The pictures on Instagram show bowls of fresh-looking caprese salad, with hunks of mozzarella, green basil, and vibrant tomatoes; red, yellow, and vivid purple. One of these tomatoes is not like the others. The purple tomato, from Norfolk Healthy Produce, gets its deep purple colour from high levels of anthocyanins in the fruit; the same chemicals are responsible for the lustrous hues of purple aubergines and blueberries.
At the moment, the purple tomato is only available in the USA. Yet its roots are found in East Anglia.
The health benefits of anthocyanins have been known for some time – hence the marketing term “superfoods” for many of the fruits and berries which contain high levels. Professor Cathie Martin, from the world-leading John Innes Centre in Norfolk, has long had research interests in applying plant sciences to improve human health. In 2008, Prof Martin and collaborators published an article describing a technique to engineer substantial anthocyanin accumulation in tomato fruit. While commercial tomato cultivars do not produce anthocyanins in the fruit, they nevertheless retain the genes to synthesise them. By inserting genes coding for transcription factors which control anthocyanin production from the snapdragon plant into the tomato genome, Prof Martin found that it was possible to “switch on” high levels of anthocyanin production in the tomato fruit.
Even more excitingly, a pilot test showed that cancer-susceptible mice given a diet supplemented with the high-anthocyanin tomato had an extended lifespan compared with control mice fed with normal tomatoes.
The healthy purple tomato was born.
However, the question of how to make these tomatoes available to consumers remained to be addressed. A spin-out company from the John Innes Centre and The Sainsbury Laboratory was launched, Norfolk Plant Sciences Ltd, with the aim of commercialising this and other agricultural research – the company describes itself as “the UK’s first GM crop company”.
The attitude towards GMOs in Europe, with many consumers being reluctant to accept such foods, and regulators being reluctant to grant licences for cultivation, meant that the purple tomato had to look elsewhere for approval. A US-based company, Norfolk Healthy Produce, was established to bring the tomato to market. Under US legislation, companies may take part in a voluntary consultation with the US FDA prior to marketing a food product from a new plant variety. Norfolk Healthy Produce did this, and in 2023 the consultation concluded that the engineered tomato raised no different risks from conventionally-bred tomatoes, and that – other than the increased levels of anthocyanins – were nutritionally similar. Likewise, approval for cultivation in the US was obtained from the USDA in 2022. This paved the way to the commercial launch.
Norfolk Healthy Produce have adopted a two-pronged approach to commercialisation, intended to help overcome any residual concerns that consumers may have over using bioengineered foods. One is to partner with commercial growers, to get punnets of the purple tomato into select stores. This goes alongside the aforementioned Instagram posts and other media images; trading on the stunning appearance of the tomato. Branding the tomato as “Empress” also leans into the purple colour.
The second commercialisation route, however, appears unique – seeds and seedling plants are now for sale direct to consumers, giving individuals the chance to cultivate their own GMO variety in their back garden. This eschews the more typical route of restricting seed sales, and appears designed to allow consumers to feel involved with growing their own crop, while also reassuring them that the plant is just like the other tomato plants they may have – albeit a different colour.
For now, only US consumers can enjoy the fruits of this research, and the patented technology serves to protect the considerable investment in getting the product to market. With recent moves indicating there may be a loosening of the tight EU and UK legislation on genetically modified organisms, it is possible that we might see these engineered superfoods come back to East Anglia in future.
While we wait, however, it is possible to buy purple-tinged tomatoes produced by conventional breeding – although these produce the anthocyanins just in the skin, so you would have to eat an awful lot of tomatoes to get the same amount as in the Empress tomato. Or, of course, buy any of the many other heritage varieties or other purple plant products available here.