Forty women (mean age, 32 years) with primary infertility of at least 2 years' duration (mean, 4.7 years), and mild or minimal endometriosis diagnosed by laparoscopy, were randomly assigned to receive, in blind fashion (nature of blinding not specified), bee propolis (500 mg twice a day) or placebo for 9 months. Twelve (60%) of 20 women in the active-treatment group became pregnant, compared with 4 (20%) of 20 in the placebo group (p < 0.001). No side effects were reported.

Comment: Propolis is a resinous substance that bees collect from the leaf buds and bark of to repair damage to their hives and to protect the hive from disease. The results of the present study suggest that bee propolis is an effective treatment for infertility associated with mild or minimal endometriosis. Although the mechanism of action is not known, bee propolis has a number of pharmacological actions, including inhibition of aromatase, an enzyme that plays a role in estrogen metabolism.

Ali AFM, Awadallah A. Bee propolis versus placebo in the treatment of infertility associated with minimal or mild endometriosis: a pilot randomized controlled trial. A modern trend. Fertil Steril 2003;80(Suppl 3):S32.