Mackerel is a saltwater fish that, along with tuna and salmon, is popularly known for being a good source of Omega-3. Omega-3 is a type of polyunsaturated fatty acid (PUFA) and there are 3 types: eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and alpha-linolenic acid (ALA). EPA and DHA are derived from marine sources, while ALA is sourced from plants.
Fatty fish, like mackerel, are high in EPA and DHA: 3 ounces of mackerel (flesh) can provide up to ~ 1.6g of EPA and DHA. To date, the American Heart Association recommends at least 2 servings of fish every week, especially those rich in Omega-3s. Eating Omega-3 rich foods can help to bring the Omega-3 : Omega-6 ratio closer to 1:1, which is recommended by studies as being the best balance.
Omega-3s have anti-inflammatory, anti-arrhythmic and anti-thrombotic effects and are protective to the heart and cardiovascular system. Several studies including the Diet And Reinfarction Trial (DART) and the GISSI-Prevention Trial, suggest that high Omega-3 intake can prevent a second coronary event in susceptible patients.
Health note: Varieties of mackerel have in different levels of mercury. For example, King and Spanish mackerel have high mercury levels while Atka and Atlantic mackerel contain lower levels. Persons should limit eating the high mercury-containing varieties; pregnant women and younger children should avoid it altogether. Also, mackerel over-fishing is a growing concern, so be sure to buy from sources that promote sustainable mackerel.