Lowered omega-3 PUFAs are related to major depression, but not to somatization syndrome

Studies indicated a depletion of omega-3 fatty acid levels and an imbalance between omega-3 and omega-6 PUFAs in depressive patients. Depletion of omega-3 PUFAs may be related to the immune and serotonergic pathophysiologies of depression by alterations in membrane fluidity and modulation of membrane receptors, enzyme activities and carriers. Previous studies also found serotonergic and immunological disturbances in subjects with somatoform symptoms. Based on these findings we aimed to investigate PUFA concentrations and its relations to other biological systems in depressed patients and in patients with somatoform symptoms.

We examined 150 subjects divided in 4 groups, i.e. somatization syndrome; depression; depression and somatization syndrome; controls. Blood samples were analyzed for fatty acids, markers of the serotonergic system and the immune system.

The study was able to replicate earlier findings in patients with depression (lowered omega-3 PUFAs, increased omega-6/omega-3 ratios in serum cholesteryl esters). The somatization syndrome group showed no abnormalities in the mentioned fatty acid levels. Only depressive patients revealed associations between fatty acids with serotonergic and immunological markers.

We used current state diagnoses, and the consideration of lifetime diagnoses and longitudinal studies could highlight further aspects of the reported results.

The findings are further confirming that the concepts of depression and somatoform disorders should not be merged indiscriminately together, even though they often occur together. We conclude that in depression and somatoform syndrome different biological mechanisms seem to be involved.