A study of lavender and tea tree oils on postmenopausal FSH levels and hot flash severity

Abstract

1516 Background: Products containing lavender and tea tree oil have been linked to prepubertal male gynecomastia.(N Engl J Med 356:479–485) This implies that these products may be phytoestrogens, or plant products with estrogenic effects. Exogenous estrogens increase the risk of developing breast cancer and could counteract benefit from adjuvant hormonal manipulations in women with a history of breast cancer. We designed a study to determine the effects of lavender and tea tree oil on healthy postmenopausal women's FSH as a means to determine the estrogenic effect of both products. Hot flashes are a side effect of decreased endogenous estrogen, and in this study we used hot flash severity as an additional assay of estrogenic effect. Methods: Lavender lotion and tea tree oil products were generously donated by The Body Shop. Nine healthy postmenopausal women suffering from hot flashes were asked to apply lavender lotion and tea tree oil according to product directions for a week each, with a washout period in between. Participants were menopausal with baseline FSH > 26 IU/mL. Serum FSH was obtained at baseline, after each lotion and after the washout period. Participants also recorded daily hot flash number and severity. Average daily hot flash severity was calculated for each patient during each period, with lotion use periods compared to Paired, 2-tailed T-tests were used to compare average hot flash severity for each participant as well as FSH values as compared to the baseline obtained before it. Results: Compliance was excellent. No significant differences were seen between time periods with either product for either measure. In no case did FSH dip to premenopausal levels. No indication of improvement in hot flash frequency or severity was seen. Conclusions: In our population, the lavender and tea tree oil products showed no estrogenic effects. This is similar to clinical trials of phytoestrogens, which as used by humans are not potent enough to affect FSH or hot flash severity. Both lotions can probably be used without increasing the risk of recurrent or de novo breast cancer. We intend one more study period in which participants will use a large daily amount of lavender lotion, again tracking hot flash severity and FSH. No significant financial relationships to disclose.