Without supplementing with a plant source DHA supplement, it’s a little difficult to get the amount of DHA that has associated health benefits. Additionally because you also need the EPA to get the potential positive outcomes you would need to mix up the diet significantly. It may be a good idea and certainly more practical to take a plant-based omega-3 supplement containing both DHA and EPA. Although most omega-3 supplements are made from fish sources, vegetarian supplements are available and are derived mainly from plant sources, such as flaxseed. There are other vegetarian sources such as algae/seaweed that contain DHA but not EPA. Plant foods (e.g. nuts, oils, vegetables, etc.) contain both omega-3 and omega-6 fatty acids. However the plant-derived omega-3 fatty is acid alpha-linolenic acid (ALA), which can be converted to EPA & DHA but very inefficiently (8-20% of ALA to EPA; .5-9% to DHA) and therefore is not considered a good source of the two potentially beneficial compounds. The other problem with plants as the only source is that that they contain high amounts of omega-6 fatty acids (FA) which competes with the benefits of omega-3s, meaning omega-6 FA tend to increase harmful inflammation, while omega-3s tends to lower it. Of course plant foods have their own special health benefits. At the end of the da,y if you are a vegan looking for the specific benefits, such as maintaining heart, brain, hearing and vision health, attributed to omega-3s, look for vegetarian capsules that can supply ~600mgs of omega -3s made up of 360mgs EPA & 240mgs DHA. Take 1 capsule daily unless a qualified physician advises more for a specific condition.