"We have found oil extracted from Patterson's curse, also known as Salvation Jane, contains high levels of stearidonic acid that fish such as Atlantic salmon can convert to omega-3 oils," said Matthew Miller from the University of Tasmania.
Stearidonic acid (SDA) is converted from an 18-carbon chain to a 20-carbon chain by elongation and desaturation reactions that result in the production of eicosapentaenoic acid (EPA). Further elongation and desaturation transforms EPA into docosahexaenoic acid (DHA).
Omega-3 fatty acids have been linked to a wide-range of health benefits, including cardiovascular disease (CVD), good development of a baby during pregnancy, joint health, behaviour and mood, and certain cancers.
However, fish do not naturally make the omega-3 oils themselves but obtain them from their marine environment.
"The natural sources of omega-3 oils in the marine environment are microbes and microalgae, and fish accumulate the oils when they feed on these organisms," said Miller.
But by feeding fish an oil produced from the toxic weed Miller and his fellow scientists appear to believe that they can offer an alternative source of the shorter chain fatty acids, particularly for fish farms.
Patterson's curse was introduced to Australia from Europe in the 1880s, and is now said to be the dominant pasture weed in southeastern Australia. The plant contains chemical compounds that make livestock ill, and can even be fatal. Processing the weed for oil to feed to fish therefore would suit everyone, said Miller.
"People are being encouraged to eat more fish, and thereby consume more omega-3, but this is placing enormous pressure on wild fish stocks and fish farmers," he said.
"It has created a problem in terms of finding renewable sources of food that farmed fish can convert to omega-3 oils. That's why we were so excited when we found that Patterson's curse could be one of these."
Indeed, fears about dwindling fish stocks, coupled with the proposed risk of pollutants from oily fish, have pushed some in academia and industry to investigate the extraction of omega-3 from alternative sources. Companies such as Martek Biosciences and Lonza are already offering algae-derived omega-3 DHA as a dietary supplement.
And only recently, this website reported on research by BASF, Du Pont and others into producing a sustainable and pollutant-free source of EPA as well as DHA from crops such as soybeans and Brassica.