded.

In India and Pakistan the tender pods are chopped and stir-fried with spices, or cooked with lentils, and in Rajasthan they appear in the dish known as ker sangri-style vegetable mixes. Dried seeds are processed into guar gum, used as a thickener and stabiliser in ice cream, sauces, dressings, gluten-free baking, beverages and pet food. Outside food, it appears in paper, textiles, cosmetics, explosives and drilling fluids. The plant is also grown as forage and as a rotation crop in dry regions. Gum is added in tiny amounts, usually under one per cent of a recipe.

Guar gum is a soluble fibre. Clinical studies show that it can slow digestion of carbohydrates and modestly lower post-meal blood sugar and cholesterol, which is why partially hydrolysed guar is sold as a fibre supplement. The cooked pods provide fibre, vitamins and minerals as a vegetable. Evidence for weight loss from guar supplements is poor. Benefit depends on dose and form and should be discussed with a clinician for any medical purpose.