I’ve written about omega-3s before, as recently as a year ago, but there continues to be much confusion about these compounds and lots of misinformation about them on the internet. The confusion focuses largely on the difference between the two types of omega-3s. If you take supplements of DHA (or DHA and EPA), do you still need flaxseed? And if you are eating flaxseed, do you need those DHA supplements?
The short answer is that you definitely need the flaxseed (or some equivalent food) and you may need the DHA supplements.
Flaxseeds and a handful of other plant foods provide an omega-3 fat called alpha-linolenic acid or ALA which is an essential nutrient. This means it is absolutely necessary in your diet. Best sources for vegans are flaxseed and flax oil, chia seeds, hempseed oil, walnuts or walnut oil, canola oil, and full fat soyfoods. You can check the vegan food guide to see how much of these foods to eat. (The information is in the bottom right section of the guide.)
The other omega-3 fats are DHA and EPA, two closely-related fats typically found in fatty fish, and to a lesser extent in some sea vegetables. They are not considered essential nutrients because humans can synthesize these fats from ALA. Whether we can make enough for optimal health is a big question, though. Vegans have lower blood levels of these fats than people who eat fish, but how much this matters remains unclear. The jury is still out on the health benefits of DHA and EPA intake. These fats may protect against heart disease as well as dementia and depression, but the findings are conflicting. The good news is that if you choose to take supplements of DHA and EPA (and I do), there are vegan sources derived from algae.
The important thing to remember, though, is that the two types of omega-3 fats are not interchangeable. Whether or not you’re taking supplements of DHA and EPA, you still need a source of ALA, like flaxseeds. And, even with a good source of ALA in your diet, you may benefit from supplements of DHA and EPA, especially if you’re at risk for heart disease or depression.