In the Journals

Healthy diet can reduce depressive symptoms

Image of Joseph Firth 2019
Joseph Firth

Dietary interventions can significantly reduce depressive symptoms, according to results from a systematic review and meta-analysis published in Psychosomatic Medicine.

"Many recent large-scale analyses have examined how exercise can benefit mental health, and yet none have looked at the overall evidence for using dietary improvement to improve mental health — even though diet is obviously a very important aspect of a healthy lifestyle separate to exercise,” Joseph Firth, PhD, of the NICM Health Research Institute, Western Sydney University, Australia, and the psychology and mental health division, University of Manchester, U.K., told Healio Psychiatry.

The researchers conducted a systematic review of online databases for all randomized controlled trials of dietary interventions reporting changes in depressive and/or anxiety symptoms in clinical and nonclinical populations. Then, they performed random-effects meta-analyses to determine the effects of dietary interventions vs. control conditions on these symptoms.

Overall, 16 studies with outcome data for 45,826 participants were included in the analyses, 15 of which examined patients with nonclinical depression.

The results showed that dietary interventions significantly eased depressive symptoms compared with control conditions, with a small pooled effect (g = 0.275; 95% CI, 0.1-0.45). Heterogeneity was significant across the study data (I² = 89.4%).

Food high in fiber 
Dietary interventions can significantly reduce depressive symptoms, according to results from a systematic review and meta-analysis.
Source: Adobe Stock

The investigators observed similar effects when assessing high-quality trials (g = 0.321; 95% CI, 0.12-0.53), and when compared with inactive (g = 0.308; 95% CI, 0.02-0.6) and active controls (g = 0.174; 95% CI, 0.01-0.34). However, they found dietary interventions did not influence anxiety (g = 0.1; 95% CI, - 0.04-0.24).

Analysis of the one study that used a clinically depressed sample (n = 67) revealed a significantly greater decrease in depressive symptoms from a 12-week modified Mediterranean diet intervention when compared with “social support,” according to the results.

In addition, studies with only female samples showed significantly greater benefits in depressive and anxiety symptoms from dietary interventions.

“The take-home message from our findings would be that all types of healthy diets seemed to have similar effects on mental health — this includes weight loss diets for obese individuals, or nutrient-boosting diets aimed at increasing health food intake — with no significant differences between the different diet types,” Firth told Healio Psychiatry.

“To me, this would suggest that just making simple changes (like reducing takeaways and junk food and increasing intake of vegetables) seem sufficient for boosting mood,” he continued. “Any extreme diets are probably completely unnecessary for the average individual.”

Image of Brendon Stubbs
Brendon Stubbs

Furthermore, these findings add to mounting evidence that supports lifestyle interventions for boosting mood, Brendon Stubbs, PhD, of the Institute of Psychiatry, Psychology & Neuroscience at King's College London, said in the press release.

"Specifically, our results within this study found that when dietary interventions were combined with exercise, a greater improvement in depressive symptoms was experienced by people,” Stubbs said. “Taken together, our data really highlight the central role of eating a healthier diet and taking regular exercise to act as a viable treatment to help people with low mood." – by Savannah Demko

Disclosures: Firth reports support from a Blackmores Institute Fellowship. Stubbs reports support from the Health Education England and the National Institute for Health Research HEE/NIHR ICA Program Clinical Lectureship.

Image of Joseph Firth 2019
Joseph Firth

Dietary interventions can significantly reduce depressive symptoms, according to results from a systematic review and meta-analysis published in Psychosomatic Medicine.

"Many recent large-scale analyses have examined how exercise can benefit mental health, and yet none have looked at the overall evidence for using dietary improvement to improve mental health — even though diet is obviously a very important aspect of a healthy lifestyle separate to exercise,” Joseph Firth, PhD, of the NICM Health Research Institute, Western Sydney University, Australia, and the psychology and mental health division, University of Manchester, U.K., told Healio Psychiatry.

The researchers conducted a systematic review of online databases for all randomized controlled trials of dietary interventions reporting changes in depressive and/or anxiety symptoms in clinical and nonclinical populations. Then, they performed random-effects meta-analyses to determine the effects of dietary interventions vs. control conditions on these symptoms.

Overall, 16 studies with outcome data for 45,826 participants were included in the analyses, 15 of which examined patients with nonclinical depression.

The results showed that dietary interventions significantly eased depressive symptoms compared with control conditions, with a small pooled effect (g = 0.275; 95% CI, 0.1-0.45). Heterogeneity was significant across the study data (I² = 89.4%).

Food high in fiber 
Dietary interventions can significantly reduce depressive symptoms, according to results from a systematic review and meta-analysis.
Source: Adobe Stock

The investigators observed similar effects when assessing high-quality trials (g = 0.321; 95% CI, 0.12-0.53), and when compared with inactive (g = 0.308; 95% CI, 0.02-0.6) and active controls (g = 0.174; 95% CI, 0.01-0.34). However, they found dietary interventions did not influence anxiety (g = 0.1; 95% CI, - 0.04-0.24).

Analysis of the one study that used a clinically depressed sample (n = 67) revealed a significantly greater decrease in depressive symptoms from a 12-week modified Mediterranean diet intervention when compared with “social support,” according to the results.

In addition, studies with only female samples showed significantly greater benefits in depressive and anxiety symptoms from dietary interventions.

“The take-home message from our findings would be that all types of healthy diets seemed to have similar effects on mental health — this includes weight loss diets for obese individuals, or nutrient-boosting diets aimed at increasing health food intake — with no significant differences between the different diet types,” Firth told Healio Psychiatry.

“To me, this would suggest that just making simple changes (like reducing takeaways and junk food and increasing intake of vegetables) seem sufficient for boosting mood,” he continued. “Any extreme diets are probably completely unnecessary for the average individual.”

Image of Brendon Stubbs
Brendon Stubbs

Furthermore, these findings add to mounting evidence that supports lifestyle interventions for boosting mood, Brendon Stubbs, PhD, of the Institute of Psychiatry, Psychology & Neuroscience at King's College London, said in the press release.

"Specifically, our results within this study found that when dietary interventions were combined with exercise, a greater improvement in depressive symptoms was experienced by people,” Stubbs said. “Taken together, our data really highlight the central role of eating a healthier diet and taking regular exercise to act as a viable treatment to help people with low mood." – by Savannah Demko

Disclosures: Firth reports support from a Blackmores Institute Fellowship. Stubbs reports support from the Health Education England and the National Institute for Health Research HEE/NIHR ICA Program Clinical Lectureship.

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