Oysters – An Unsung Source of Omega-3 Fats?


Omega-3 in Oysters

By now, you probably know that salmon and other types of fatty fish often contain high levels of omega-3s, fatty acids that have been linked to a number of health benefits. But did you know that oysters, those shelled sea creatures that live on the ocean floor, also contain substantial amounts of these beneficial fats? In fact, if you exclude fish, few marine sources provide as much omega-3 fatty acids as Pacific oysters. Take lobsters, crayfish, clams, shrimp or sea scallops, for example. While tasty, these marine animals provide only about 100 to 300 milligrams of omega-3 fatty acids per a four-ounce serving. An equal-sized serving of Pacific oysters, by contrast, delivers a whopping 1,550 milligrams of omega-3 fatty acids (eastern oysters contain about 500-550 milligrams). To put this into perspective, consider this: salmon, which is often touted as one of the best natural sources of omega-3 fatty acids, contains between 700 and 2,400 milligrams of omega-3s per four ounces (depending on the type of the salmon).

As is the case with other marine animals, the omega-3 fatty acids in oysters occur in two forms: eicosapentaenoic acid (EPA) and docohexaenoic acid (DHA). These long-chain forms of omega-3 are considered particularly potent because they don't have to be converted into other compounds before the body can make use of them. By contrast, shorter-chain omega-3 fatty acids, such as alpha-linolenic acid (ALA) which is found in some plant-based foods such as walnuts and flaxseed, have to be converted into the longer-chain forms before the body can make use of them.

What's also great about oysters is that unlike some other rich sources of EPA and DHA – such as swordfish, tilefish from the Gulf of Mexico, and some types of tuna – oysters are relatively low in mercury. According to data published by the U.S. Food and Drug Administration in June 2014, Pacific oysters contain only about 2 micrograms of mercury per a four-ounce serving. This amount is comparable to the mercury levels reported for sardines and salmon, both of which are known for their low mercury levels.

As you may already know, mercury is a heavy metal that can harm your heart, brain, lungs, kidneys and immune system if you are exposed to it at high levels. What's more, this toxic heavy metal can harm fetuses, infants and young children even at relatively low levels, which is why pregnant and breastfeeding women, as well as parents of young children, are often advised to avoid seafood that is known to be high in mercury, even if it is a good source of omega-3 fatty acids.


References

Dietary Guidelines for Americans 2010, Appendix 11. U.S. Department of Agriculture (USDA) and the U.S. Department of Health and Human Services.




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