Mental health dose-responses of fish consumption

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Original author: Henna Karvonen, Foodfiles Ltd 2006.

Cancer dose-responses of fish consumption describe exposure-response functions of brain function and mental health due to fish consumption.

Table. Evidence on the effects of fish on brain function and mental health. Data for most of the conditions is insufficient for drawing conclusions on efficacy or dose-response effect. This is due to limited number of studies. (% change per g/d fish consumed )

Ecological, descriptive and cross-sectional studies Cohort and case-control studies Exposure data from cohort and case-control studies Interventions Exposure data from interventions Comments
Cognitive function in ageing + + Fish - Fish consumption tends to be inversely associated with cognitive impairment and cognitive decline (Quantifiable data among healthy elderly is limited to results in one Dutch cohort).
Dementia/ Alzheimer ‘s disease ++ ++ Fish and omega-3 fatty acids + Omega-3 fatty acids In epidemiolocal studies consumption of ~3 portions of fish/week has been associated with 47 % decrease in the incidence of dementia. Two clinical trials on-going, results expected 2008. Cochrane review concluded that there is a growing body of evidence from biological, observational and epidemiological studies that suggest a protective effect of omega-3 fatty acids against dementia. However, until data from RCT’s becomes available no good evidence to support the use of omega-3 PUFA for the prevention of dementia.
Psychiatric diseases
Depression/ Bipolar disorder ++ ++ Fish and fish oil +++ Omega-3 fatty acids Evidence on both prevention (cohorts, case-control) and treatment (RCT). Epidemiological data, even quantifiable data, supports protective role of fish consumption, but no meta-analyses on the dose-response are readily available. 4/6 RCT’s have reported therapeutic benefit from omega-3 consumption. In treatment the effective dose is likely to be above what might be gained via fish consumption
Schizophrenia + + N.A. ++ Omega-3 fatty acids Evidence from observational studies is on the disturbances in the fatty acid metabolism, not on differences in intake of fish. 5/6 RCT’s have reported therapeutic benefit from omega-3 consumption. However, most studies used fish-oil as adjunctive treatment, not as monotherapy, which makes quantification difficult.
Attention deficit / hyperactivity disorder (ADHD) + + Omega-3 fatty acids + Omega-3 fatty acids Current evidence does not support the use of omega-3 fatty acids as primary treatment of ADHD (¼ trials found positive effect with a treatment cocktail that contained 480 mg/d of DHA and 16 mg/d of EPA. ¾ trials found no effect with respective or lower dosages). Epidemiological data indicates that there are notable differences in membrane fatty acid composition between healthy and subjects with ADHD.
Eyesight/ vision
Pre-term infants ++ ++ Omega-3 fatty acids ++ Omega-3 fatty acids Supplementation of pre-term-infant formula with long chain fatty acids may improve the development on vision in pre-term infants. However the evidence is not convincing as several null findings also exists. No conclusions can be made on dose-response.
Macular degeneration ++ ++ Fish and omega-3 fatty acids - Epidemiological data on fish intake and AMD suggest a trend toward protective relation. Three studies have found reduced risk of ADM or progression of ADM when consuming fish two of more times/ week. One study group suggested a protective effect even at the consumption level of 1-3 servings/ month. Meta-analyses are not readily available on the subject. One RCT with fish-oil is on-going.

- No data, + Initial findings, ++ Replicate studies, +++ Plenty of data


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