Scientists have also found it contains antioxidants that protect DNA damage that is linked to some cancers and it can alleviate stress to the body after energetic work outs.
Nicola Dodd, AHDB marketing manager, said the Instagram campaign had reached 120,000 people in month. “Social media is a great way to reach a young audience. Watercress has not caught up with recent health trends, for example kale and spinach, and is largely overlooked by the young. We want to inspire them to include it in their diet.”
Mr Amery added: “We are going to keep up the offensive by giving out free watercress in gyms. We are starting a pilot in Dorset by installing a fridge in gyms to keep watercress fresh before going nationwide. We are also going to target commuters at railway stations with bunches of watercress.
“In the 1920s watercress was sent by rail to cities across the country, sold by hawkers in streets and eaten on the hoof. In winter people were desperate for green veg and watercress was the only one available. Today it’s sold in supermarkets and costs from £1 to £1.40 a bag.”
Celebrity cook Mary Berry, who grew up on a farm with watercress beds, said recently "My favourite thing was watercress sandwiches with raspberry jam.”
A new generation of chefs is also now being enlisted to showcase watercress. Chris Wheeler, head chef at Stoke Park, Buckinghamshire, who has starred on TV’s Saturday Kithcn, Sunday Brunch and The Great British Menu, has created a pudding – a watercress, sweet yoghurt and coconut dome with raspberry centre, bitter chocolate shavings and watercress oil.
Watercress is mainly eaten in salads, sandwiches and soups but can be used in stir fries, smoothies, in pesto, chutney, salsa verde and sauces to accompany meat or fish.