It is a good question. The human beings could not synthesize the omega-3 fatty acids. That is why we have to take them from our food.

Salmon, herring, mackerel, sardines and anchovies are rich in omega-3 fatty acids. Other fatty fish have lesser amounts of omega-3 fatty acids. The important question is whether the fish could synthesize omega-3 fatty acids or not.

The fish could not synthesize the omega-3 fatty acids like human beings. What is the origin of omega-3 fatty acid then? The orign is the food habits of fish. Their diets contain much plankton and algae and the fish gets the omega-3 fatty acids from them.

Fish is very healthy, but some precautions must be taken by us. Too much of fatty fish are not good for our health. It is because they could contain lot of poisonous heavy metals like cadmium, arsenic, mercury etc. and the fat soluble chlorinated chemicals like many pesticides, PCBs and dioxins.

But the benefits of fish intake generally outweigh the potential risks. But persons with problems with environmental poisons must be careful with fish consumption. As you know always the dose makes the poison. Twice in a week, 150 to 200 g fish is good for all.