Probiotics and Omega-3s - Can They Help with Anxiety and Depression?

Anxiety and depression are the two most globally prevalent mental health conditions.

These conditions impact people of all ages, races, and socioeconomic status, affecting a combined 500 million plus people.

Their broad reach and obvious quality-of-life implications mean that scientific interest in complementary management strategies will always be high.

Which brings us to the goal of today’s article.

Omega-3 fatty acids and Probiotics are two of the most popular and efficacious supplement classes on the market. Their potential to improve symptom outcomes in depression and anxiety has been examined reasonably extensively in the scientific literature.  

But does the state of the current evidence support their widespread use in people living with these conditions?

Let’s find out.

A Primer -  How They Might Help

Before diving into the human study data, let’s briefly go through two potential & mutual mechanisms through which probiotics and omega-3s might positively influence brain health.

1. Reduction In Inflammatory Markers:  Omega-3 fatty acids are strongly anti-inflammatory compounds in their own right, whereas the state of one’s gut microbiome (balance vs. dysbiosis) plays a significant role in the inflammatory or anti-inflammatory signaling in the body.
2. Increase in BDNF Production: Scientists believe that both omega-3 fatty acids and probiotics have the potential to boost the production of BDNF (brain-derived neurotrophic factor), a compound that stimulates the reproduction, renewal, and repair of brain cells. 

With that scientific appetizer out of the way, we can now jump into the main course – the human evidence.

Omega-3s For Anxiety & Depression

With growing scientific curiosity around the connection between the anti-inflammatory potential of one’s diet and mental health outcomes, it is unsurprising that omega-3 fatty acids have generated interest in this area.

The long-chain omega-3 fatty acids EPA and DHA are often studied in supplemental form since they are found almost exclusively in fatty fish like salmon, sardines, trout, and mackerel – foods that don’t tend to be widely consumed.

That brings us to a very recently published 2023 systematic review and meta-analysis out of the PLEFA journal, which looked at the results of ten randomized controlled trials totaling over 1,400 participants.

For Depression: EPA/DHA supplements that were composed of at least 60% EPA and between 1-2 grams of total EPA yielded a statistically significant reduction in the severity of depressive symptoms. 

While the meta-analysis cited above did not incorporate a sufficient number of anxiety-focused studies to draw conclusions in this area, a 2018 paper out of JAMA Network Open did.

For Anxiety: In that analysis, a minimum dose of 2 grams per day of EPA/DHA supplements was identified as having the potential to statistically significantly reduce anxiety symptoms in those with a clinical diagnosis.

Summary: There is intriguing but certainly not conclusive evidence that omega-3 supplementation could positively influence measurable symptoms of anxiety and depression, but the state of the evidence is not at a sufficient level to mandatorily recommend omega-3 supplementation to everyone with anxiety or depression.

Additionally, when PLoS One reviewed the data explicitly about younger people (14-24), they did not find compelling evidence that omega-3 fatty acid supplementation meaningfully improved symptoms of either depression or anxiety in that demographic. 

Probiotics For Anxiety & Depression

The growing interest in the immense role of gut-brain communication in mental health outcomes means that probiotics were also inevitable subjects of scientific fascination in this realm.

To that point, The Journal Of Clinical Medicine published a meta-analysis in 2021 which looked at a total of seven eligible experimental studies and determined that, when administered in those taking antidepressant medication, probiotics may contribute to a reduction in depressive symptoms – but this effect was not observed when probiotics were used alone. 

The conclusions reached in that particular analysis mirrored those from a 2019 paper out of Neuroscience and Behavioural Reviews, which found that probiotics yielded small but significant positive effects, which were much more notable in those with a clinical diagnosis. 

As you can see, there is an emerging notion that the potentially beneficial role of either of these supplements may be heavily context-dependent. 

For Anxiety:  The quantity and quality of trials looking at probiotics for anxiety seems to be less than those for depression. Still, from what is available, probiotics also appear to demonstrate some promise in reducing anxiety symptoms.

The dosage and types of probiotics used in these studies vary, and the quantity of evidence does not allow for specific recommendations. However, it is most often multi-strain probiotics that yield measurable benefits for a multi-month period. 

Even so - a certain single strain species, Lactobacillus (L.) plantarum P-8, has been demonstrated to have potential stress-reducing capabilities in a clinical trial exploring its use in stressed adults.

Overall Thoughts

The overwhelming sense I was left with after reviewing the evidence for probiotics and omega-3 used in populations of anxiety and depression sufferers is that these are complex conditions for which it isn’t likely to be the case that any single supplemental intervention is going to lead to life-changing differences in symptoms.

With that being said, there is some evidence to suggest that when used in the right way by the right population, there is a potential symptom reduction benefit to be observed.

How relevant this effect is for those living with anxiety and depression, based on the totality of current evidence, is much harder to say.

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