Trifolium pratense L. · herb
Evidence tier: weak
A traditional women's herb with mild phytoestrogen activity. Useful for perimenopausal hot flushes and as a blood purifying alterative.
The isoflavones biochanin A and formononetin are metabolised to genistein and daidzein, which bind oestrogen receptors, preferentially the beta subtype. That is real receptor level pharmacology and it explains both the plausibility of a hot flush effect and the contraindication in hormone sensitive disease. It does not explain the trial results, which have not reliably shown the effect the mechanism predicts.
Weak for the use it is sold for. The highest tier synthesis is the Cochrane review of phytoestrogens for menopausal vasomotor symptoms (Lethaby et al., 2013, CD001395), which pooled dietary soy, soy extracts and red clover extracts and concluded there is 'no conclusive evidence that phytoestrogen supplements effectively reduce the frequency or severity of hot flushes and night sweats', noting that many trials were small, at high risk of bias, and swamped by a placebo response that itself reduced flush frequency by 1 to 59 percent. NCCIH agrees: studies of red clover for hot flushes 'have had inconsistent results, and some of the studies had a high risk of bias', and 'the research hasn't shown conclusive evidence of benefits for any health condition'. Later non Cochrane meta analyses are more favourable and should be stated honestly: pooling of eight trials found about 1.7 fewer hot flushes per day versus placebo, with the signal concentrated in women having five or more flushes daily, at isoflavone doses of 80 mg or more, at 12 weeks, and in formulations richer in biochanin A. Even the authors of the favourable pooling describe the effect as small and of uncertain clinical relevance. The osteoporosis and cholesterol uses are not established. The safety half matters more than the efficacy half here: red clover is a genuine phytoestrogen, and MSK About Herbs states that people with hormone sensitive cancers should avoid it because of its estrogenic activity.
40 to 80 mg standardised isoflavones daily. Trials that saw any effect used 80 mg or more daily for at least 12 weeks.
Tea: 1 tsp dried flowers per cup, 2 to 3 times daily; or 40 to 80 mg standardised isoflavones daily.
Avoid in hormone sensitive conditions, on hormonal contraceptives, or with anticoagulants.
Pregnancy: avoid
Breastfeeding: avoid
Active compounds: biochanin A, formononetin, genistein, daidzein
Remedies using Red Clover · Browse by body system · Check it against what you take
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.