Almost 100 million cups of tea are consumed daily in the UK. Meteoritka/Shutterstock

It’s not every day you find yourself standing in a tea garden in Devon, surrounded by rows of Camellia sinensis – the same plant species used to make tea in India, China and Japan. But there we were, in the heart of Dartmoor, picking fresh tea leaves from plants that are thriving in the UK’s cool, damp climate.

It’s a surprising sight, and one that could become more common. Britain may be known as a “nation of tea drinkers”, but might there be opportunities for it to increasingly be a nation of tea growers? Our research has involved working with growers in Devon and Wales to explore the chemistry of UK-grown tea.

We’re using a technique called “metabolomics” to understand what’s going on inside the leaves, and how different growing conditions, processing methods and even fermentation (like making kombucha) affect the final cup.

Tea competes with coffee to be the UK’s favourite drink, but almost all tea leaves are imported. With concerns about climate change, food security and sustainability increasing, there’s growing interest in whether more food, including tea, can be grown in the UK.

We chose mid-Wales and south-west England for our project because of their mild, wet climates, which are surprisingly well-suited to tea cultivation. Dartmoor, in particular, has a unique microclimate and varied soils that make it an ideal test site. There’s also a strong local appetite for sustainable farming and agricultural innovation.

Wales already has a tea pioneer in Lucy George, a Nuffield farming scholar who began growing tea near Cardiff in 2014. Her brand, Peterston Tea, is now sold in Welsh shops and around the world. She believes that slower growth in Wales’ cooler climate may actually improve flavour, making Welsh-grown tea more than just a curiosity.

Dr Amanda J Lloyd and Dr Ali Warren-Walker gathering samples at Dartmoor Estate Tea in Devon.
Aberystwyth University, CC BY

What we found

One of our studies used metabolomics and machine learning to explore the chemical diversity of UK-grown tea.

Metabolomics involves analysing the small molecules – known as “metabolites” – in a sample. These include sugars, amino acids and polyphenols, as well as more complex “bioactives” like catechins and flavonoids. These types of compounds influence flavour, aroma and potential health benefits.

We used method called “direct injection mass spectrometry” to create a chemical fingerprint of each sample. Then we used machine learning to spot patterns and differences. We also looked at how the chemistry of the leaves changes depending on the time of day they’re picked and how they’re processed.

Our findings show that tea grown in the UK has a rich and diverse chemical profile. Different varieties, picking times and processing techniques all influence the concentration of beneficial compounds like catechins and flavonoids.

The other study was a human trial, which found that drinking green tea from Dartmoor with rhubarb root for 21 days significantly reduced LDL (bad) cholesterol and total cholesterol, and without disrupting the gut microbiome. This suggests that UK-grown tea could be developed into a functional food, supporting health. This product is now being sold by a tea company in Carmarthenshire, west Wales.

This is exciting because it means we can tailor how we grow and process tea to enhance both its flavour and its health benefits. And it opens the door to a potential new UK-grown tea industry. It could play a part in supporting the rural economy, reduce reliance on imports and offer a more sustainable future for UK agriculture.

On a global level, this kind of research helps us understand how plants respond to different environments, which is crucial for food security in a changing climate.

A Cornish tea grower explains the challenges of growing tea in the UK.

What’s next?

We’re now investigating how different tea varieties and processing techniques – like steaming, oxidation and novel drying methods – influence the tea’s chemical make-up. These techniques could help preserve more of the beneficial compounds and make it easier to develop new tea-based products like powders or supplements.

Another human study is looking at how kombucha affects well-being, memory, inflammation and stress.

We’re also continuing to test how different varieties of tea respond to the UK’s conditions, and how we can refine growing and processing techniques to produce high-quality, health-promoting tea on home soil.

As climate change reshapes what we can grow and where, tea may just become one of the UK’s most unexpected and exciting new crops.

Amanda Lloyd receives funding from Welsh Government Covid Recovery Challenge Fund (part of the Welsh Government’s Food and Drink Division funding), alongside Innovate UK Better Food for all (10068218), and the Joy Welch Research Fund (Aberystwyth University internal)

Nigel Holt receives funding from Innovate UK Better Food for all (10068218)