The UK research team detail how they engineered provitamin D3 accumulation in the tomato by turning off a specific molecule in the plant’s genome increasing the vitamin in both the fruit and leaves of tomato plants. It was then converted to vitamin D3 via exposure to UVB light.
“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 D3,” explains Professor Cathie Martin, corresponding author of the study which appears in Nature Plants.
“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.”
The John Innes Centre team used CRISPR-Cas9 gene editing to revise the genetic code of tomato plants so that provitamin D3 accumulated in the tomato fruit.
The leaves of the edited plants contained up to 600 ug of provitamin D3 per gram of dry weight. The recommended daily intake of vitamin D is 10 ug for adults.
Waste material from the edited plants could be used for the manufacture of vegan-friendly vitamin D3 supplements, or for food fortification, the team adds.
UK Government review
In April, the UK Government announced an official review to examine whether food and drink should be fortified with vitamin D to address health inequalities.
The review calls on the public, experts, industry and patient groups for ‘innovative ways’ to boost vitamin D levels especially among Black and South Asian communities, where levels of the vital vitamin are generally lower.
Most foods contain little vitamin D and plants are generally very poor sources. Vitamin D3 is the most bioavailable form of vitamin D and is produced in the body when the skin is exposed to sunlight.
In winter and in higher latitudes people need to get vitamin D from their diet or supplements because the sun is not strong enough for the body to produce it naturally.
Commenting on the findings, Guy Poppy, Professor of Ecology at the University of Southampton, said: “Vitamin D deficiency affects 1 billion people and causes wide ranging health impacts ranging from cancer to cardiovascular disease.
“For those living in Northern Hemisphere (less sunny climates), it is hard to get Vitamin D from sunlight and we need it from our diet or supplements.
“Using the recently approved technique of gene editing, this is an important breakthrough especially for those people eating more plant-based diets – most Vitamin D is found in meat and dairy foods.
“Gene-editing tomatoes to accumulate provitamin D3 at levels above recommended dietary guidelines could result in better health for many especially as tomatoes are a widely accessible and readily eaten food.
“This exciting discovery not only improves human health but contributes to the environmental benefits associated with more plant-based diets – often linked with a challenge in securing some key vitamins and minerals widely found and bioavailable in animal products.”
Fruit or supplement
Dr Penny Hundleby, Senior Scientist at the John Innes Centre, who was also not involved in the research, said “This is a beautiful piece of work that demonstrates how GE can be used to provide consumers with a plant-based source of Vitamin D, either by consuming the fruit itself or as a supplement that makes use of the waste products of tomato production (the leaves).
“In a time when sadly more of us are spending increasing time indoors, covering up more when we do go outside/ and simply not spending enough time outside to generate our own sunshine vitamins, this product offers consumers a vegan friendly plant-based source of Vitamin D.”
“With food security, sustainability and climate change high on the agenda – making the foods we grow and eat as nutritious as possible, while also reducing waste, supports these goals.”
First author of the study Dr Jie Li adds the Covid-19 pandemic helped to highlight the issue of vitamin D insufficiency and its impact on 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.”
Source: Nat. Plants
Published online: doi.org/10.1038/s41477-022-01154-6
“Biofortified tomatoes provide a new route to vitamin D sufficiency.”
Authors: Li, J. et al.