Farmed Salmon and Farmed Rainbow Trout-Excellent Sources of Vitamin D?

Fatty fish are generally stated as having high vitamin D content and among these are salmon and trout. In the aquaculture industry of salmonids the two main species produced are Salmo salar (Atlantic salmon) and Onchorhynchus mykiss (rainbow trout). Published data have shown lower content of vitamin D in farmed than in wild species, but generally data on vitamin D in farmed salmon and rainbow trout are scarce. In commercial production facilities we aimed to study the variation of vitamin D in farmed salmon and rainbow trout prepared for sale to consumer. Thirteen organically produced salmon and 18 rainbow trout were sampled within the range 0.7-4.0 kg of gutted weight. All fish were ready for consumption, and analysed for content of vitamin D3, 25-hydroxyvitamin D3, and fat. Mean vitamin D3 content in salmon and rainbow trout was 1.6 ± 0.5, and 5.0 ± 2.3 I¼g/100 g, respectively. Compared to vitamin D3, the content of 25-hydroxyvitamin D3 was 11% and 3%, respectively. In farmed salmon a linear relationship with vitamin D3 being dependent on weight (P<0.05) as well as to fat content (P<0.05), while no similar relationship was found for farmed rainbow trout. Despite this, both species exhibit a linear correlation between fat and gutted weight (P<0.001). The results indicate that there is a difference in the storage of vitamin D between the two salmonids, as 25- found in the salmonids is challenging farmed salmon and farmed trout as an essential vitamin D source.