Fish oil supplements have no effect on anxiety and depression

Summary: Despite common claims that increasing omega-3 consumption will protect against, or reverse, anxiety and depression, researchers report the supplements have little positive effect on mental health.

Source: University of East Anglia

Omega-3 fats have little or no effect on anxiety and depression according to new research from the University of East Anglia.

Increased consumption of omega-3 fats is widely promoted globally because of a common belief that it will protect against, or even reverse, conditions such as anxiety and depression.

But a systematic review published today in the British Journal of Psychiatry, finds that omega-3 supplements offer no benefit.

Omega-3 is a type of fat. Small amounts are essential for good health and can be found in the food that we eat including nuts and seeds and fatty fish, such as salmon.

Omega-3 fats are also readily available as over-the-counter supplements and they are widely bought and used.

The research team looked at 31 trials of adults with and without depression or anxiety. More than 41,470 participants were randomised to consume more long-chain omega-3 fats (fish oils), or maintain their usual intake, for at least six months

They found that the supplements had little or no effect in preventing depression or anxiety symptoms.

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.”

This shows omega 3 pills
Omega 3 fats are also readily available as over-the-counter supplements and they are widely bought and used. The image is adapted from the University of East Anglia news release.

Dr Katherine Deane, 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.”

Funding: The research was funded by the World Health Organisation.

About this neuroscience research article

Source:
University of East Anglia
Media Contacts:
Lisa Horton – University of East Anglia
Image Source:
The image is adapted from the University of East Anglia news release.

Original Research: Open access
“Omega-3 and polyunsaturated fat for prevention of depression and anxiety symptoms: systematic review and meta-analysis of randomised trials”. Lee Hooper et al.
British Journal of Psychiatry doi:10.1192/bjp.2019.234.

Abstract

Omega-3 and polyunsaturated fat for prevention of depression and anxiety symptoms: systematic review and meta-analysis of randomised trials

Background
There is strong public belief that polyunsaturated fats protect against and ameliorate depression and anxiety.

Aims
To assess effects of increasing omega-3, omega-6 or total polyunsaturated fat on prevention and treatment of depression and anxiety symptoms.

Method
We searched widely (Central, Medline and EMBASE to April 2017, trial registers to September 2016, ongoing trials updated to August 2019), including trials of adults with or without depression or anxiety, randomised to increased omega-3, omega-6 or total polyunsaturated fat for ≥24 weeks, excluding multifactorial interventions. Inclusion, data extraction and risk of bias were assessed independently in duplicate, and authors contacted for further data. We used random-effects meta-analysis, sensitivity analyses, subgrouping and Grading of Recommendations, Assessment, Development and Evaluations (GRADE) assessment.

Results
We included 31 trials assessing effects of long-chain omega-3 (n = 41 470), one of alpha-linolenic acid (n = 4837), one of total polyunsaturated fat (n = 4997) and none of omega-6. Meta-analysis suggested that increasing long-chain omega-3 probably has little or no effect on risk of depression symptoms (risk ratio 1.01, 95% CI 0.92–1.10, I2 = 0%, median dose 0.95 g/d, duration 12 months) or anxiety symptoms (standardised mean difference 0.15, 95% CI 0.05–0.26, I2 = 0%, median dose 1.1 g/d, duration 6 months; both moderate-quality evidence). Evidence of effects on depression severity and remission in existing depression were unclear (very-low-quality evidence). Results did not differ by risk of bias, omega-3 dose, duration or nutrients replaced. Increasing alpha-linolenic acid by 2 g/d may increase risk of depression symptoms very slightly over 40 months (number needed to harm, 1000).

Conclusions
Long-chain omega-3 supplementation probably has little or no effect in preventing depression or anxiety symptoms.

Declaration of interest
L.H. and A.A. were funded to attend the World Health Organization Nutrition Guidance Expert Advisory Group (NUGAG) Subgroup on Diet and Health meetings and present review results. The authors report no other conflicts of interest.

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