Oily fish is the richest source of Omega 3. This includes salmon, mackerel, rainbow trout, fresh tuna, herring, shrimp, crab, sardines and pilchards. Tinned fish is as acceptable as fresh. Weaker sources include flaxseed or linseed oil, rapeseed or canola oil, walnuts, and dark green vegetables.
What about tinned tuna? Omega 3 fat is greatly reduced during the tinning process. Therefore tinned tuna should not be counted as one of your weekly portions of oily fish. If fresh fish is too expensive or is not available in your area, choose tinned salmon, mackerel or sardines.