[1][2] The consumption of DHA (e.g., from fatty fish such as salmon, herring, mackerel and sardines) contributes to numerous physiological benefits, including cognition.

[15] DHA modulates the carrier-mediated transport of choline, glycine, and taurine, the function of delayed rectifier potassium channels, and the response of rhodopsin contained in the synaptic vesicles.

[19][20] Aerobic eukaryotes, specifically microalgae, mosses, fungi, and some animals, perform biosynthesis of DHA as a series of desaturation and elongation reactions, catalyzed by the sequential action of desaturase and elongase enzymes.

This pathway, originally identified in Thraustochytrium, applies to these groups:[21] In humans, DHA is either obtained from the diet or may be converted in small amounts from eicosapentaenoic acid (EPA, 20:5, ω-3).

[22] A "Sprecher's shunt" hypothesis, proposed in 1991, postulates that EPA is twice elongated to 24:5 ω-3, then desaturated to 24:6 ω-3 (via delta 6 desaturase) in the mitochondria, then shortened to DHA (22:6 ω-3) via beta oxidation in the peroxisome.

[23][24] However, the shunt model does not match clinical data, specifically as patients with beta oxidation defects do not display issues in DHA synthesis.

[26] Though mixed and plagued by methodological inconsistencies, there is now convincing evidence from ecological, RCTs, meta-analyses and animal trials show a benefit for omega−3 dietary intake for cardiovascular health.

[1][13] Of the n−3 FAs, DHA has been argued to be the most beneficial due to its preferential uptake in the myocardium, its strongly anti-inflammatory activity and its metabolism toward neuroprotectins and resolvins, the latter of which directly contribute to cardiac function.

[30] A major structural component of the mammalian central nervous system, DHA is the most abundant omega−3 fatty acid in the brain and retina.

[34] Animal research shows effect of oral intake of deuterium-reinforced DHA (D-DHA) for prevention of macular degeneration.

[39] In the early 1980s, NASA sponsored scientific research on a plant-based food source that could generate oxygen and nutrition on long-duration space flights.

[44] Fish oil is widely sold in capsules containing a mixture of omega−3 fatty acids, including EPA and DHA.