DHA, an essential fatty acid for brain development and protection, could be directly obtained in the diet from marine sources (fish or algae). It could also be synthesized from dietary precursors such as the omega-3 - α-linolenic acid (ALA) - however the conversion efficiency is low.
DHA is essential for brain function and its deficiency is implicated in many types of neurological disorders, including anxiety.
A study published in Biochim Biophys Acta by the University of Los Angeles in 2015, demonstrates that Curcumin enhances the synthesis of DHA from its precursor (ALA) in rodents, and elevates levels of enzymes (FADS2, Elov2) involved in the synthesis of DHA.
In vivo treatment with both curcumin and ALA reduced anxiety-like behavior in rodents which could be explained by the increase of DHA levels in the brain.
These results are particularly interesting for populations following a vegan or plant-based diet who do not consume omega-3 rich foods from marine sources (fish, krill) containing DHA.
Today, non-animal DHA supplementation is possible with algae oil food supplements.
Source: Wu A, Noble EE, Tyagi E, Ying Z, Zhuang Y, Gomez-Pinilla F. Curcumin boosts DHA in the brain: Implications for the prevention of anxiety disorders. Biochim Biophys Acta. 2015 May;1852(5):951-61.