Herbal and dietary therapies for primary and secondary dysmenorrhoea

Department of Obstetrics and Gynecology, National Women's Hospital, Claude Road, Epsom, Auckland, New Zealand, 1003. ml.wilson@auckland.ac.nz

BACKGROUND: Dysmenorrhoea refers to the occurrence of painful menstrual cramps of uterine origin and is a common gynecological complaint. Common treatment for dysmenorrhoea is medical therapy such as nonsteroidal anti-inflammatories (NSAIDs) or oral contraceptive pills (OCPs) which both work by reducing myometrial activity (contractions of the uterus). The efficacy of conventional treatments such as nonsteroidals is considerable; however the failure rate is still often 20-25%. Many consumers are now seeking alternatives to conventional medicine and research into the menstrual cycle suggests that nutritional intake and metabolism may play an important role in the cause and treatment of menstrual disorders. Herbal and dietary therapies number among the more popular complementary medicines yet there is a lack of taxonomy to assist in classifying them. In the US, herbs and other phytomedicinal products (medicine from plants) have been legally classified as dietary supplements since 1994. Included in this category are vitamins, minerals, herbs or other botanicals, amino acids and other dietary substances. For the purpose of this review we use the wider term herbal and dietary therapies to include the assorted herbal or dietary treatments that are classified in the US as supplements and also the phytomedicines that may be classified as drugs in the European Union.

OBJECTIVES: To determine the efficacy and safety of herbal and dietary therapies for the treatment of primary and secondary dysmenorrhoea when compared to each other, placebo, no treatment or other conventional treatments (e.g. NSAIDS). SEARCH STRATEGY: Electronic searches of the Cochrane Menstrual Disorders and Subfertility Group Register of controlled trials, CCTR, MEDLINE, EMBASE, CINAHL, Bio extracts, and PsycLIT were performed to identify relevant randomized controlled trials (RCTs). The Cochrane Complementary Medicine Field's Register of controlled trials (CISCOM) was also searched. Attempts were also made to identify trials from the National Research Register, the Clinical Trial Register and the citation lists of review articles and included trials. In most cases, the first or corresponding author of each included trial was contacted for additional information.

SELECTION CRITERIA: The inclusion criteria were RCTs of herbal or dietary therapies as treatment for primary or secondary dysmenorrhoea vs each other, placebo, no treatment or conventional treatment. Interventions could include, but were not limited to, the following; vitamins, essential minerals, proteins, herbs, and fatty acids. Exclusion criteria were: mild or infrequent dysmenorrhoea or dysmenorrhoea from an IUD.

DATA COLLECTION AND ANALYSIS: Seven trials were included in the review. Quality assessment and data extraction were performed independently by two reviewers. The main outcomes were pain intensity or pain relief and the number of adverse effects. Data on absence from work and the use of additional medication was also collected if available. Data was combined for meta-analysis using Peto odds ratios for dichotomous data or weighted mean difference for continuous data. A fixed effects statistical model was used. If data suitable for meta-analysis could not be extracted, any available data from the trial was extracted and presented as descriptive data.

MAIN RESULTS:

MAGNESIUM: Three small trials were included that compared magnesium and placebo. Overall magnesium was more effective than placebo for pain relief and the need for additional medication was less. There was no significant difference in the number of adverse effects experienced.

VITAMIN B6: One small trial of vitamin B6 showed it was more effective at reducing pain than both placebo and a combination of magnesium and vitamin B6.

MAGNESIUM AND VITAMIN B6: Magnesium was shown to be no different in pain outcomes from both vitamin B6 and a combination of vitamin B6 and magnesium by one small trial. The same trial also showed that a combination of magnesium and vitamin B6 was no different from placebo in reducing pain.

VITAMIN B1: One large trial showed vitamin B1 to be more effective than placebo in reducing pain.

VITAMIN E: One small trial comparing a combination of vitamin E (taken daily) and ibuprofen (taken during menses) versus ibuprofen (taken during menses) alone showed no difference in pain relief between the two treatments.

OMEGA-3 FATTY ACIDS: One small trial showed fish oil (omega-3 fatty acids) to be more effective than placebo for pain relief.

JAPANESE HERBAL COMBINATION: One small trial showed the herbal combination to be more effective for pain relief than placebo, and less additional pain medication was taken by the treatment group.

REVIEWER'S CONCLUSIONS: Vitamin B1 is shown to be an effective treatment for dysmenorrhoea taken at 100 mg daily, although this conclusion is tempered slightly by its basis on only one large RCT. Results suggest that magnesium is a promising treatment for dysmenorrhoea. It is unclear what dose or regime of treatment should be used for magnesium therapy, due to variations in the included trials, therefore no strong recommendation can be made until further evaluation is carried out. Overall there is insufficient evidence to recommend the use of any of the other herbal and dietary therapies considered in this review for the treatment of primary or secondary dysmenorrhoea.