Seaweed is swimming its way into mainstream food markets in the UK. High-end supermarket chain Waitrose announced recently that it would stock fresh seaweed, after sales of the green food soared by 125% when Jamie Oliver claimed it had helped him to lose weight."Seaweed is one of this year's biggest trends in vegetables which we're seeing on menus of some of London's top and most creative restaurants," said Waitrose product developer Simona Cohen Vida."Our customers like to experiment in the kitchen and we predict that seaweed will top shopping lists this spring."A staple in people's diets in ancient times, seaweed has become popular not just because of its delicious flavour, but also because of its many health benefits.A study conducted in 2010 by scientists at Newcastle University found that the super food can reduce the rate of fat absorption by as much as 75%.It is a staple in Japanese cooking, where the obesity rate is about a tenth of that in the US.Chef Rene Redzepi's Instagram is full of meals using vitamin-rich seaweed, a popular addition to salads. Seaweed is also super-rich in iodine, a nutrient not found in many other foods, while some varieties are also high in protein and vitamins A and C...