There are two groups of essential omega-3 fatty acids.For more information on these groups go to Omega-3 Fatty Acids.
One essential omega-3 fatty acid, ALA (alpha-linolenic acid), is plant-based and can be found in significant amounts in flaxseed, flaxseed oil, walnuts, walnut oil, chia seeds, tofu, soybean oil, canola oil, and other seed oils. It is also found in some vegetables such as spinach in lesser amounts. A healthy diet that includes plenty of leafy greens and a small amount of the healthy fats listed should supply enough ALA.
However, advertising comparing the high quantities of omega-3 fatty acids in the form of ALA in these nut and seed oils to the omega-3 fatty acids in fish should be taken with a grain of salt. While ALA is important, it is a different omega-3 fatty acid than those found in fish: DHA and EPA. All three are necessary, and although the body is capable of changing a small amount of ingested ALA to DHA and EPA it does not appear to be able to synthesize anywhere near as much of the latter two as we need.
Fish and shellfish are the best source of the omega-3 fatty acids DHA and EPA. The more oily fish from cold norther waters pack the biggest punch in terms of DHA and EPA. The following lists are in approximate descending order of omega-3 content with herring and mackerel supplying the most with almost 2 grams per serving.
Fish which supply 1 gram or more of combined DHA and EPA omega-3 fatty acids per 3.5 oz serving (the daily amount recommended by the American Heart Association)
- Pacific and jack mackerel
- Tuna, bluefin, fresh
- Spanish mackerel
- Coho salmon
- Atlantic mackerel
- Trout, mixed species
- Rainbow trout
- Sardine, canned in oil (drained)
- Striped bass
Fish and shellfish which supply 0.5 – 1 gram of combined DHA and EPA omega-3 fatty acids per 3.5 oz. serving
- Tuna, white, canned in water
- Sockeye salmon
- Shrimp, canned
Fish and shellfish which supply 0.2 and 0.5 gram of combined DHA and EPA omega-3 fatty acids per 3.5 oz. serving
- Alaskan King Crab
- Dungeness crab
- Flounder and Sole
- Tuna, light, canned in water
- Catfish, wild
- Shrimp, mixed species
- Scallop, bay and sea
- Blue crab
Data was drawn from the USDA National Nutrient Database. If you would like to know about the omega-3 content of another fish popular in your area, feel free to post the request below and I will try to research it.
For more information on fatty acids in general and omega-3 fatty acids specifically please see:
Also related: Week Ten – Eat More Fish!