Effects of Vitamin and Mineral Supplementation on Stress, Mild Psychiatric Symptoms, and Mood in Nonclinical Samples: A Meta-Analysis

Objective: Biochemical processes in the brain affect mood. Minor dietary inadequacies, which are responsible for a small decline in an enzyme's efficiency, could cumulatively influence mood states. When diet does not provide an optimal intake of micronutrients, supplementation is expected to benefit mood. This meta-analysis evaluated the influence of diet supplementation on mood in non-clinical samples. Methods: Databases were evaluated and studies were included if they considered aspects of stress, mild psychiatric symptoms, or mood in the general population; were randomized and placebo-controlled; evaluated the influence of multivitamin/mineral supplements for at least 28 days. Eight studies that met the inclusion criteria were integrated using meta-analysis. Results: Supplementation reduced the levels of perceived stress (standard mean difference [SMD] = 0.35; 95% confidence interval [CI] = 0.47-0.22; p = .001), mild psychiatric symptoms (SMD = 0.30; 95% CI = 0.43-0.18; p = .001), and anxiety (SMD = 0.32; 95% CI = 0.48-0.16; p < .001), but not depression (SMD = 0.20; 95% CI = 0.42-0.030; p < .089). Fatigue (SMD = 0.27; 95% CI = 0.40-0.146; p < .001) and confusion (SMD = 0.225; 95% CI = 0.38-0.07; p < .003) were also reduced. Conclusions: Micronutrient supplementation has a beneficial effect on perceived stress, mild psychiatric symptoms, and aspects of everyday mood in apparently healthy individuals. Supplements containing high doses of B vitamins may be more effective in improving mood states. Questions about optimal levels of micronutrient intake, optimal doses, and active ingredients arise.