Don’t we need DHA to be healthy? You cannot consume ALA and rely on it to give you DHA because conversion of ALA to DHA is poor. The science is there. We only convert about 4% of ALA to DHA, and for EPA plus DHA, only 12%. See the study below:
Vegans can easily get DHA by taking microalgae-based DHA supplements. I recommend taking DHA and EPA supplements from Deva Nutrition. The Deva supplements contain about 130 mg of DHA per pill, and it is recommended you take one or two per day. Let’s just round it up and say we need 200 mg of DHA per day (there is actually no medical consensus on how much DHA you need per day).
Suppose you didn’t want to take DHA supplements because you couldn’t afford them. If conversion of ALA to DHA is 4% then that means we need 5 grams of ALA per day. 15% of chia seeds by weight is ALA, which means we only need 33 grams of chia seeds per day, which is about two tablespoons.