It is green, slimy, and currently the food favoured by those on a mission to be slender. With Victoria Beckham reportedly encouraging her fellow Spice Girls to knock back a seaweed-based shake each morning, to help them get into shape for their forthcoming tour, and with “macrobiotic” dieters such as Madonna and Cindy Crawford consuming it by the bucketful, the sea vegetable has become inextricably linked with svelteness in celebrity circles. But even scientists agree that it could be more than the latest fad.

Japanese researchers recently identified seaweed as an unlikely weapon in the war against obesity. They found that rats given fucoxanthin – a pigment in brown kelp – lost up to 10% of their body weight, mainly from around their midriffs. This led researchers to believe that the pigment could be developed into a slimming pill.

Although brown kelp is a key ingredient of Japanese miso soup, the researchers at Hokkaido University say that drinking large quantities in an effort to shed pounds won’t work, as the active ingredient is not easily absorbed in its natural form. However, they reckon a seaweed slimming supplement should be available within three years.

Others are convinced that kelp can keep fat cells at bay, and not just because it contains almost no fat and is low in calories – a sheet of nori seaweed, the type used in sushi, contains just 12.5. Jeff Pearson, a professor of molecular physiology at the University of Newcastle, says that a seaweed extract called alginate could help people with weight problems. “Some of the existing obesity pills work by inhibiting the enzyme lipase, which digests fat; but the fat is diverted into the colon, where it is digested by bacteria, causing bloating,” he says. “Alginates from seaweed also inhibit this enzyme, but they don’t produce the same adverse side effects.”

While seaweed diet pills are on the horizon, Yvonne Bishop-Weston, principal nutritionist at the Foods for Life clinic, on Harley Street, says she recommends that her clients drink seaweed shakes. Seaweed is a rich source not only of antioxidants, vitamins B1 (important for maintaining nerve function and keeping muscle tissue healthy), B2 (which helps the body to absorb iron) and B12, but of iodine. “Iodine is needed for the thyroid gland to function properly,” she says. “Since the thyroid gland controls the metabolic rate of every cell in the body, too little iodine in the diet can mean your body struggles to burn calories efficiently.”

For those not prepared to fork out upwards of £50 a month for a commercial seaweed product, there are other ways to boost your algae quota. Martha Roberts, a nutritional therapist based in London, recommends laver bread, the traditional Welsh dish made from laver, a purple seaweed found around the rocky shores west of Swansea. It is prepared by washing and boiling the seaweed until it becomes a jelly, which is then mixed with oatmeal, shaped into patties and cooked. If you want to collect your own, autumn is the best time to harvest it – wash it well and simmer in a tiny amount of water for about 10 hours.

“You can now buy pies containing lentils and seaweed as an alternative to meat pies,” Roberts says. “Or you could just visit Yo! Sushi more often.”

A wide range of seaweed products is available from Orkneyseaweed.co.uk and Dolphinseaveg.com. Seaweed is also available from specialist oriental shops and most supermarkets.

One month’s supply of Progreens seaweed and algae shake costs £36 from Foods for Life; 020 7637 8436, foodsforlife.org.uk

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