The effectiveness of fish oil supplementation in depression is still being debated. However, one research team believes the differences in outcomes may be due to the lack of testing omega-3 blood levels in every participant at the start of the study.[1,2]
Another recent study, which tested plasma levels before and after supplementation, found positive results on depression severity that may have been attributed to improved white matter integrity.
In 2009, when Carney et al. compared the effects of omega-3 fatty acids with an antidepressant in patients with depression and coronary heart disease (CHD), they did not find a superior outcome for the use of fish oil supplementation. Upon reviewing their data, they decided to determine whether measuring baseline blood levels of omega-3 fatty acids prior to supplementation might be the predictor of favourable depressive outcomes.
In their recent 2016 study, analysing secondary data from their original study, they found that those with high baseline red blood cell (RBC) levels of EPA and DHA, along with a high EPA and DHA: arachidonic acid (AA) ratio may have better depression symptomology after supplementation than those with low levels prior to taking omega-3 fatty acids.
The authors concluded that omega-3 supplementation may be an effective treatment for depression, but the requisite dosage and duration of treatment may depend on the patient’s baseline level of omega-3 fatty acids.
White matter abnormalities are linked to depressive symptomology. When 16 acutely depressed patients and 12 healthy volunteers were given fish oil supplementation for 6 weeks, there was a trend for greater increases in fractional anisotropy (FA), a measure of directionality of water diffusion, in the white matter of those with major depressive disorders (MDD). Healthy white matter has water movement in the direction of the axon fibre bundles and thus high anisotropy. Abnormalities in FA are reported in MDD.
Researchers also looked at the balance of lipids in the brain and found that the supplementation (which was a total of 4g of fish oil per day: 1.6g EPA and 0.8g DHA) increased DHA percentages in the plasma phospholipid levels of depressed subjects. Increases in EPA and decreases of AA were comparable between both MDD and healthy subject groups. Depression scales after supplementation were also improved.
The authors concluded that ‘increased FA correlated with increased DHA% and decreased depression severity after fish oil supplementation suggests therapeutic effects of omega-3 PUFAs may be related to improvements in white matter integrity.’
- Carney RM, Steinmeyer BC, Freedland KE, et al. Baseline blood levels of omega-3 and depression remission: a secondary analysis of data from a placebo-controlled trial of omega-3 supplements. J Clin Psychiatry 2016;77(2):e138-143. [Abstract]
- Dryden J. Higher blood levels of omega-3 may help depression in heart patients. Health Canal 2016. [Link]
- Chhetry BT, Hezghia A, Miller JM, et al. Omega-3 polyunsaturated fatty acid supplementation and white matter changes in major depression. J Psychiatric Res 2016;75:65-74. [Abstract]
- Carney RM, Freedland KE, Rubin EH, et al. Omega-3 augmentation of sertraline in treatment of depression in patients with coronary heart disease: a randomized controlled trial. JAMA 2009;302(15):1651-1657. [Full Text]