Question

In women with the premenstrual syndrome (PMS), is vitamin B6 (pyridoxine) effective for relieving overall and depressive premenstrual symptoms?

Data sources

Studies were identified by searching MEDLINE (1966 to 1998), EMBASE/Excerpta Medica (1988 to 1996), PsycLIT (1974 to 1997), CINAHL (1982 to 1997), and the Cochrane Controlled Trials Register with the terms premenstrual syndrome, pyridoxine, PMT, LLPDD, and PMDD. Bibliographies of relevant arti-cles were scanned, and pharmaceutical companies were contacted.

Study selection

Published and unpublished studies in any language were selected if they were randomized, double-blind, placebo-controlled trials for which data could be obtained. Studies involving multi-vitamin supplements were included if the supplement contained 50 mg of vitamin B6.

Data extraction

Data were extracted on participants, dose and preparation of vitamin B6, outcome measures, results, withdrawals and side effects, and quality scores. The main outcome was subjective improvement in overall premenstrual symptoms, and a secondary outcome was improvement in depressive premenstrual symptoms. Predetermined quality scores 3 on the Jadad scale and 6 on the authors' rating scale were used to classify high-quality studies.

Main results

10 RCTs with 12 comparisons met the inclusion criteria. Sample sizes ranged from 31 to 434 women (mean 98 women). Doses ranged from 50 mg/d (3 comparisons) to 600 mg/d (1 comparison). Quality scores on the Jadad scale were 1 (3 studies), 2 (4 studies), and 3 (3 studies) points. On the auth-ors' quality rating scale, scores were 3 (2 studies), 4 (5 studies), 5 (2 studies), and 6 (1 study) points. Quality scores were not used to exclude studies in the analysis because few high-quality studies were found. Pooled results showed that vitamin B6 was effective for relieving premenstrual symptoms (combined odds ratio [OR] 1.57, 95% CI 1.40 to 1.77). 1 study led to statistically signifi cant heterogeneity when the 10 studies were pooled (P < 0.001). When this study was removed, the combined OR was 2.32 (CI 1.95 to 2.54). 5 studies reported data on depressive menstrual symptoms and showed a benefit for vitamin B6 (combined OR 2.12, CI 1.80 to 2.48). 1 study led to heterogeneity (P < 0.001), and removal of this study resulted in a combined OR of 1.69 (CI 1.39 to 2.06). The 3 high-quality studies according to the Jadad scale showed a benefit for vitamin B6, whereas the 1 high-quality study according to the authors' quality rating did not show an effect.

Conclusions

In women with the premenstrual syndrome, randomized, double-blind, placebo-controlled trials show that vitamin B6 relieves overall premenstrual and depressive symptoms. However, most of the studies fail to meet some methodologic criteria.

Source of funding: None.

For correspondence: Dr. K.M. Wyatt, Academic Department of Obstetrics and Gynecology, North Staffordshire Hospital, Stoke on Trent ST4 6QG, England, UK. FAX 44-1782-552472.

Abstract and Commentary also published in ACP Journal Club. 1999;131:60.