Designer plants have vital fish oils in their seeds

MOVE over, cod liver oil. A biofuel crop related to cabbages, called camelina, has been genetically modified to produce components of fish oils beneficial for cardiovascular health. The approach could relieve some of the pressure on the oceans.

The flesh of oily fish such as mackerel and salmon, plus the livers of white fish such as cod, are good sources of omega-3 fatty acids. The most important ones are eicosapentaenoic acid (EPA) – known to reduce the risk of heart disease – and docosahexaenoic acid (DHA) – a lack of which has been linked to visual and cognitive problems.

Breast milk is a good source of both, and our bodies can make small amounts of EPA from another omega-3 called alpha-linolenic acid (ALA) found in nuts and vegetable oil, which is then converted into DHA.

The richest source of these fatty acids is fish. However, they do not produce the acids themselves. In the wild, they get them from eating smaller fish that have eaten algae, the only organisms that can make appreciable amounts of EPA and DHA. Farmed fish are fed fishmeal enriched with fish oil containing these fatty acids.

Every year, around a million tonnes of oil is extracted from ground-up fish. A tenth of this goes to make fish-oil capsules and the rest is given to farmed fish. But supplies are limited and unsustainable, says Douglas Tocher of the Institute of Aquaculture at the University of Stirling, UK.

Now Johnathan Napier and colleagues at Rothamsted Research in Harpenden, UK, have created an alternative, sustainable source of EPA and DHA. They took seven genes that algae use to produce these fatty acids and inserted them into the genome of Camelina sativa, a plant chosen because its seeds are already rich in ALA. The seeds of the modified plant yielded oil that, when purified, contained around 12 per cent EPA and 14 per cent DHA – the same proportions as in fish oil.