The role for vitamin B-6 as treatment for depression: a systematic review

Background. Major depression is the leading cause of disability worldwide, and among the 10 most frequent indications for using alternative medicine therapies, especially dietary supplements. Objective. To assess the evidence evaluating vitamin B-6 supplementation as treatment for depression. Methods. Medline, Psychinfo, AMED, and Cochrane Controlled Trials Register were searched from database inception through September 2001. All randomized controlled trials, controlled clinical trials, intervention studies, case-control studies, reviews, and case reports examining the evidence behind vitamin B-6 in depression among humans were selected. No limits were placed for demographics or co-morbidities. Only English language papers were abstracted and assessed for trial quality. Two abstractors independently evaluated each study, then reconciled findings. As data were available, between group treatment effect size was noted or, as needed, calculated. When studies reported outcome effects using multiple measures, data were abstracted to permit the greatest possible comparisons among papers. Results. Ten articles met inclusion criteria; three reviews, one case report, five RCTs, and one intervention study. There was no common outcome measure among all studies, eliminating opportunity for direct comparison of effect sizes. As an alternate means of comparison, effects were plotted as they related to the null hypothesis. Conclusion. Viewed as a whole, meaningful treatment effect of vitamin B-6 for depression in general was not apparent. However, examination of papers addressing depression in pre-menopausal women only, reveals a consistent message about the value of using vitamin B-6 supplementation. Further study of vitamin B-6 as independent and adjuvant therapy for hormone related depression in women is indicated.