One in 12 people will tuck into an entirely vegan or vegetarian Christmas Day meal this year and almost one in five hosts will be cooking for a vegan or vegetarian guest over the festive period, according to research.

As the flexitarian trend continues to sweep the UK, Britain’s supermarkets are rolling out their biggest range of festive vegan and vegetarian food yet, tempting shoppers to swap traditional turkey for exotic meat-free options like truffled cauliflower cheese en croûte, tacos stuffed with jackfruit and – as a Boxing Day palate-cleanser – “deli-style” thin-sliced celeriac.

Flexitarianism has been one of the most striking food trends of 2018, with one in three people trying to reduce their meat intake on health or ethical grounds, even if they don’t adopt strictly vegan or vegetarian diets.

Research from Tesco – the UK’s largest supermarket – reveals that the shift towards a plant-based diet shows no signs of slowing down, with 18% of consumers (not just Tesco shoppers) saying they will be catering for a vegan or vegetarian on Christmas Day.

Alternative “greener” Christmas dinners will even be more popular in 2018 than turkey’s famous rival, goose, which will be on the plates of just 4% of the nation.

In 2018, the demand for chilled and frozen vegan food at Tesco grew by more than 50%, helping to swell the UK’s meat-free market to £310m.

As a result, the grocer has doubled its range of vegan festive main dishes, and has also launched its first ever vegan party food and a Christmas vegan bubble and squeak sandwich.

In 2017 the retailer hired US-based chef and self-confessed “plant pusher” Derek Sarno as its first “director of plant-based innovation” to oversee the creation of its Wicked Kitchen vegan food label. Sarno has been sprucing up the grocer’s Christmas food and working with suppliers, farmers and chefs on developing new plant-based options.

Sarno reckons the days of vegans and vegetarians being “an afterthought at the Christmas dinner table” are over and he is particularly proud of his wafer-thin celeriac – pictured piled up in ribbons on his Instagram feed.

Waitrose is also forecasting a record flexitarian Christmas. Recent sales of its vegan party food range are up 20% since its October launch. Among its plant-based canapés are jackfruit tacos, together with “butternut squash’age” rolls and beet wellington – a vegan take onbeef wellington.

Shoppers are also cooking vegan Christmas recipes at home. Searches for “Christmas vegan” on the grocer’s website are up 225% compared to this time last year.

Even nut roasts – the most traditional vegan fare – have been given a makeover. Marks & Spencer has a butternut, almond and pecan version, while Morrisons is offering a festive cranberry and pistachio nut roast.

The supermarkets are preparing for the flexitarian trend to grow even faster next year and for more shoppers to choose to eat more plants as part of the January detox season, and in response to the Veganuary campaign, which urges people to try a vegan diet for the first month of the new year. Both Sainsbury’s and Marks & Spencer are planning to boost their vegan ranges in the new year.

Vegan cook Niki Webster – who launched her Rebel Recipes food blog in 2015 – has been working with Sainsbury’s to create simple recipes using vegan products likefaux mince made from pea protein.

She said: “Over the last few years there has been huge increase in vegan restaurants, cookbooks, products and the launch and expansion of vegan ranges within the retailers.”

Webster put the increase in plant food popularity down to a series of factors, including “environmental awareness, social media, high-profile vegans, campaigns such as Veganuary and people looking to reduce their meat consumption”.