A recently published meta-analysis concludes that omega-3 oil supplements might reduce symptoms of anxiety for some people.

Anxiety is one of the most common psychiatric symptoms in the United States.

It can appear as a standalone anxiety disorder or as part of another mental disorder, such as depression.

Pharmaceutical interventions, such as serotonin reuptake inhibitors, can treat anxiety.

However, people with anxiety disorders are often concerned about side effects and dependence.

Other options include talking therapies, but these are time-consuming and can be costly.

An estimated 1 in 5 adults in the US develop an anxiety disorder each year, so finding a safe, cost-effective way to manage anxiety would be of great benefit to millions of people.

Fish oils and anxiety

Omega-3 polyunsaturated fatty acids (PUFAs) are present in fish oils. Over the years, researchers have ascribed a wide range of health benefits to them, but not all are supported by evidence.

In recent years, some scientists have tested omega-3's potential to help in the treatment of psychiatric conditions, including mood and anxiety disorders.

Studies investigating the anti-anxiety effects of omega-3 PUFAs in animal models have seen some success; for instance, a study in rats found that a diet rich in a PUFA called eicosapentaenoic acid reduced anxiety-like behaviors.

In humans, research has shown a relationship between PUFA levels and anxiety. For instance, one study found that people with anxiety disorders have lower levels of circulating omega-3 PUFAs.

Another showed that omega-3 supplements reduced inflammation and anxiety in medical students during exams.

These studies and others, though, have been limited by their small size. To rectify this, researchers recently carried out the first systematic review on this topic. They explain their aim:

"[W]e examined," they point out, "the anxiolytic effects of omega-3 PUFAs in participants with elevated anxiety symptoms in the results of clinical trials to determine the overall efficacy of omega-3 PUFAs for anxiety symptoms irrespective of diagnosis."

The researchers took data from 19 clinical trials including a total of 1,203 participants. After analysis, their findings supported their initial theory. Although the studies varied significantly in the type of participants that were involved and the ways that anxiety was measured, they saw a significant reduction in anxiety in the groups treated with omega-3s compared with the placebo groups.

Most of the studies demonstrated a positive effect of omega-3 PUFAs on anxiety, even though not all effect sizes were significant. However, when the data were pooled, the combined effect was statistically significant.

"This review indicates that omega-3 PUFAs might help to reduce the symptoms of clinical anxiety. Further well-designed studies are needed in populations in whom anxiety is the main symptom."

Interestingly, the positive effects of omega-3s were particularly pronounced for people who had clinical diagnoses of psychiatric conditions.

More work is now needed

Before omega-3s are brought into wider use, the authors suggest that more large-scale studies will be needed. Exactly how they these fatty acids might impart their beneficial effects is another question that will need to be answered.

Omega-3 PUFAs are present in brain membranes and, as the authors write, they may "interfere with and possibly control several neurobiological processes, such as neurotransmitter systems, neuroplasticity, and inflammation."

This could help explain why they have an impact on psychiatric symptoms, but a lot more research will be needed to unpick the exact mechanisms involved.

The study authors are clear that their analysis has some limitations; in particular, the relatively small sample size. They warn that "the results should not be extrapolated without careful consideration."

More research is sure to follow. If an intervention as simple as omega-3 supplementation could reduce levels of anxiety, it would have the potential to ease suffering for a great many people.