This pilot study will begin to address whether gut microbiota change with estrogen suppression. Specifically, the investigators will test whether gut microbial diversity and abundance change in response to estrogen suppression and consumption of dietary flaxseed. To test this possibility the investigators will recruit premenopausal women (age 20-40 years old)and collect fecal samples before and after 1 month of estrogen suppression with GnRH agonist. The investigators will analyze the gut microbiota in response to estrogen loss and whether this differs with the consumption of flaxseed.