Purple carrots and black tomatoes may seem like a marketing gimmick, but the real reason behind their development is biofortification, the process of adding extra nutrients to foods. But how are such products developed? And how will consumers react? Patrick McGuigan investigates.


Crimson carrots and black tomatoes may sound like something from a modern art still life. But scientists are developing this kind of unusually coloured produce, using traditional breeding techniques, because certain pigments contain nutrients and anti-oxidants that have been shown to fight various health problems.


And the process of boosting nutrients in fruit and vegetables, known as biofortification, may be beginning to capture the imaginations of supermarkets, which appreciate the marketing benefits of eye-catching, better-for-you produce. Wacky coloured vegetables may appeal in particular to children, who are notoriously reluctant to eat their greens, but might be tempted to eat their reds or purples.


In 2002, for example, Sainsbury’s launched a range of violet carrots, grown by Cambridgeshire-based Isleham Fresh Produce, to great media fanfare. The carrots, developed using conventional breeding and growing techniques, contain purple-red pigments called anthocyanins, and beta-carotene. These are antioxidants, which have been shown to fight some forms of cancer and heart disease. There have also been reports that the supermarket is planning to stock a ‘rainbow’ range including yellow, white and red carrots in the near future.


Sainsbury’s is also trialling a new sweet black tomato in some of its stores called the kumato, which is grown from seeds developed by Syngenta. The kumato has high levels of vitamin C and antioxidants, and similar trials are taking place in supermarkets in Spain, Italy and Germany.


US drives innovation


Much of the research into biofortification comes from the US. Sainsbury’s purple carrots, for example, are a breed known as BetaSweet, developed by Texas A&M University. Among its other projects, the university is also looking at developing plums, peaches and nectarines with higher levels of phenolic and anthocyanin compounds, as well as melons with greater beta-carotene content.


Similar research work is being carried out at The Vegetable Crops Research Unit in Madison, Wisconsin. Part of the Agricultural Research Service, the unit has developed bright orange cucumbers with extra beta-carotene and red and yellow carrots, with each pigment delivering specific health benefits. The yellow carrots, for example, contain xanthophylls, which have been linked with good eye health, while the red carrots contain lycopene, which is believed to guard against heart disease and some cancers.


Plant geneticist Philipp Simon, who runs the project, says that improvements to the nutritional quality and flavour of traditional orange carrots has been taking place in the US over 25 years. “Provitamin A carotenoid content of (orange) US carrots has increased from 90ppm in the 1970s to 160ppm today. Much of the US carrot crop is derived from carrots we have developed,” he says. “But the improvement of other carrot pigments (red and yellow) has not yet reached the public.”


Simon adds that biofortified carrots are not being developed to compete with supplement products, but that he believes there “will eventually be numerous bio-fortified products, mainly processed, but some fresh, like carrots” in the supermarkets.


For this to work Simon accepts that consumers will have to be reassured about the products. He says: “Consumers want to know: Is it safe? Is it GM? And most importantly, does it taste good? If they can be assured of safety, acceptable flavour will be the major determinant.”


Fighting disease in the developing world


Much of the work to improve the nutritional content of fresh produce stems from a desire to address malnutrition in the developing world. New nutrient-rich breeds of staples such as potatoes, rice and wheat would go a long way in the fight against disease in the third world.


A good example of this is a project run by Karel Schubert, a biologist at Washington University in St. Louis, Missouri, to increase the folate content in corn and rice. Folate deficiency is the most common nutrient deficiency in the world and has been linked to diseases and disorders including foetal growth retardation and anaemia, along with increased risk of cancer and cardiovascular disease.


Schubert, who is also vice president of science administration and technology management at St Louis’ Donald Danforth Plant Science Center, is working to identify and manipulate critical genes in the metabolic pathway responsible for folate synthesis in plants.


“In simple terms, we have identified a key rate limiting step in the production of folate in plants. Using modern methods of biotechnology and genetic enhancement, we have modified the plant so that it now produces three to four times as much folate,” says Schubert. “Our initial focus is on rice because two-thirds of the world’s population depends on rice as their primary staple. Supplements are always an easy way to provide vitamins and minerals in the developed world but this is not a satisfactory, cost effective and sustainable approach in developing countries, especially in the rural areas. Biofortification of food crops is a very promising approach to meet the nutritional needs for the rural poor.”


Taking the GM route


The desire to improve nutrition in the developing world has also led some to use genetic modification in an effort to ramp up the nutrient content of crops. In India, researchers led by Asis Datta at the Jawaharlal Nehru University, New Delhi, have genetically modified potatoes by adding the AmA1 gene to increase protein levels. The ‘protato’, as it has been labelled, contains a third more protein than normal, as well as heightened levels of amino acids. Government-backed field trials are currently taking place to assess the safety and viability of the crop, but scientists have expressed their concern that people in India may be put off eating the protato if anti-GM campaigners target the new breed.


The controversy surrounding GM has dogged a similar project to boost vitamin A levels in developing countries with GM rice. Developed by Dr Ingo Potrykus of the Swiss Federal Institute of Technology and Dr Peter Beyer of the University of Freiburg in Germany, Golden Rice has been genetically modified to contain beta-carotene, which the body turns into vitamin A. In developing countries, vitamin A deficiency is a major cause of blindness among children.


Many of the patents for the new strain of rice are owned by agribusiness Syngenta, which helped develop it, but the Swiss company has recently announced that it will now donate all new Golden Rice seeds and lines to a specially set up Humanitarian Board, meaning it no longer has any commercial interest in Golden Rice.


Initial field trials of Golden Rice have just been successfully completed in the US and the next step is to carry out trials in the Far East, where the rice will be of most benefit to people. But Golden Rice has been consistently attacked by anti-GM campaigners, such as Greenpeace, who argue that it is being used to grab positive headlines for GMOs at a time when they are under attack in Europe. Furthermore, campaigners say Golden Rice will only provide about 8% of people’s RDA of vitamin A.


But Syngenta spokesman Andrew Coker says: “Golden Rice was never meant to be the answer, but it could be part of the answer. Rice consumption is outstripping production in many developing countries, so we have to look at ways of meeting these needs. Isn’t there a moral issue here? We’ve got to move on.”


Whether Golden Rice can overcome the stigma of GM remains to be seen. But the furore it has sparked suggests that biofortification through genetic modification is a risky path to take. Sticking to traditional breeding techniques to create wild and wonderful new produce seems to be a more likely option to bear fruit in the future.