OBJECTIVE: While the cardiovascular, anti-inflammatory and mood benefits of omega-3 supplementation containing long chain fatty acids (LCPUFAs) such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are manifest, there is no scientific consensus regarding their effects on neurocognitive functioning. This review aimed to examine the current literature on LCPUFAs by assessing their effects on cognition, neural functioning and metabolic activity. In order to view these findings together, the principle of neural efficiency as established by Richard Haier ("smart brains work less hard") was extended to apply to the neurocognitive effects of omega-3 supplementation. METHODS: We reviewed multiple databases from 2000 up till 2013 using a systematic approach and focused our search to papers employing both neurophysiological techniques and cognitive measures. RESULTS: Eight studies satisfied the criteria for consideration. We established that studies using brain imaging techniques show consistent changes in neurochemical substances, brain electrical activity, cerebral metabolic activity and brain oxygenation following omega-3 supplementation. CONCLUSIONS: We conclude that, where comparison is available, an increase in EPA intake is more advantageous than DHA in reducing "brain effort" relative to cognitive performance.