The relationship between physical activity and 2-hydroxyestrone, 16α-hydroxyestrone, and the 2/16 ratio in premenopausal women (United States)

Abstract

These results indicate that physical activity may modulate estrogen metabolism to favor the weak estrogen, 2-OHE1, thus producing a higher 2/16 ratio. This alteration in estrogen metabolism may represent one of the mechanisms by which increased physical activity reduces breast cancer risk.

Effects of Aerobic Exercise Training on Estrogen Metabolism in Premenopausal Women: A Randomized Controlled Trial

“…In the three early studies (21)(22)(23), sample sizes were small (i.e., five to seven participants per group), menstrual function was not standardized (resulting in comparisons between individuals with and without menstrual dysfunction and women with different reproductive ages), self-reported physical activity measures were used (i.e., swim distance, running mileage, and participation in a varsityrowing program), and the studies used an older version of RIA (21,22) or administration of a labeled tracer (23) to measure estrogen metabolites, which are not as valid as the newer solid-phase enzyme immunoassay (30,36). Methodologic improvements are evident in three more recent studies (24,25,37), namely the use of larger sample sizes, standardized menstrual status, and analysis of estrogen metabolites using a newer solid-phase enzyme immunoassay. However, all have used BMI as a measure of adiposity, which is problematic, especially for more athletic populations.…”

“…However, all have used BMI as a measure of adiposity, which is problematic, especially for more athletic populations. Two studies (24,25) used self-reports of physical activity levels, which suffer from several methodologic issues, particularly overreporting of frequency, duration, and intensity (38). One study (37) used an objective measure of chronic exercise, VO 2max .…”

“…However, when women were split into overweight (BMI, >25) and normal weight (BMI, <25), the association between MET-hours per day and estrogen metabolites remained only for the overweight group. The authors discuss the issues surrounding the measurement of body composition using BMI and that several of those in the higher BMI group were athletic and likely did not have high levels of adiposity, which may account for their findings (24).…”

“…The majority of participants (i.e., 27 of 32) maintained consistent menstrual cycle length within the reference range (24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36) …”

“…Until recently, this idea was based on three small studies, which indicated higher 2-OHE1 levels in more active young women, especially those who develop menstrual dysfunction associated with exercise (21)(22)(23). Two recent cross-sectional studies suggest that higher self-reported physical activity is associated with an increase in levels of 2-OHE1 and 2-OHE1 to 16a-OHE1 ratio; however, this association may have been influenced by body composition (24,25). To date, only one study has examined the effects of an aerobic exercise training intervention on estrogen metabolism using randomized controlled trial methodology, but it was confined to postmenopausal women (26).…”