Gene-edited tomatoes that boost vitamin D could be on sale in England soon

Gene-edited tomatoes that boost vitamin D could be some of the first gene-edited crops available in England.

Researchers have found that the salad favourite can be engineered to produce more of a precursor to vitamin D3 by turning off a specific gene.

When exposed to UV light, this precursor – provitamin D3 – is converted to vitamin D3, the sunshine vitamin that so many people across globe do not have enough of.

Tomatoes naturally contain one of the building blocks of vitamin D in their leaves at very low levels, but this does not normally accumulate in ripe tomato fruits.

Researchers at the John Innes Centre in Norwich used gene editing to block a gene normally responsible for converting pro-vitamin D3 into cholesterol.

This led to the substantial accumulation of provitamin D3 in the tomatoes’ fruits and leaves, without affecting the growth, development or yield of the plant.

It comes as the government is set to introduce a bill on Wednesday to allow the commercial growing of gene-edited crops in England.

The technique is currently not used for food production in the UK, in line with EU law, but Brexit means the UK can set its own rules.

A new source of vitamin D

The tomatoes – which look and taste like regular tomatoes – could represent a new dietary source of vitamin D with potential public health implications, scientists say.

Data suggests that around one in five adults and one in six children do not have enough vitamin D.

The body creates vitamin D after the skin is exposed to UVB light, but the major source is food.

Experts suggest this new biofortified crop could help millions of people with vitamin D insufficiency, a growing issue linked to higher risk of cancer, dementia, and many leading causes of death.

“We’ve shown that you can biofortify tomatoes with provitamin D3 using gene editing, which means tomatoes could be developed as a plant-based, sustainable source of vitamin," Professor Cathie Martin, who led the study, said.

“Forty percent of Europeans have vitamin D insufficiency and so do one billion people world-wide.

“We are not only addressing a huge health problem, but are helping producers, because tomato leaves which currently go to waste, could be used to make supplements from the gene-edited lines.”

Tomato leaves are usually waste material, but those from the edited plants could be used for the manufacture of vegan-friendly vitamin D supplements, or for food fortification, the researchers suggest.

First author of the study Dr Jie Li said: “The Covid-19 pandemic has helped to highlight the issue of vitamin D insufficiency and its impact on our immune function and general health.

“The provitamin D enriched tomatoes we have produced offer a much-needed plant-based source of the sunshine vitamin.

“That is great news for people adopting a plant-rich, vegetarian or vegan diet, and for the growing number of people worldwide suffering from the problem of vitamin D insufficiency.”

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The recommended daily intake of vitamin D is 10 micrograms for adults.

Researchers suggest eating just two of the new tomatoes could make up for the gap between how much vitamin D people in the UK are consuming, and how much they need.

They also found that the amounts of provitamin D3 in one tomato fruit — if converted to vitamin D3 — would equal levels present in two medium-sized eggs or 28 grams of tuna.

Explaining why these tomatoes might be a better alternative to vitamin D supplements, Prof Martin said people would also benefit from the other nutrients of the fruit, including fibre.

The study indicates that vitamin D in ripe fruit might be increased further by extended exposure to UVB, for example during sun-drying.

According to the researchers, exposing the plants to natural UVB light – from the sun – may be a more sustainable and effective way to grow them.

The tomatoes are expected to ripen one month later, however it could yet be sometime before the edited crop is ready to go to market.

Researchers suggest the change can be engineered into any tomato variety, and could probably work well in other solanaceous food crops such as peppers, chillis, potatoes and aubergines.