Fish can be contaminated with heavy metals (mercury, cadmium, arsenic, lead), pesticides, dioxins, furans and PCBs. These toxic substances are mainly taken in via the skin and the gills of the fish. It is therefore advisable to always remove the skin of the fish in order to limit the intake of harmful substances. Small fish species (anchovies, sardines, mackerel) contain less toxic substances than large fish species.
Some large fish species (shark, marlein, swordfish, king mackerel, tilefish) contain a lot of mercury and are therefore not recommended during pregnancy or breastfeeding. Tuna (fresh of from a can), wild salmon from the Baltic Sea and herring from the Baltic Sea can also only be eaten in a limited way (1 portion per week) because of the degree of contamination. A well controlled fish oil supplement offers a safe alternative in these cases.
For those that do not like fish or do not want to eat fish, sea algae form an alternative. Oil from algae is the only vegetable source of EPA and DHA. Omega-3 fatty acids from algae are available as supplements.