One in three Britons drink plant-based milk, according to a report that suggests they have become a mainstream choice for consumers.

Shoppers spent £100m more in 2020 on alt-milks, made from oats, almonds or soya, turning it into a near £400m-a-year market.

The research, from Mintel, said 32% of those polled drank plant-based milk, which was up from 25% in 2020. The uptake is even higher among 25- to 44-year-olds at 44%.

Amy Price, a senior food and drink analyst at Mintel, said demand for alt-milk was being driven by environmental and health considerations.

That almost a third of adults were consuming plant-based milk was “evidence of its firmly mainstream status and appeal far beyond the vegan or vegetarian populations”, she added.

A quarter of the 2,000 people polled said the pandemic had made eating vegan or plant-based food and drink more appealing to them. For the under-35s that figure rose to 38%.

The report also revealed that oat milk had become the plant-based milk of choice, overtaking almond to become the biggest seller in 2020.

Shoppers spent £146m on oat milk in 2020, up from £74m in 2019. By contrast, consumers spent £105m on almond milk up slightly from £96m.

The rise of oat milk can be laid at the door of the fashionable Swedish brand Oatly, which has enjoyed runaway success thanks to a combination of quirky marketing and good timing.

It listed on the US stock market this year and is using the cash raised from investors to open factories, including a large site in Peterborough, East Anglia.

Price said oat milk was the main beneficiary of the growing interest in plant milks, with sales also boosted by new barista-style varieties that could be foamed and used to make popular coffees such as cappuccinos.

Overall, the total spend on plant-based milk reached £394m in 2020, up 32% on 2019. Nonetheless cow’s milk remains a far bigger market, worth more than £3bn.

The average person’s milk consumption in the UK has fallen 50% since the 1950s, however it soared on the back of pandemic lifestyle changes, with sales up by £100m to £3.2bn.