Britain’s grocers are going vegan in an attempt to keep up with their customers’ increasingly health-conscious food choices.

Waitrose this week launched dedicated vegan sections in more than 130 stores after increasing its vegan and vegetarian product range by 60%. Iceland is also rapidly expanding its vegan range after its meat-free No Bull burgers outsold their wagyu beef counterparts so far this year, while sales of its vegetable-based food have risen by 10% over the past 12 months.

Chloe Graves, who runs the vegan and vegetarian range at Waitrose, said the retailer had responded to customer demand after sales of vegetarian food rose by more than a third over the past year.

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She said: “It is just becoming more normal now to have a couple of days a week meat-free for environmental or health reasons.”

She said younger people were talking about veganism on social media, but Waitrose’s old shoppers were also keen to buy into the idea of being “flexitarian” – switching between vegetarian or vegan meals on some nights and eating meat on others.

The number of vegans in the UK, who shun all animal products including dairy and eggs, has grown fourfold in the past 10 years to about 550,000, according to the Vegan Society.

As celebrities including the Strictly Come Dancing winner Jay McGuiness and the actor Joanna Lumley line up to back World Meat Free week starting on Monday, market analyst Kantar has suggested 2018 is the year veganism goes mainstream. It says Britons ate 200m more meat-free meals last year while spending on meat substitutes such as Quorn rose by £30m year on year.

Veganism is carving out a niche on Instagram, and enjoys hipster cache at events such as London’s Vegan Nights and the weekly Hackney Downs market established by the influential blogger Sean O’Callaghan, AKA “the Fat Gay Vegan”. There have also been festivals dedicated to the trend at venues as far afield as Totnes in Devon and Inverness in Scotland.

Big chains such as Marks & Spencer, Tesco and Pret a Manger now push vegan ranges, and Pizza Hut recently joined Pizza Express and Zizzi in offering vegan pizzas. Last year Guinness went vegan and stopped using fish bladders in its brewing process, after two and a half centuries.

Tesco is reportedly working on a deal that could mean the meat-free Beyond Burger – a hit in the US – is stocked in its freezers this summer. It comes after the UK’s largest supermarket chain hired the US chef and self-proclaimed “plant pusher” Derek Sarno as its “director of plant-based innovation” to spearhead its vegetarian Wicked Kitchen range.

Neil Nugent, the head chef at Iceland, where he is helping the frozen food specialist tap into new trends, said the company hoped to launch more meat-free products in the autumn after finding over-50s were just as keen on the idea as young millenials.

“It has taken us all by surprise. Customers are saying can you do more,” he said. “I think the vegan and flexitarian market is the first major food trend that has come out of social media. Avocado was one thing but everyone is getting behind eating more veg.”