Seasonal variation of chub mackerel (Scomber colias) selenium and vitamin B12 content and its potential role in human health

Chub mackerel (Scomber colias), an underutilised fish species, has been identified as an excellent source of selenium and vitamin B12, which may prevent and delay cognitive decline and dementia. Given these nutrients’ contents seasonal variability, a complete monthly sampling, involving a specifically adjusted methodology for the determination of vitamin B12 (LC-MS/MS) and its main vitamers and a sensitive analytical technique (ICP-MS) for Se, was carried out. Regarding total vitamin B12 in the chub mackerel muscle, its content varied from 10.0 ± 1.0 μg/100 g in February to 18.9 ± 1.9 μg/100 g in August. It was also shown that methylcobalamin content ranged from 1.12 ± 0.43 (March) to 6.77 ± 0.80 μg/100 g (August), a sixfold increase. Hydroxocobalamin content varied between 3.49 ± 0.12 (February) and 9.62 ± 0.41 μg/100 g (August). The content of Se also had seasonal variability, ranging from 451 ± 14 μg/kg (December) to 606 ± 11 μg/kg (July). In the worst-case scenario, a weekly 160 g meal of this fish would almost guarantee B12 requirements. Three weekly 160 g meals of S. colias would cover, at least, 56% of the Se requirements. Therefore, as first explored here, it is highly relevant a complete, year-round assessment of the chub mackerel’s nutritional value, in order to elaborate finely tuned dietary recommendations.