Over the past couple of years, people have become especially interested in CRISPR gene editing and vitamin D. Both are linked to fighting off the infamous Covid-19 virus, but in different ways. CRISPR gene editing offers us avenues and technologies that can help us detect the genetic signature of this virus and understand it further so that we can better respond to it, while vitamin D deficiency is connected to an increase in autoimmunity and susceptibility to infection—neither of which are ideal when facing a contagious virus.

Human bodies can get vitamin D from sun exposure, but even so, many people are vitamin D deficient and should be trying to supplement their vitamin D supply with their diet. The problem is that there are very few vitamin-D-rich foods out there. However, researchers at the John Innes Center are on a mission to provide a new source of vitamin D through the power of genetic engineering.

The team chose to work with tomatoes, which are already known to naturally contain a vitamin D precursor called 7-DHC. However, this vitamin D precursor is found at low levels and only in the tomato leaves, which don’t usually make it to the plate.

To alter this, the researchers employed the CRISPR-Cas gene-editing system to turn off a specific enzyme in the tomato genome that, under normal circumstances, converts 7-DHC into other molecules. The new genetically modified tomatoes that lack this specific enzyme will now accumulate 7-DHC not just in the leaves but in the flesh and peel, and at much higher levels. Better yet, blocking this enzyme didn’t have any effect on the growth, development, or yield of the tomato plants.

The 7-DHC within the tomato is converted into vitamin D3 by exposing the fruit to UVB light. Once exposed, a single tomato was found to contain as much vitamin D as two eggs or 28 g of tuna. The vitamin D quantity will only increase if, for example, they were to dun-dry the tomatoes.

On top of making the tomato more nutritious, the team believes that the vitamin-D-rich leaves could be used to make supplements instead of going to waste as they usually do. The team has their eyes on other plants with the same biochemical pathways, such as eggplants and potatoes, as the same kind of gene-editing could be used to make them more nutrias as well.