“Estrogen” is a general term that includes at least three human hormone substances; estrone (E1), estradiol (e2), and estriol (e3). These substances are responsible for most of the female characteristics and they are extremely important in pregnancy and the menstrual cycle. They are predominantly secreted by the ovaries. However, many parts of the body have the ability to use natural precursors to make one or more of the estrogens. While they are predominantly associated with females, they are also found in males, in much smaller quantities.

Estrogen levels rise and fall throughout the normal cycle. There are large amounts present during pregnancy.

Estrogens are sometimes called, “proliferative hormones”, because of the action they exert on tissue. Proliferative refers to growing and multiplying. The action of estrogen causes cells to divide and multiply. They are associated with “roundness” and “curves”, attributes generally associated with the female body. Men usually have far less estrogen than women and their bodies are more angular.

Estrogens production declines with age, but does not fall to zero. While the ovaries stop releasing viable eggs at menopause, the body continues to make estrogens in other tissues and organs – the skin, for example. They are necessary for healthy living.

Many drug products on the market are advertised as being replacements for human hormones. Some of them are actually derived from other animals. Others are made from chemicals. While they exert some of the actions of real human hormones, they are not identical to what are made in the human body. This has been the basis for many disagreements about hormone replacement therapy (HRT) – which began to gain popularity in the 1960s.

It is possible to make estrogens in a laboratory that are chemically identical to the substances made in the human body. These are referred to as “bio-identical” hormones (BHRT). When needed, it is far more logical to use bio-identical hormones as supplements than those that are “close” but not exact duplicates.