Researchers have revealed that genetically modified Camelina plants produce omega-3 fish oils suitable for feeding Atlantic salmon. The new GMO plants can produce up to 20% of eicosapentaenoic acid (EPA), one of the two omega-3 LC PUFA conferring health benefits. 

Consumption of omega-3 fish oils, specifically long-chain polyunsaturated fatty acids (omega-3 LC-PUFA), through eating oily fish like salmon and mackerel, has been linked with improved cardiovascular health and cognitive development. The primary dietary sources of these fatty acids are wild or farmed fish.

Fish accumulate the omega-3 fish oils through eating other organisms in the marine food chain or, in farmed fish, through fishmeal and fish oil in feeds. Currently there is a gap between supply and demand for these fish oils and new sources are required for the aquaculture industry and for direct human consumption.

Credit: Dr. Eric Leclerq, University of Stirling

Professor Christine Williams of University of Reading, an expert on the impact of dietary fats in human health who was not involved in the new work, said, "Long chain omega 3 fats are essential components of the developing brain and play a vital role in maintaining heart health. However they are made in the body in only very small amounts and need to be supplied in the diet. 

"Although fish are the richest dietary source of these fats there have been concerns about their low levels in farmed fish. In recent years fish farming has needed to use a mixture of fish oils and vegetable oils in the feeds of the fish due to the lack of availability and increasing costs of fish oils. This study showed this novel GM source of long chain omega-3 fats was able to replace fish oils. This will allow farmed fish – the major source of fish in the UK diet – to retain the levels of essential long chain omega-3 fats needed for human health."

Extracted oils from the plants grown in the glass house were used as a replacement for marine fish oil in feeds for Atlantic salmon. Growth performance, feed efficiency, fish health and nutritional quality for the human consumer were unaffected when dietary fish oil was substituted with oil from the GM plants. The study is published today in the journal Scientific Reports.

Rothamsted Research scientists have being carrying out research into metabolically engineering plants to produce omega-3 fish oils for more than 15 years. In the current study they used five microalgal and fungal genes to engineer Camelina plants (Camelina sativa) in order to generate a renewable terrestrial source of omega-3 fish oils.

Dr. Monica Betancor, who carried out the experiments at the University of Stirling, said,"With this work we had the opportunity to test the potential of this novel source of EPA to substitute for fish oil in fish feeds. We used three diets, one containing the standard fish oil used routinely in the fish feed industry, one containing oil from Camelina plants that have not been genetically engineered and one that contained oil derived from plants that have been engineered to produce 20% EPA in their seeds. Each diet was tested with three separate groups of Atlantic salmon for seven weeks.

"At the end of the experiment we examined fish from the different treatments and found that the oil derived from the GM plants can effectively substitute for fish oil in salmon feeds. This is highly significant because fish oil is a finite and limited resource, very expensive and the increasing demands for it by the fish farming industry will not be met in the future. So we really need to develop effective alternatives like this one."

Professor Douglas Tocher, leading the salmon feeding study at the University of Stirling, added, "There is a fundamental lack of omega-3 LC-PUFA to satisfy the recommended dietary requirements for humans, and fish are our main dietary source. The development of these novel plant oils, tailored to human requirements, represent a sustainable way to farm fish with high levels of omega-3 fish oils that maintain their high nutritional value to the human consumer while preserving wild fish stocks." 

Citation: Betancor, M.B. et al., 'A nutritionally-enhanced oil from transgenic Camelina sativa effectively replaces fish oil as a source of eicosapentaenoic acid for fish', Sci.Rep. 5, 8104; DOI: 10.1038/srep08104 (2015)