Fish oil and mental health: the role of n-3 long-chain polyunsaturated fatty acids in cognitive development and neurological disorders.
Epidemiological and experimental studies have indicated that consumption of more n-3 long-chain polyunsaturated fatty acids may reduce the risk for a variety of diseases, including cardiovascular, neurological and immunological disorders, diabetes and cancer. This article focuses on the role of marine n-3 long-chain polyunsaturated fatty acids in brain functions, including the development of the central nervous system and neurological disorders. An overview of the major animal studies and clinical trials is provided here, focusing on fatty acid supplementation during pregnancy and infancy, and prevention and management of Alzheimer’s disease, schizophrenia, depression and attention deficit hyperactive disorder. Although an optimal balance in n-3/n-6 long-chain polyunsaturated fatty acid ratio is important for proper neurodevelopment and cognitive functions, results from randomized controlled trials are controversial and do not confirm any useful effect of supplementation on development of preterm and term infants. The relationship between fatty acid status and mental disorders is confirmed by reduced levels of n-3 long-chain polyunsaturated fatty acids in erythrocyte membranes of patients with central nervous system disorders. Nevertheless, there are very little data supporting the use of fish oil in those patients. The only way to verify whether n-3 long-chain polyunsaturated fatty acids are a potential therapeutic option in the management and prevention of mental disorders is to conduct a large definitive randomized controlled trials similar to those required for the licensing of any new pharmacological treatment.
Int Clin Psychopharmacol. 2006 Nov;21(6):319-36
Associations between cod liver oil use and symptoms of depression: the Hordaland Health Study.
BACKGROUND: Clinical trials suggest that omega-3 fatty acids improve the outcome of depression. This study aimed to evaluate the association between intake of cod liver oil, rich in omega-3 fatty acids, and high levels of symptoms of depression and anxiety in the general population. METHODS: We used data from the “The Hordaland Health Study ‘97-’99” (HUSK), a population based cross-sectional health survey from Norway including 21,835 subjects aged 40-49 and 70-74 years. Symptoms of depression and anxiety were measured by The Hospital Anxiety and Depression Scale (HADS). We used logistic regression to study associations. RESULTS: Among the participants, 8.9% used cod liver oil daily. A total of 3.6% had high levels of depressive symptoms. The prevalence of such depressive symptoms among the subjects who used cod liver oil daily was 2.5%, as compared to 3.8% in the rest of the population. The users of cod liver oil were significantly less likely to have depressive symptoms than non-users after adjusting for multiple possible confounding factors (odds ratio=0.71, 95% confidence interval 0.52 to 0.97). These factors included age, gender, smoking habits, coffee consumption, alcohol consumption, physical activity, and education. In addition, we found that the prevalence of high levels of depressive symptoms decreased with increasing duration (0-12 months) of cod liver oil use (multivariate adjusted test for trend, P=0.04). We were only able to study this latter association in a subset of the population aged 40-46 years. LIMITATIONS: Data are cross sectional. CONCLUSIONS: The findings indicate that regular use of cod liver oil is negatively associated with high levels of depressive symptoms in the general population.
J Affect Disord. 2007 Aug;101(1-3):245-9
Omega-3 fatty acid supplementation in patients with recurrent self-harm. Single-centre double-blind randomised controlled trial.
BACKGROUND: Trials have demonstrated benefits of long-chain omega-3 essential fatty acid (n-3 EFA) supplementation in a variety of psychiatric disorders. AIMS: To assess the efficacy of n-3 EFAs in improving psychological well-being in patients with recurrent self-harm. METHOD: Patients (n=49) presenting after an act of repeated self-harm were randomised to receive 1.2 g eicosapentaenoic acid plus 0.9 g decosahexaenoic acid (n=22) or placebo (n=27) for 12 weeks in addition to standard psychiatric care. Six psychological domains were measured at baseline and end point. RESULTS: At 12 weeks, the n-3 EFA group had significantly greater improvements in scores for depression, suicidality and daily stresses. Scores for impulsivity, aggression and hostility did not differ. CONCLUSIONS: Supplementation achieved substantial reductions in surrogate markers of suicidal behaviour and improvements in well-being. Larger studies are warranted to determine if insufficient dietary intake of n-3 EFAs is a reversible risk factor for self-harm.
Br J Psychiatry. 2007 Feb;190:118-22
Relationship between omega-3 fatty acids and plasma neuroactive steroids in alcoholism, depression and controls.
Deficiency in the long-chain omega-3 fatty acid, docosahexaenoic acid (DHA) has been associated with increased corticotropin releasing hormone and may contribute to hypothalamic pituitary axis (HPA) hyperactivity. Elevated levels of the neuroactive steroids, allopregnanolone (3alpha,5alpha-THP) and 3alpha,5alpha-tetrahydrodeoxycorticosterone (THDOC) appear to counter-regulate HPA hyperactivity. Plasma essential fatty acids and neurosteroids were assessed among 18 male healthy controls and among 34 male psychiatric patients with DSM-III alcoholism, depression, or both. Among all subjects, lower plasma DHA was correlated with higher plasma THDOC (r = -0.3, P < 0.05) and dihydroprogesterone (DHP) (r = -0.52, P < 0.05). Among psychiatric patients lower DHA was correlated with higher DHP (r = -0.60, P < 0.01), and among healthy controls lower plasma DHA was correlated with higher THDOC (r = -0.83, P < 0.01) and higher isopregnanolone (3beta,5alpha-THP) (r = -0.55, P < 0.05). In this pilot observational study, lower long-chain omega-3 essential fatty acid status was associated with higher neuroactive steroid concentrations, possibly indicating increased feedback inhibition of the HPA axis.
Prostaglandins Leukot Essent Fatty Acids. 2006 Oct-Nov;75(4-5):309-14
Omega-3 fatty acid deficiency in major depressive disorder is caused by the interaction between diet and a genetically determined abnormality in phospholipid metabolism.
Omega-3 fatty acids are a type of polyunsaturated fatty acid (PUFA). A growing body of evidence suggests that this form PUFA is a useful and well tolerated treatment for major depressive disorder, a common and serious mental illness. The efficacy of omega-3 PUFA is routinely explained as being due to a deficiency caused by inadequate dietary intake of this class of fatty acid. The hypothesis considered states that low omega-3 PUFA abundance in patients with major depressive and related disorders is due to an underlying genetically determined abnormality. The hypothesis can explain why although a specific and consistent deficit in omega-3, but not omega-6, PUFA occurs in major depressive and related disorders, the literature does not consistently support the notion that this is due to deficient dietary intake. Specifically it is hypothesized that having genetically determined low activity of fatty acid CoA ligase 4 and/or Type IV phospholipase A(2) combined with the low dietary availability of omega-3 PUFA results in reduced cellular uptake of omega-3 PUFA and constitutes a risk factor for depression. The hypothesis also has important consequences for the pharmacological treatment of depression in that it predicts that administering agents which enhance phospholipid synthesis, particularly those containing ethanolamine such as CDP-ethanolamine, should be effective antidepressants especially when co-administered with omega-3 PUFA.
Med Hypotheses. 2007;68(3):515-24. Epub 2006 Oct 12
Serum omega-3 fatty acids are associated with variation in mood, personality and behavior in hypercholesterolemic community volunteers.
Low dietary intake of omega-3 polyunsaturated fatty acids has been linked to several features of psychiatric symptomatology, including depression, disorders of impulse control, and hostility. Preliminary intervention trials of omega-3 fatty acid supplementation for clinical depression and other disorders have reported benefit. However, few studies have investigated the relationships between these fatty acids and normative variability in mood, behavior and personality. Participants were 105 hypercholesterolemic, but otherwise healthy, non-smoking adults. Fasting serum alpha-linolenic (alpha-LNA), eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) were assayed with gas chromatography. Participants completed the Beck Depression Inventory (BDI), the NEO Five Factor Personality Inventory (NEO-FFI) and the Barratt Impulsiveness Scale (BIS). In multivariate analyses, higher levels of the long chain omega-3 PUFAs, EPA and DHA, were associated with significantly reduced odds of scoring >/=10 on the BDI. Similarly, DHA and EPA covaried inversely with NEO-Neuroticism scores, whereas DHA was positively associated with NEO-Agreeableness. On the BIS, DHA was inversely related to cognitive impulsivity and alpha-LNA was inversely related to motor and total impulsivity. These findings suggest that omega-3 fatty acid status is associated with variability in affect regulation, personality and impulse control.
Psychiatry Res. 2007 Jul 30;152(1):1-10. Epub 2007 Mar 23
Long-chain omega-3 fatty acid intake is associated positively with corticolimbic gray matter volume in healthy adults.
BACKGROUND: In animals, dendritic arborization and levels of brain derived neurotrophic factor are positively associated with intake of the omega-3 fatty acids. Here, we test whether omega-3 fatty acid intake in humans varies with individual differences in gray matter volume, an in vivo, systems-level index of neuronal integrity. METHODS: Fifty-five healthy adults completed two 24h dietary recall interviews. Intake of long-chain omega-3 fatty acids was categorized by tertiles. Regional gray matter volumes in a putative emotional brain circuitry comprised of the anterior cingulate cortex (ACC), amygdala and hippocampus were calculated using optimized voxel-based morphometry on high-resolution structural magnetic resonance images. RESULTS: Region of interest analyses revealed positive associations between reported dietary omega-3 intake and gray matter volume in the subgenual ACC, the right hippocampus and the right amygdala, adjusted for total gray matter volume of brain. Unconstrained whole-brain analyses confirmed that higher intake of omega-3 fatty acids was selectively associated with increased greater gray matter volume in these and not other regions. CONCLUSIONS: Higher reported consumption of the long-chain omega-3 fatty acids is associated with greater gray matter volume in nodes of a corticolimbic circuitry supporting emotional arousal and regulation. Such associations may mediate previously observed effects of omega-3 fatty acids on memory, mood and affect regulation.
Neurosci Lett. 2007 Jun 29;421(3):209-12
Selective deficits in the omega-3 fatty acid docosahexaenoic acid in the postmortem orbitofrontal cortex of patients with major depressive disorder.
BACKGROUND:Epidemiological surveys and peripheral tissue (red blood cells/plasma) fatty acid composition studies suggest that omega-3 fatty acid deficiency is associated with major depressive disorder (MDD) and suicide. It was hypothesized that patients with MDD would exhibit lower frontal cortical concentrations of docosahexaenoic acid (DHA), the principal omega-3 fatty acid in brain, relative to normal controls. METHODS: We determined the total fatty acid composition of postmortem orbitofrontal cortex (Brodmann’s Area 10) from patients with DSM-IV-defined MDD (n = 15) and age-matched normal controls (n = 27) by gas chromatography. RESULTS: After correction for multiple comparisons, the omega-3 fatty acid DHA was the only fatty acid that was significantly different (-22%) in the postmortem orbitofrontal cortex of MDD patients relative to normal controls. Deficits in DHA concentrations were greater in female MDD patients (-32%) than in male MDD patients (-16%), and could not be wholly attributed to lifestyle factors or postmortem tissue variables. CONCLUSIONS: These results demonstrate a selective deficit in the omega-3 fatty acid DHA in the orbitofrontal cortex of patients with MDD. This finding adds to a growing body of evidence implicating omega-3 fatty acid deficiency as well as the orbitofrontal cortex in the pathophysiology and potentially pathogenesis of MDD.
Biol Psychiatry. 2007 Jul 1;62(1):17-24
Fish consumption, n-3 fatty acids, and subsequent 5-y cognitive decline in elderly men: the Zutphen Elderly Study.
BACKGROUND: Indications have been seen of a protective effect of fish consumption and the intake of n-3 fatty acids on cognitive decline. However, studies are scarce and results inconsistent. OBJECTIVE: The objective of the study was to examine the associations between fish consumption, the intake of the n-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from fish and other foods, and subsequent 5-y cognitive decline. DESIGN: Data on fish consumption of 210 participants in the Zutphen Elderly Study, who were aged 70-89 y in 1990, and data on cognitive functioning collected in 1990 and 1995 were used in the study. The intake of EPA and DHA (EPA+DHA) was calculated for each participant. Multivariate linear regression analysis with multiple adjustments was used to assess associations. RESULTS: Fish consumers had significantly (P = 0.01) less 5-y subsequent cognitive decline than did nonconsumers. A linear trend was observed for the relation between the intake of EPA+DHA and cognitive decline (P = 0.01). An average difference of approximately 380 mg/d in EPA+DHA intake was associated with a 1.1-point difference in cognitive decline (P = 0.01). CONCLUSIONS: A moderate intake of EPA+DHA may postpone cognitive decline in elderly men. Results from other studies are needed before definite conclusions about this association can be drawn.
Am J Clin Nutr. 2007 Apr;85(4):1142-7
Maternal seafood consumption in pregnancy and neurodevelopmental outcomes in childhood (ALSPAC study): an observational cohort study.
BACKGROUND: Seafood is the predominant source of omega-3 fatty acids, which are essential for optimum neural development. However, in the USA, women are advised to limit their seafood intake during pregnancy to 340 g per week. We used the Avon Longitudinal Study of Parents and Children (ALSPAC) to assess the possible benefits and hazards to a child’s development of different levels of maternal seafood intake during pregnancy. METHODS: 11,875 pregnant women completed a food frequency questionnaire assessing seafood consumption at 32 weeks’ gestation. Multivariable logistic regression models including 28 potential confounders assessing social disadvantage, perinatal, and dietary items were used to compare developmental, behavioural, and cognitive outcomes of the children from age 6 months to 8 years in women consuming none, some (1-340 g per week), and >340 g per week. FINDINGS: After adjustment, maternal seafood intake during pregnancy of less than 340 g per week was associated with increased risk of their children being in the lowest quartile for verbal intelligence quotient (IQ) (no seafood consumption, odds ratio [OR] 1.48, 95% CI 1.16-1.90; some, 1.09, 0.92-1.29; overall trend, p=0.004), compared with mothers who consumed more than 340 g per week. Low maternal seafood intake was also associated with increased risk of suboptimum outcomes for prosocial behaviour, fine motor, communication, and social development scores. For each outcome measure, the lower the intake of seafood during pregnancy, the higher the risk of suboptimum developmental outcome. INTERPRETATION: Maternal seafood consumption of less than 340 g per week in pregnancy did not protect children from adverse outcomes; rather, we recorded beneficial effects on child development with maternal seafood intakes of more than 340 g per week, suggesting that advice to limit seafood consumption could actually be detrimental. These results show that risks from the loss of nutrients were greater than the risks of harm from exposure to trace contaminants in 340 g seafood eaten weekly.
Lancet. 2007 Feb 17;369(9561):578-85