By Helen Briggs
Science reporter, BBC News
Plants genetically engineered to make fish oils offer a new approach to improving diet, say UK scientists.
Crops such as oilseed rape have been engineered to produce fish oil
Experiments have proved that crops containing genes from marine organisms are able to produce omega 3 fatty acids normally found in oily fish.
Adding the oil to animal feed would create omega 3-rich meat, milk and eggs.
Researchers from the EU-wide Lipgene project say such food would help tackle public health issues like obesity.
Concerns over dwindling fish stocks and marine pollution has led researchers to seek an alternative source of long chain omega 3 fatty acids; fats that have important health benefits, especially for the heart. The best source is oily fish, such as salmon, mackerel and herring, but most people do not get enough in their diet.
Most people don't eat enough oily fish
Omega 3 fatty acids are made not by the fish themselves but by the marine microbes they consume.
Scientists at Rothamsted Research in Harpenden, Herts, isolated key genes from a species of microscopic single-celled marine algae known as Thalassiosira pseudonana.
They inserted the genes into crops such as linseed and oil seed rape and found that the plants were able to synthesise omega 3 fatty acids in their seed oils.
"We know that this works, we've done proof of concept studies in model plants and also in crop plants and we can see the accumulation of some of the fish oils we're interested in," said research group leader Professor Johnathan Napier.
"We're still at the stage where we'd want to optimise and improve the levels that we see so I think we're probably three or four years away from the point where we have something ready for regulatory approval for some sort of limited field release," he added.
The eventual aim is to feed GM-enhanced oils to animals such as chickens and cattle, to produce omega 3 enriched meat, milk and eggs.
This would provide a sustainable source of fish oil amid concern over dwindling fish stocks.
"The big problem is that fish (and fish oils) is a very seriously diminishing natural resource," said Professor Napier.
"There are big problems with the sustainability of natural fish stocks and there are also concerns about pollution of the marine environment so we're interested in trying to produce a sustainable alternative source with these fish oils."
Professor Ian Givens from the Nutritional Sciences Research Unit at the University of Reading said he believed that consumers would see the benefit of such foods, despite the fact they come from transgenic crops.
There is concern over dwindling fish stocks
"There has been a lot of concern and resistance about the whole GM technology in the food chain," he said.
"Things move on. When people are able to see more clearly what the benefits to them are from these sorts of approaches, rather than the benefits to others, I suspect that mindsets will change but it will take time."
New figures released by Lipgene show that only 30% of the UK population is consuming the recommended 450mg/day intake of omega-3 fatty acids.
Teenagers, especially males, and low income groups eat the least of all, said Professor Givens.
The Food Standards Agency (FSA) recommends that everyone should eat two portions of fish a week, including one portion of oily fish.
But because fish can contain pollutants such as dioxins and PCBs, there are limits to the amount that should be consumed, particularly for women who are pregnant and breast feeding.
An FSA spokesperson said an expert committee reviewed the evidence on the relationship between long chain omega 3 fatty acids and cardiovascular disease in 2004.
"Two portions of fish per week, one white and one oily, provides the amount of long chain omega 3 fatty acids that can help prevent heart disease," said the spokesperson.
"The Agency recommends that it is better to eat fish, especially oily fish, rather than fish oil supplements or fish oil fortified foods because as well as being rich in long chain omega 3 fatty acids, fish also contains essential vitamins and minerals and is a good source of protein."