Media playback is unsupported on your device Media caption Is coconut the cream of the milk stars?

The trend towards healthy eating was evident in the latest results from UK sandwich chain Pret A Manger.

It said that coconut was its "most popular" new ingredient, with coconut porridge selling particularly well.

The sandwich chain reported a 15% rise in sales to record £776m, while its measure of profit hit a record £93m.

Last year, Pret opened its first vegetarian store and the best-selling items from that shop are now sold in all its outlets.

Pret's menu reflects changes in the nation's eating habits.

According to research firm Kantar Worldpanel, for supermarkets, these grocery items were among the fastest-selling last year:

Flatbread, up 196%

Avocado, up 33%

Halloumi, up 29%

Quark (a type of cheese), up 27%

Spinach, up 26%

Fraser McKevitt, a retail analyst at Kantar Worldpanel, says those items reflect two trends.

The first is generally to eat more healthily, so more spinach and avocado is on the menu. The second is the growth in people eating more vegetarian-style food, but not necessarily going full vegetarian, hence the growth in halloumi and quark cheeses, he said.

And those trends are not just seen among young, metropolitan types.

"Everybody is trying to watch what they eat," Mr McKevitt said. "The people most concerned about health tended to be older shoppers and consumers."

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While coconut products have not made it on to Kantar's list of fast-growing groceries, Waitrose says they have become a favourite with its customers.

"Coconut oil, water and milk have now become part of many customers' regular weekly shopping baskets," Waitrose said.

It has identified coconut flour as one of its key food trends.

For Pret, coconut milk sales now exceed soya milk, while porridge made from coconut milk now accounts for 20% of its porridge sales.

Great grains

Waitrose says that grains are also "hugely popular", particularly in bread, as well as salads.

"We're using chia seeds in a couple of our wraps, and we've got grains going in our open sandwiches," says Michelle Gibbs, who oversees Waitrose sandwiches.

Pret also last year introduced dairy-free products including a range of soups, which were also free from gluten.

But it's not all nuts and grains. The most popular item at Pret remains the croissant, with 16 million sold last year.