Regular and long-term intake of omega-3 fatty acid-rich cod liver oil may protect people from symptoms of depression, says a large study published in the Journal of Affective Disorders. In 21,835 Norwegian subjects aged between 40 and 49 and 70 and 74 years, the prevalence of depressive symptoms was 29 per cent lower in regular cod liver oil users than the rest of the population.
"In this large population based cross-sectional study we found that daily use of cod liver oil was negatively associated with high levels of depressive symptoms and that the prevalence of such depressive symptoms decreased with the duration of cod liver oil use," wrote lead author Maria Baroy Raeder from Haukeland University Hospital
Baroy Raeder and co-workers used data from the population based cross-sectional health survey "The Hordaland Health Study '97-'99" (HUSK), and report that 8.9 per cent of subjects used cod liver oil daily.
"The users of cod liver oil were significantly less likely to have depressive symptoms than non-users after adjusting for multiple possible confounding factors (29 per cent reduction)," wrote the researchers.
They also report that length of regular cod liver oil supplementation was found to influence the prevalence of high levels of depressive symptoms - the longer the duration of supplementation, the lower the prevalence of symptoms of depression.
The study does have several limitations, most notably the lack of dietary data that could have affected the results. In addition, socio-economic factors were not accounted for in the study, which also may affect the overall health and mental state of the subjects. The researchers, therefore, stressed that the results should be interpreted with care.
"To confirm such a possible protective effect, randomized controlled trials are needed," concluded the researchers.
Bonnie - limitations on this study, yes. However, it was such a large population study and was done in a country with very little yearly sun exposure. It confirms what we have been saying: the combination of omega-3's and vitamin D for mood is dynamite!