Is walnut consumption effective in improving mood among young adults?
Date of publication of the randomized controlled trial: 2016
Design
Randomized controlled trial (RCT).
Participants
64 college students aged 18 to 25 years, without known food allergies (mean age: 20.6 years for walnut group; 22.6 years for placebo group). The authors did not report gender proportion of the participants.
Intervention
Three slices of banana bread with walnuts were consumed every day for 8 weeks. Banana bread with walnuts contained 2 servings (60g) of ground English Walnuts as dietary supplementation. Participants were asked to maintain their usual activities and other lifestyle habits throughout the duration of the study.
Comparator
Comparison: Walnuts versus placebo. Placebo referred to 8 weeks of banana bread without walnuts.
Major Outcomes
Outcome 1: Intensity of mood disturbance for both sexes as assessed by the Profile of Mood States(POMS) questionnaire after 8 weeks of intervention.
Settings
This study was performed in an outpatient setting.
Comparison    Walnuts versus placebo
Main Results
Compared to placebo, walnuts did not show significant changes in mood as assessed by POMS with both genders (p=0.267) and in females (p=0.982). However, walnuts showed a significant improvement in the POMS score in males (p=0.043).
Comparison: Walnuts versus placebo in young adults
Outcomes No. of studies (Total number of participants) Mean score/No. of participants Heterogeneity test (I2) MD (95% CI) p value Overall quality of evidence*
Intervention Comparator
Both sexes:
1 1 (49) 33.5/not reported 37.9/not reported Not applicable as there is only 1 study. -11.6 (-32.4 to 9.2) 0.267 Low
Males:
1 1 (20) 28.9/not reported 39.9/not reported Not applicable as there is only 1 study. -27.5 (-54.0 to -1.00) 0.043 Moderate
Females:
1 1 (29) 35.7/not reported 35.6/not reported Not applicable as there is only 1 study. 0.4 (-32.3 to 33.0) 0.982 Low
Keys: MD = mean difference, CI = confidence interval.
Comparison    Walnuts versus placebo
Main Results
Compared to placebo, walnuts did not show significant changes in mood as assessed by POMS with both genders (p=0.267) and in females (p=0.982). However, walnuts showed a significant improvement in the POMS score in males (p=0.043).
Comparison: Walnuts versus placebo in young adults
Outcomes Both sexes: 1 Males: 1 Females: 1
No. of studies (Total number of participants) 1 (49) 1 (20) 1 (29)
Mean score/No. of participants Intervention 33.5/not reported 28.9/not reported 35.7/not reported
Comparator 37.9/not reported 39.9/not reported 35.6/not reported
MD (95% CI) -11.6 (-32.4 to 9.2) -27.5 (-54.0 to -1.00) 0.4 (-32.3 to 33.0)
p value 0.267 0.043 0.982
Overall quality of evidence* Low Moderate Low
Keys: MD = mean difference, CI = confidence interval.
Conclusion
Benefits
Compared to placebo, walnuts are more effective in improving mood among healthy males. However, no significant effect on mood was observed in females. For outcome 1 in both sexes and in females, the overall quality of evidence is low. Further research is likely to have an important impact on our confidence in this estimate of effect. For outcome 1 in males, the overall quality of evidence is moderate. Further research is fairly likely to have an important impact on our confidence in this estimate of effect.
Harms
The authors did not report details of adverse events.
Link to Original Article
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5133056/
The synopsis is based on the following article:
Pribis P. Effects of Walnut Consumption on Mood in Young Adults-A Randomized Controlled Trial. Nutrients. 2016 Oct 25;8(11).


* Interpretation of quality assessment results:
• Very low: Further research is most likely to have an important impact on our confidence in this estimate of effect.
• Low: Further research is likely to have an important impact on our confidence in this estimate of effect.
• Moderate: Further research is fairly likely to have an important impact on our confidence in this estimate of effect.
• High: Further research is unlikely to have an important impact on our confidence in this estimate of effect.
• Very high: Further research is most unlikely to have an important impact on our confidence in this estimate of effect.

Details of assessment method can be found at Chung VC, Wu XY, Ziea ET, Ng BF, Wong SY, Wu JC. Assessing internal validity of clinical evidence on effectiveness of CHinese and integrative medicine: Proposed framework for a CHinese and Integrative Medicine Evidence RAting System (CHIMERAS). European Journal of Integrative Medicine. 2015 Aug 31;7(4):332-41.