Supplementation with oil rich in eicosapentaenoic acid, but not in docosahexaenoic acid, improves global cognitive function in healthy, young adults: results from randomized controlled trials.

BACKGROUND: Evidence regarding the effects of the omega-3 (É·-3) PUFAs (n-3 PUFAs) DHA and EPA on cognition is lacking. OBJECTIVES: We investigated whether supplementation with oils rich in EPA or DHA improves cognition, prefrontal cortex (PFC) hemoglobin (Hb) oxygenation, and memory consolidation. METHODS: Healthy adults (n = 310; age range: 25-49 y) completed a 26-wk randomized controlled trial in which they consumed either 900 mg DHA/d and 270 mg EPA/d (DHA-rich oil), 360 mg DHA/d and 900 mg EPA/d (EPA-rich oil), or 3000 mg/d refined olive oil (placebo). Cognitive performance and memory consolidation were assessed via computerized cognitive test battery. PFC Hb oxygenation was measured using near infrared spectroscopy (NIRS). RESULTS: Both global accuracy and speed improved with EPA-rich oil compared with placebo and DHA-rich oil [EPA vs. placebo accuracy: estimated marginal mean (EMM) = 0.17 (95% CI: 0.09, 0.24) vs. EMM = 0.03 (95% CI = -0.04, 0.11); P = 0.044; EPA vs. placebo speed: EMM = -0.15 (95% CI: -0.22, -0.07) vs. EMM = 0.03 (95% CI: -0.05, 0.10); P = 0.003]. Accuracy of memory was improved with EPA compared with DHA [EMM = 0.66 (95% CI: 0.26, 1.06) vs. EMM = -0.08 (95% CI: -0.49, 0.33); P = 0.034]. Both EPA- and DHA-rich oils showed trends towards reduced PFC oxygenated Hb (oxy-Hb) compared with placebo [placebo: EMM = 27.36 µM (95% CI: 25.73, 28.98); DHA: EMM = 24.62 µM (95% CI: 22.75, 26.48); P = 0.060; EPA: EMM = 24.97 µM (95% CI: 23.35, 26.59); P = 0.082]. CONCLUSIONS: EPA supplementation improved global cognitive function and was superior to the oil enriched with DHA. Interpreted within a neural efficiency framework, reduced PFC oxygenated Hb suggests that n-3 PUFAs may be associated with increased efficiency.These trials were registered in the clinical trials registry (https://clinicaltrials.gov/) as NCT03158545, NCT03592251, NCT02763514.

Differential Effects of DHA- and EPA-Rich Oils on Sleep in Healthy Young Adults: A Randomized Controlled Trial.

Emerging evidence suggests that adequate intake of omega-3 polyunsaturated fatty acids (n-3 PUFAs), which include docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), might be associated with better sleep quality. N-3 PUFAs, which must be acquired from dietary sources, are typically consumed at suboptimal levels in Western diets. Therefore, the current placebo-controlled, double-blind, randomized trial, investigated the effects of an oil rich in either DHA or EPA on sleep quality in healthy adults who habitually consumed low amounts of oily fish. Eighty-four participants aged 25-49 years completed the 26-week intervention trial. Compared to placebo, improvements in actigraphy sleep efficiency (p = 0.030) and latency (p = 0.026) were observed following the DHA-rich oil. However, these participants also reported feeling less energetic compared to the placebo (p = 0.041), and less rested (p = 0.017), and there was a trend towards feeling less ready to perform (p = 0.075) than those given EPA-rich oil. A trend towards improved sleep efficiency was identified in the EPA-rich group compared to placebo (p = 0.087), along with a significant decrease in both total time in bed (p = 0.032) and total sleep time (p = 0.019) compared to the DHA-rich oil. No significant effects of either treatment were identified for urinary excretion of the major melatonin metabolite 6-sulfatoxymelatonin. This study was the first to demonstrate some positive effects of dietary supplementation with n-3 PUFAs in healthy adult normal sleepers, and provides novel evidence showing the differential effects of n-3 PUFA supplements rich in either DHA or EPA. Further investigation into the mechanisms underpinning these observations including the effects of n-3 PUFAs on sleep architecture are required.