There are two essential fatty acid groups; linoleic acid (omega-6) and alpha-linolenic acid (omega-3). The essential alpha-linolenic acid (from plant sources) can be restructured in the body to produce the longer chained EPA and DHA fatty acids, EPA and DHA can also be obtained directly from algae and from animal sources, primarily fish.
Ground flax seeds, hemp seeds, chia seeds, walnuts and leafy greens are the best sources of alpha-linolenic acid and currently, algae derived omega-3 supplements appear to provide the safest source of EPA and DHA (if not rancid). Read more . . .