Jack Mackerel are rich in omega-3 fatty acids, as well as high levels of vitamin B12 (nearly 70% of your daily requirement). They contain minerals like selenium, copper, phosphorus, magnesium, and iron. There are also smaller amounts of vitamin A, potassium, zinc and sodium. Along with 230 calories per filet – an average of 100 grams – there are also 21 grams of protein, representing roughly 40% of your daily required intake. Due to this impressive nutrient profile and the different ways to prepare jack mackerel, it remains one of the most popular and readily consumed fish in the world.