Omega-3 fatty acids have long been consumed to the benefit of our heart health and ameliorating cardiovascular disease. It has also been claimed to help treat depression. A lot of marketing effort goes into promoting the benefits of omega-3 fatty acid supplementation – not least this web-site. Essential fatty acids are found predominantly in nuts and fish oils. Salmon and krill are very good sources for example.
Depression, a common debilitating psychiatric illness is characterized by sadness, hopelessness, and loss of interest. It is a major public health concern. As the third most common cause of disability in high-income countries, depression is associated with disability, functional decline, and increased mortality. It affects about 264 million people worldwide, and contributes greatly to the global disease burden.
Recent research now claims to show that a serious rethink is needed on the supposed power of omega-3 fatty acids to alleviate and reduce a range of mental health issues. It clearly has not been good day for this supplement although the role in heart health is not being questioned.
Early research on omega-3 fatty acids
Early studies looked at a variety of effects associated with bipolar disorder, depressive disorder and other mood problems. For example, a group of participants suffering with depression had a longer period of remission when taking omega-3 fatty acids than the control group given olive oil (Stoll et al., 1999a). However, low potency means large doses and a number of capsules are needed daily, as reported by a review (Stoll et al., 1999b). The same review found a positive association between omega-3 and depression in 13 of 19 studies reviewed (Stoll et al., 1999b). Trials performed in patients with major depressive disorders who also received their normal treatment, were given 9.6g per day of omega-3 PUFAs. Supplementation significantly decreased scores on a 21-item depression scale compared to the placebo group (p<0.001) (Su et al., 2002).
Several studies have also shown benefits in healthy individuals. Omega-3 supplementation raised the POMS index and suppressed feelings of anger, hatred, fatigue, confusion and depression among participants receiving capsules containing 2.8g omega-3 PUFA per day at 5 and 10 weeks in 2 separate studies (Fontani et al., 2005). However other studies have reported no effect of on depressed mood (Rogers et al., 2008).
A recent review concluded that there was currently not enough evidence to determine if omega PUFAs altered mood in healthy individuals (Gorby et al., 2010) but it has continued to excite interest amongst those researching the role of fatty acid in health. So much however for this early research.
In 2016, researchers from Harvard and Melbourne University in Australia asserted that taking omega-3 significantly improved mood when combined with antidepressants versus a placebo. They reasoned that omega-3 fatty acids cross into brain cells easily and affect molecules that affect mood inside the brain.
In a separate examination, it is also thought omega-3 fatty acids relieve depression because of their significant anti-inflammatory activity.
Questioning the benefits of omega-3 fatty acids
Scientists at the University of East Anglia are asking us to rethink the value of omega-3 fatty acids in the role of alleviating mental health issues. They looked carefully at 31 clinical trials.
Their over-riding conclusion was that taking omega-3 supplements only cut the risk of depression by just one per cent for depression and there was little benefit in treating anxiety.
At least 41,000 subjects were examined in all those 31 studies. The researchers split them into two main groups. One group increased their overall omega-3 intake by taking fish oil supplements whilst the other kept their consumption at the usual level.
The scientists examined indicators of mental health over the first 24 week period They looked at primary indicators including depression diagnosis and secondary indicators including carer stress, self-harm and quality of life which were recorded in questionnaires. Whilst taking such fatty acids is good for general health it appears there was no real benefit on reducing anxiety or depression.
Only one trial appeared to show a correlation between consumption and anxiety and there was actually no change.
The research was published in the British Journal of Psychiatry and financed by the World Health Organisation.
Lead author Dr. Lee Hooper, from UEA’s Norwich Medical School, said:
“Our previous research has shown that long-chain omega-3 supplements, including fish oils, do not protect against conditions such as heart disease, stroke, diabetes or death.
“This large systematic review included information from many thousands of people over long periods. Despite all this information, we don’t see protective effects.
“The most trustworthy studies consistently showed little or no effect of long-chain omega-3 fats on depression or anxiety, and they should not be encouraged as a treatment.”
Dr Katherine Deane, co-author from UEA’s School of Health Sciences, said:
“Oily fish can be a very nutritious food as part of a balanced diet.
“But we found that there is no demonstrable value in people taking omega-3 oil supplements for the prevention or treatment of depression and anxiety.
“Considering the environmental concerns about industrial fishing and the impact it is having on fish stocks and plastic pollution in the oceans, it seems unhelpful to continue to swallow fish oil tablets that give no benefit.”
References
Gorby, H.E., Brownawell, A.M., Falk, M.C. (2010). Do specific dietary constituents and supplements affect mental energy? Review of the evidence. Nutr. Rev. 68 (12) pp. 697-718
Rocha Araujo, D.M., Vilarim, M.M., Nardi, A.E. (2010) What is the effectiveness of the use of polyunsaturated fatty acid omega-3 in the treatment of depression? Expert Rev Neurother 10 (7) pp. 1117-29
Rogers, P.J., Appleton, K.M., Kessler, D., et al. (2008). No effect of n-3 long chain polyunsaturated fatty acid (EPA and DHA) supplementation on depressed mood and cognitive function: a randomised controlled trial. Brit. J. Nutrition 99 pp. 421-31
Stoll, A.L., Severus, W.E., Freeman, M.P., Rueter, S., Zboyan, H.A., Diamond, E., Cress, K.K., Marangell, L.B., (1999a). Omega 3 Fatty Acids in Bipolar Disorder. Arch Gen Psychiatry 56 pp. 407-412.
Stoll, A.L., Locke, C.A., Marangell, L.B., Severus, W.E. (1999b). Omega-3 fatty acids and bipolar disorder: a review. Prostaglandins, Leukotrienes and Essential Fatty Acids 60 (5&6) pp. 329-337.
Su, K.-P., Huang, S.-Y., Chiu, C.-C., Shen, W.W. (2002) Omega-3 Fatty acids in major depressive disorder. A preliminary double-blind, placebo-controlled trial. European Neuropsychopharmacology 13 pp. 267-71
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