Effect of 1 Year Krill Oil Supplementation on Cognitive Achievement of Dutch Adolescents: A Double-Blind Randomized Controlled Trial

Abstract

Long-chain polyunsaturated fatty acids (LCPUFA) are important for brain development and function, maybe especially during adolescence. Observational studies have demonstrated an association between fish consumption (a source of LCPUFA) and cognition in adolescents, but intervention trials are lacking. The goal of the current study was to investigate the effect of one year of krill oil (a source of LCPUFA) supplementation on the cognitive performance of adolescents with a low Omega-3 Index (O3I ≤ 5%). A double-blind, randomized, and placebo-controlled supplementation trial with repeated measurements (baseline (T0), three months (T1), six months (T2), and 12 months (T3)) in adolescents (267 randomized) was executed. Participants were randomized to 400 mg eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) per day in Cohort I or placebo and 800 mg EPA + DHA per day in Cohort II or placebo. O3I was monitored by a finger prick at all time points. At T0, T2, and T3, participants executed a neurocognitive test battery. Covariate corrected mixed models were run with either condition (krill or placebo) or O3I as predictors. Krill oil supplementation led to a small but significant increase in mean O3I, but few participants increased to the intended O3I range (8–11%). There was no significant effect of supplementation on the neurocognitive tests, nor a relationship between O3I and neurocognitive test scores. The increase in O3I was small in most participants, probably due to non-compliance. Possibly the increase in O3I was too small to demonstrate an effect. More research on the influence of LCPUFAs on cognition in adolescents is needed.

Effect of Omega-3 Long Chain Polyunsaturated Fatty Acids (n-3 LCPUFA) Supplementation on Cognition in Children and Adolescents: A Systematic Literature Review with a Focus on n-3 LCPUFA Blood Values and Dose of DHA and EPA

“…It might not be surprising that the change scores did not differ when we consider that there was a clear overlap in DHA blood values between the placebo group and the active group. A similar problem arose in the study of van der Wurff et al, a similar Omega-3 index post-intervention was measured in the placebo and the active group due to non-adherence to the study protocol, which could explain the result of similar cognitive test results in both groups [ 47 ].…”

“…Of the 33 studies included in this review, 13 studies had no reported blood fatty acid concentrations [ 29 , 31 , 33 , 35 , 36 , 38 , 43 , 44 , 45 , 49 , 52 , 53 , 55 ]. In 20 studies, fatty acid concentrations were reported, and the fatty acid concentrations were analyzed in a variety of bodily tissues and blood fractions (note that in some studies multiple fractions were utilized): plasma fatty acids [ 27 , 32 , 33 , 56 ], phospholipids in erythrocyte membranes [ 28 , 41 ], plasma phosphatidylcholine [ 30 ], erythrocyte phosphatidylcholine [ 30 ], erythrocyte phosphatidylethanolamine [ 30 ], cheek cells [ 37 , 48 ], capillary whole blood [ 40 , 46 , 47 , 50 ], serum phospholipids [ 42 , 57 , 58 ], total fatty acids in erythrocyte membrane [ 39 , 56 , 59 ], glycerol-phospholipids in plasma [ 51 ] and erythrocytes [ 54 ]. Unfortunately, recalculation formulae to the O3I equivalence are only available for a limited number of blood fractions [ 60 ].…”

“…There were two studies with an O3I equivalence >6% after supplementation in the active group, however, there were no significant effects of supplementation on cognitive measures [ 28 , 32 ]. The notion that an increase in O3I equivalence is related to improved cognition, is supported by the fact that six [ 30 , 37 , 39 , 46 , 57 , 59 ] out of the 10 studies [ 30 , 37 , 39 , 46 , 47 , 51 , 56 , 57 , 58 , 59 ] that related blood values to cognitive outcomes showed significant positive associations or correlations between (change in) DHA and/or EPA blood values and cognitive tests used.…”

“…Supplementation could either contain only DHA or DHA in combination with EPA. Of the 15 studies [ 27 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 43 , 44 , 45 , 47 ] in which participants received supplementation of ≥450 mg DHA + EPA per day, 8 (i.e., 53%) showed a positive effect [ 27 , 31 , 33 , 34 , 38 , 43 , 44 , 45 ] (see Figure 3 ; note that Jackson a and b, Kennedy, and McNamara are represented twice as they included two supplementation groups). In contrast, in only two of the eight studies with a lower supplementation dosage (i.e., <450 mg DHA + EPA per day) a significant effect was shown [ 29 , 30 ].…”

Omega-3 Fatty Acids in Pregnancy—The Case for a Target Omega-3 Index

“…Perinatal mortality was not significantly reduced (RR 0.75, 95% CI 0.54 to 1.03). Pre-eclampsia might have been reduced (RR 0.84, 95% CI 0.69 to 1.01), corresponding to epidemiologic data [42][43][44]. An improvement of postnatal depression was not found, nor were parameters of cognition improved in the child.…”