When it comes to omega 3, not any oil will do

These days we all know how important it is to have good levels of omega 3 oils in our diet. But it is becoming harder to get it from the main traditional source – fish.

However a Deakin University researcher is working on new ways to increase the omega 3 oil contained in farmed fish by changing the fish from within.

With more and more people eating farmed fish, there are growing concerns about how much good omega 3 oils these fish contain. That is because, while many are fed fish oil directly, growing numbers are being fed vegetable oils which do not contain good omega 3 oils and that decrease the nutritional value of the fish.

"There are not enough fish coming from the ocean to meet growing global demand," said Deakin University fish nutrition scientist Dr Giovanni Turchini.

He said that it has resulted in a rapid expansion of aquaculture – or fish farming – however these fish have special nutritional requirements and need to be fed fish oil in order that they still contain high levels of omega 3.

The problem is that current fish oil, in a vicious circle, is derived from the already over-exploited wild fish stock – a situation that is environmentally and economically unsustainable, likely leading to a collapse of the sector within a few years.

"Fish and seafood are the only readily available and edible source of the good omega 3. The omega 3 contained in vegetable products are different and not responsible for any health benefit."

Dr Turchini said many researchers around the world are looking at alternatives to this fish oil. These include feeding the fish different oils such as vegetable oils and animal fats.

"Studies have shown that the fish still grow okay but omega 3 levels are a problem," Dr Turchini said.

"If we go down this path the fish we produce will contain less omega 3 and from a nutritional point of view they are no longer fish, more like chicken."

Other strategies investigated globally to overcome this problem are the use of innovative omega 3 rich oils, such as oils derived from copepods - small crustaceans - algae or genetically modified crops, or even the direct farming of genetically engineered fish. However, Dr. Turchini said "these strategies are not economically viable and we should be very cautious in implementing genetically modified food, particularly in the aquatic environment, where farmed and wild fish interactions are unavoidable".

Dr Turchini is looking at innovative natural methods of producing fish still rich in omega 3 fatty acids without using fish oil.

"I am looking at the basic biology of fish," he said.

"It is changing the fish from within – triggering their dormant capability of transforming fatty acids available in vegetable oils into the good ones."

One interesting aside that has come out of the research has been the changes in the way fish tastes depending on the oils it has been given. The research shows consumers prefer the taste of fish fed with fish oil or animal fats as they have a lighter flavour, while fish fed vegetable oils can be tainted by a muddy or oxidised aftertaste.