By Richard Black
BBC science correspondent
Scientists have genetically engineered plants to produce health-promoting substances usually found in fish.
Arabidopsis is often used to test out new ideas in plant science
The British researchers say this could lead to a new generation of food crops able to reduce the risk of heart disease and other medical conditions.
With fish stocks declining worldwide, biotech crops could provide a more environmentally sound source of the "medicinal" omega fatty acids.
The work is published in the science journal Nature Biotechnology.
Dr Colin Lazarus, from Bristol University, and colleagues put genes for three fatty acids into a plant called Arabidopsis, a relative of the cabbage.
Two of the genes came from algae and the third from a fungus. As the plants grew, the genes turned themselves on to produce omega-3 and omega-6 fatty acids, which are known to have significant health benefits.
"They all belong to the families known as very long-chain polyunsaturated omega-3 and omega-6 fatty acids," explained co-researcher Dr Baoxiu Qi, who now works out of Bath University.
According to the scientists, these genes could, in principal, be added to many different agricultural plants.
"Any plants with green tissue, they all have the potential to produce these long-chain fatty acids," Dr Qi told BBC News Online.
"If we try to increase the omega-3 fatty acids in a plant, a good source would be linseed; and for the omega-6, I think rapeseed would be quite good, or soya.
"As far as I know, this is the first time that genes have been put into higher plants to produce high amounts of fatty acids."
These fatty acids reduce the risk of heart disease, relieve symptoms of inflammatory conditions such as rheumatoid arthritis, and there is also some evidence that they are effective against diabetes.
For all these reasons, they are a prominent ingredient of many health foods.
They are found most commonly in oily fish - but with fish stocks declining and prices escalating in some parts of the world, there is a growing demand for other sources of fatty acids.
The Bath scientists were partially financed by the German biotech company BASF which says it will be pursuing this research further.
It may well be that biotech crops producing such healthy substances will prove less controversial than current GM products.