Omega-3 fatty acids are mainly found in fish and other marine oils, such as squid, and some plant oils, including flaxseed. Some of the omega-3 acids are essential oils, ie the body can't make them itself but needs them for health.

There has been a lot of discussion about the health benefits. As always in the area of food and health, a lot of companies have made claims about the benefits of supplements etc that aren't really proven. DHA and EPA, two of the fatty acids, are thought to have some benefits, especially for the heart and some cancers, but products are often sold claiming to contain 'essential fatty acids' that do not in fact contain these particular acids, so labels need to be read carefully.

In general, though, it is agreed that oily fish are good for you, so the best way to be sure is to have some once a week - you could try some of these recipes!