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As a result it is a major contributor to vitamin A deficiency, which kills up to 700,000 children annually and causes about 300,000 cases of blindness globally each year.
Prof Dale said: "There is very good evidence that vitamin A deficiency leads to an impaired immune system and can even have an impact on brain development.
"Good science can make a massive difference here by enriching staple crops such as Ugandan bananas with pro-vitamin A and providing poor and subsistence-farming populations with nutritionally rewarding food... We know our science will work."
The new variety contains selected genes which raise the level of beta-carotene in the banana, which is commonly chopped and steamed as a foodstuff across East Africa. The GM banana has orange rather than cream-coloured flesh because of its high content of beta-carotene, which is converted by the body into vitamin A.
The researchers, who are backed by $10m in funding from the Bill and Melinda Gates Foundation, have grown test varieties in Uganda, where about 70 per cent of the population rely on the banana for the bulk of their nutrition.
Some 10kg of the resulting "elite" banana crop is now being sent to the United States for the world's first human test of a GM banana to assess how successful it is in producing higher levels of vitamin A in the body.
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The results should be known by the end of this year and if legislation being studied by Ugandan legislators to licence the commercial sale of GM crops becomes law the first plants could be available to farmers and smallholders within six years.
The scientists said there was no reason why the new banana could not also be grown in other East African countries - Rwanda, Kenya, Tanzania and parts of the Democratic Republic of Congo - where it is also staple, subject to official approval.
They also hold out the possibility that other types of banana, such as the plantain grown widely in West Africa, could also undergo the same modification.
Prof Dale said: "This project has the potential to have a huge positive impact on staple food products across much of Africa and in doing so lift the health and wellbeing of countless millions of people over generations."
The progress of the research will also reignite the debate about the suitability and effectiveness of genetic science in tackling the problems faced by the developing world as populations rise and the pressure to provide sufficiently nutritious staples increases.
Opponents of GM science said today that governments need to be aware that the changing of nutrient levels in basic foodstuffs could have unforeseen consequences.
Dr Helen Wallace, of GeneWatch, said: "There is evidence that too much beta-carotene can be cancerous so what happens when people who are not vitamin A deficient eat this crop? There are more effective solutions to these issues such as targeted supplements and diversification of crops. These trials have no way of establishing whether these changes are beneficial rather than harmful in the long term."
- Independent