In the UK, approximately one in five individuals experience vitamin D deficiency during the winter and spring seasons and globally, nearly one billion people are deficient in adequate vitamin D levels.
A growing issue, Vitamin D deficiency is linked to higher risk of cancer, mood disorders, dementia, and many leading causes of mortality. Studies have also shown that vitamin D insufficiency is linked to increased severity of infection by Covid-19. The prevalence isn’t uniform; people with darker skin, the elderly, pregnant women and people who tend to be confined indoors are more likely to be deficient.
Vitamin D, a fat-soluble vitamin, plays a crucial role in maintaining bone health, and supporting immune function to fight off infection and illnesses. Vitamin D helps the body absorb calcium and phosphorus which is important for building and maintaining strong bones, teeth and muscles.
Often called the ‘Sunshine vitamin’, Vitamin D is produced by the body, when the skin is exposed to ultraviolet B (UVB) light from the sun. In the UK, approximately 80 – 90% of our vitamin D is derived from exposure to light, with the remainder being supplemented from food. Foods rich in vitamin D include oily fish, red meat and egg yolks, but plants lack this essential vitamin.
The UK government recommends that everyone takes a daily 10µg vitamin D supplement between October and March, however reportedly uptake is low. Unlike countries such a the USA there is no mandatory Vitamin D food supplementation in the UK.
Sunshine tomatoes
Some plants, including tomato, make a precursor of vitamin D, called pro-vitamin D3 as an intermediary, which is then converted to compounds the plant uses for defence. Using gene editing, researchers at the John Innes Centre have managed to precisely tailor the genes in tomato plants so they accumulate very high levels of pro-vitamin D3 in the fruit and leaves.
Through biofortification of tomatoes to produce fruit containing high levels of vitamin D3, the researchers have potentially identified a solution to vitamin D deficiency. Ripe tomato fruit grown from gene edited plants produce 20% of the RDA of vitamin D, a similar amount to recommended food sources such as two medium sized eggs or 28g tuna. According to the researchers, the change in the tomato’s genetic makeup does not affect the appearance or growth of the plants, or their yield.
Tomato leaves, usually considered waste, also have the potential to be used as a source of vegan-friendly vitamin D3 for supplements. The leaves of edited plants contain up to 600 ug of provitamin D3 per gram of dry weight.
A patent for methods to produce biofortified Vitamin D enriched tomatoes has been filed and licensed.
ViTaL-D Study
Researchers at from the Quadram Institute, John Innes Centre and the University of Surrey are now investigating whether consuming biofortified tomatoes, enriched in vitamin D, can supplement vitamin D levels in the UK population during the winter months.
76 participants with low vitamin D levels have been enrolled in the ViTaL-D Study, funded by the Biotechnology and Biological Sciences Research Council (BBSRC). The participants, aged over 18 and living within 40 miles of Norwich, where the research is taking place, will consume a portion of tomato soup daily for three weeks. Research will then see if this leads to an increase in their blood of the active form of vitamin D that helps us stay healthy.
Professor Cathie Martin FRS, group leader at the John Innes Centre, said: “Food is health care – diet has a huge impact on the health of us all and vitamin D deficiency is a widespread problem both here in the UK and the rest of the world.
“It has been exciting to use cutting-edge science to enrich a food such as tomato with extra vitamin D3. In this first-of-its-kind trial we are exploring the impact this produce might have on our diets and health here in Norwich, using tomatoes grown in our glasshouses at the John Innes Centre. People often take vitamin supplements, but new breeding techniques mean that in the future this already healthy, fresh food that lots of people eat could be fortified with micronutrients from day one, with the potential to help boost the health of all of us.”
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.”
