The animal research behind the purple tomato

UK newspaper The Times recently reported renewed efforts to introduce a genetically modified purple tomato into British supermarkets, following prior testing in mice. 

The purple tomato was developed by researchers at the John Innes Centre by introducing two genes, through gene editing. They introduced genes from the snapdragon (Antirrhinum) into tomatoes, enabling the accumulation of antioxidants called anthocyanins. These compounds are also found in blueberries and blackberries and are associated with anti-inflammatory properties and may affect disease-related processes. 

This technology enabled targeted modification of the tomato genome, which reduces the potential for toxicity or allergenic responses, as anthocyanins have long been considered safe. However, determining whether these high anthocyanin levels had biological relevance required animal research.  

Despite the clear scientific rationale for the purple tomato, GM foods remain controversial. Some long-standing critics still describe genetic modification as “Frankenstein technology”, raising concerns about tampering with nature. 

In a study published in Nature Biotechnology in 2008, the same scientists tested the purple tomatoes in cancer-prone mice to assess their effects in a whole organism. Mice fed a diet containing the purple tomatoes lived approximately 30% longer than mice fed standard tomatoes, with survival increasing from around 142 days to 182 days. 

These experiments with mice provided early biological evidence that the modified tomatoes could affect disease-related processes, which could never have been tested as effectively using available methods at the time in any other way.