Which fats are rich in unsaturated fatty acids?

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Polyunsaturated fatty acids can be divided into the omega-6 and the omega-3 families, according to the position of the first double bond. Both are nutritionally essential for a healthy body. They are necessary for growth and development and for maintaining health. Some foods, including most vegetable oils and oily fish, contain relatively more unsaturated fats than others.

Rich sources of unsaturated fatty acids are:

Omega-3 polyunsaturated fatty acids - oily fish (salmon, mackerel, herring, trout), walnuts, rapeseed, soybean, flax seed, and their oils.
Omega-6 polyunsaturated fatty acids - sunflower seeds, wheat germ, sesame, walnuts, soybean, corn and their oils. Certain margarines (read the label).

See also

British Nutrition Society
http://www.nutrition.org.uk/home.asp?siteId=43§ionId=421&subSectionId=322&parentSection=299&which=1