17-beta Estradiol is the hormone most like the naturally produced estrogen of the ovary, thus making it the hormone of choice for estrogen replacement. The FDA has approved 17-beta Estradiol for use in many commercial preparations. Equally important is how this hormone is delivered to your bloodstream. Once taken, an oral tablet of 17-beta Estradiol is first metabolized in the liver. During which process, unfavorable compounds are created; it is these compounds that impose the vast majority of the risks associated with estrogen replacement. To avoid this first pass through the liver, trans-dermal (topical creams, gels and patches) and sub-dermal (pellet implants) applications are preferred.