New case study: improving salmon health through smarter nutrition

Exploring the role of autophagy in salmon health

As salmon farming moves toward more sustainable feeds, fish oils rich in omega-3 fatty acids are increasingly replaced by plant-based oils like soy. While this reduces reliance on marine resources, it also changes the balance of omega-3 and omega-6 fats in salmon diets. Too much omega-6 can lead to fat build-up in the liver and muscles, causing inflammation and health problems for the fish and reduce the nutritional value of salmon for consumers.

This project explored whether spermidine, a natural compound known to boost cellular recycling (autophagy), could help salmon process fats more efficiently and maintain better health. Valued at almost £300k, the partners were the Roslin Institute, University of Stirling, Mowi Scotland, and the University of Glasgow. The project was funded by the UK Seafood Innovation Fund (SIF) and SAIC.

Researchers studied salmon at different life stages and ran feed trials where post-smolt salmon were given diets high in soy oil, with or without spermidine supplementation. They analysed fat profiles in muscle, liver, and adipose tissue, and examined markers of metabolism and inflammation.

Salmon fed plant-based diets showed a decline in omega-3 levels, including DHA - a fatty acid important for heart health - alongside an increase in omega-6 fats and triglycerides. Spermidine supplementation improved fat metabolism, reducing harmful fat build-up and increasing the recycling of fats into energy.

Muscle tissue showed healthier lipid profiles, with lower triglycerides and better balance of fatty acids, suggesting spermidine helps counteract negative effects of plant-based feeds. The supplement was well accepted by salmon, with no impact on feeding behaviour.

These results provide the first evidence that spermidine could support salmon health and improve the nutritional quality of farmed fish. This approach could reduce disease risk, enhance fish welfare, and deliver a product richer in beneficial omega-3s for consumers.

Future research will focus on scaling up trials and exploring commercial applications, paving the way for more sustainable and nutritious aquaculture.

The full  title of this project is ‘Enhancing lipid metabolism and health in farmed Atlantic salmon’.

Read the case study