Estradiol is a form of the female sex hormone estrogen, and rats with low levels of it retain more water, according to a new study published in the American Journal of Physiology.

Water retention is the primary reason why many women will feel bloated at one point or another. Hormonal changes are believed to influence the body’s water balance, but the present study specifically hones in on sex hormones. These hormones regulate what’s called aquaporin 2 (AQP2), or the water-absorbing channels located along the kidney ducts. Researchers cited that kidneys control “the amount of water reabsorbed from the blood they filter.”

For this study, researchers studied female rats without ovaries, which means these rats urinated less and had more AQP2 channels than female rats with their ovaries. When treating these rats with estradiol, they experienced an increase in urine output and a decrease in AQP2 channels. This suggests estradiol acts as a direct inhibitor of AQP2. Put another way: low levels of estradiol may cause greater water retention.

“These findings suggest that changes in estradiol levels, such as during menopause or following reproductive surgeries, may contribute to dysregulation of water homeostasis in women,” the researchers concluded.

Estrogen is a naturally occurring hormone. In order to raise levels of it, women will have to see their doctor. Oftentimes, doctors will suggest hormone replacement therapy, which is a catch-all for available medications containing female hormones. There are, of course, risks to consider, but the Mayo Clinic suggests the benefits may outweigh the risks. Hormone therapy not only increases estrogen, but it lessens symptoms of menopause, like moderate to severe hot flashes.

But when we’re talking about something like water retention, the Mayo Clinic has a few quick fixes to lessen the chances of this happening. Physical activity is one, especially for women; prior research shows women who regularly work out report fewer PMS symptoms, chief among them being bloating. This suggestion sits next to reduced salt intake, which can cause your body to retain more water. The counterintuitive solution for increased salt intake is to actually drink more water; this flushes it out your system.

Source: Cheema MU, et al. Estradiol regulates AQP2 expression in the collecting duct - a novel inhibitory role for estrogen receptor alpha. American Journal of Physiology. 2015.

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