Coriander as a catalyst for omega-3 in fish?
Scientists will investigate to what extent fish cells transform fatty acids from plants into omega-3. In a new trial, rainbow trout will eat plant diets completely free of marine ingredients.
It’s rapeseed oil grown in Saskatchewan, Canada that is being used in the trial. PhD student Kyla Randall from Canada wants to see if the production of the marine omega-3 fatty acids EPA and DHA in rainbow trout is enhanced by a combination of rapeseed oil and coriander oil. Her target is no less than making feed production independent on fish oil.
Coriander reduces omega-6
Coriander oil is added to the feed as a catalyst for the conversion to longer omega-3 fatty acids. This oil contains petroselinic acid (18:1n-12) which is a fatty acid known to reduce the level of the omega-6 fatty acid ARA in mice. It is probable that it might also stimulate omega-3 production within the fish.
Why plant based feed?
When less fish oil is used in the fish feed, the content of marine omega-3 in the fish fillet will decrease.
– Still, from sustainability reasons, we choose to replace parts of the fish oil with plant oils, because fish oil is a very limited resource. The fact that the fish eat less marine omega-3, we try to compensate in this trial with adding bioactive components present in coriander oil in combination with the plant oil rapeseed. This way, we stimulate the fish to convert the fatty acid linoleic acid to the marine fatty acids EPA and DHA, says Bente Ruyter from Nofima, who is co-supervisor for Kyla Randall.
The trials will be done at Aquaculture Protein Centre (APC) at Ås in cooperation with Nofima.
The feed contains no marine resources. To Randall’s knowledge, trials using this kind of feed is minimal. The feed is therefore well suited to study how efficient the conversion from plant oils to omega-3 is. Marine fatty acids are longer and are essential to the fish.
For two weeks rainbow trout will be fed feed containing a mix of rapeseed oil, antioxidants and coriander oil at inclusion levels of 0.5, 1 and 1.5 %. Randall will then extract liver cells and incubate them with radio labelled fatty acids.
By radio labelling the fatty acids, she can track where the fatty acids are transported in the cells, how it transforms, and how genes involved are up- and down regulated.
High levels of ARA causes inflammation of cells. If the effect of the rather expensive coriander oil on reduction on ARA is significant in fish at low levels then it can easily be added to diets.
Kyla Randall is a PhD student at the University of Saskatchewan in Canada, and is visiting the Norwegian University of Life Sciences for doctorate courses and experiments.
Randall is supervised by Dr. Murray Drew of the University of Saskatchewan and Dr. Margareth Øverland at APC, and co-supervised by Dr. Bente Ruyter at Nofima.