People with bipolar disorder have lower levels of certain omega-3 fatty acids that cross the blood-brain barrier compared to those who do not, according to researchers from Penn State College of Medicine and the National Institutes of Health.
The finding could have implications for dietary interventions for the disorder.
Fatty acids are a major area of interest in bipolar disorder and depression because of their biological importance in the brain.
Studies have shown that fatty acid supplementation may be useful for unipolar depression, but the data has been more mixed for bipolar disorder.
The researchers compared fatty acids in 27 people with symptomatic bipolar disorder and 31 healthy control subjects.
The group measured levels of different forms of the polyunsaturated fatty acids omega-3 and omega-6.
They also collected self-reported information on fatty acid consumption and bipolar medication use. Their results are published in the journal Bipolar Disorders.
Free fatty acids are able to cross the blood-brain barrier, while fatty acids bound to proteins are not.
In the study subjects with bipolar disorder, the ratio of a free-circulating omega-3 fatty acid called EPA to bound EPA was lower than in other people.
Omega-3 fatty acids are a large component of brain-cell membranes and are important for cell-to-cell communication in the brain.
In the study, the ratio of free to bound EPA correlated with clinical bipolar symptoms, specifically mania and tendency towards suicide.
Fatty acids also play an important role in the immune system and the inflammatory system.
“Omega-3 and omega-6 fatty acids can shift the balance of inflammation, which we think is important in bipolar disorder”.
However, the researchers did not find altered ratios of omega-3 to omega-6 fatty acids in bipolar subjects.
Although the researchers did find lower levels of omega-3s in patients with bipolar disorder that correlated with symptoms, it’s too early to advise dietary changes or omega-3 supplementation.
Omega-3 fatty acids are abundant in fish, vegetable oils, nuts — especially walnuts, flax seeds, flaxseed oil and leafy vegetables.
Researchers is currently investigating if modifications in dietary intake of fatty acids could be useful in bipolar disorder.
Citation: Saunders EFH, et al. (2015). Low unesterified:esterified eicosapentaenoic acid (EPA) plasma concentration ratio is associated with bipolar disorder episodes, and omega-3 plasma concentrations are altered by treatment. Bipolar Disorders, 17: 729. DOI: 10.1111/bdi.12337.
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