A new study, published in the New England Journal of Medicine, examines how deficiencies of testosterone and estrogen affect males physiologically.  The study recruited nearly 400 healthy men between the ages of 20 and 50.  These men were given a gel to suppress testosterone and estrogen or to suppress the conversion of these hormones.  They were then assigned to receive one of a number of levels of testosterone or a placebo.  Results showed that men varied on the amount of testosterone they needed to maintain fat, muscle, strength, and sexual function.

However, estrogen deficiency as a whole contributed to increased body fat and declines in sexual function.  The researchers note that these findings are significant because it changes scientific understanding of the hormonal effects of hypogonadism.  By applying the results of this study, doctors that are evaluating and treating related conditions can better use information about the effects of estrogen deficiency.

An analysis of this study by USA Today notes that this research may be surprising because estrogen is generally considered a “female” hormone and is associated with feminine qualities.  Existing, long-standing literature has supported that testosterone decline results in loss of upper body strength, muscle mass, and sex drive.  Given the established nature of this evidence, drug manufacturers have focused on marketing testosterone supplements to these men.  This study complicates the situation by showing that it could actually be an estrogen deficiency that is leading to erectile dysfunction, inhibited libido, and an unfit physique.  Drug companies may have to redirect their strategies to account for this cause.

According to News Medical, estrogens are compounds of steroids that are important for development and functioning.  Generally, they are thought to be necessary for females more than males.  In women, estrogens are primarily produced by the ovaries. After an egg has been released from the follicle and from the placenta, estrogens are secreted by the corpus luteum and are also released by the follicles on the ovaries.

Estrogens are also produced in smaller amounts by other tissues such as the liver, adrenal glands, and the breasts.  The body also synthesizes estrogen through a process that begins with cholesterol and also involves testosterone in the conversion.  Estrogens are used as a part of some oral contraceptives, hormone replacement therapies and other treatment for disorders on the endocrine system.

A recent National Monitor article also disputes assumptions about the benefits of testosterone.  Smaller testicles and lower testosterone levels have been associated with improved nurturing.  In other words, lower testosterone may mean better fathers.