DHA is a form of omega-3 that is absolutely crucial to proper brain development. Since it’s difficult to digest, absorb and synthesize from whole foods, supplements may be important, and necessary, for children. (http://ajcn.nutrition.org/content/57/5/703S.1.short) Luckily, there are some wonderful forms of plant-based DHA, sourced from algaes.
Since there’s no risk associated with supplementing DHA, particularly when taking plant-based DHA that has drastically less potential for mercury or other toxin contamination than fish, it can also be taken throughout adulthood to ensure healthy brain, nerve and heart function. (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3681100/)