Estrone (E1) is one of the three estrogens, which also includes estriol and estradiol. Estrone is the least abundant of the three and is relevant to health and disease because it is considered the stronger acting estrogen. In post-menopausal women, however, higher levels of estrone when compared to the other estrogens have been implicated in cardiovascular disease, stroke and certain types of cancer. If you are taking estrogen replacement therapy, it is important to follow the balance of the three main estrogens in your body- Estrone (E1), Estradiol (E2), and Estriol (E3). Imbalances in the relationship between estrone and the other two major estrogens are thought to increase the risk for many age-related diseases.