Women Win This One: Estrogen Protects Against the Flu

Men better start loading up on vitamin C because new research says that women are already naturally protected against the flu.

A person becomes sick when a virus enters a cell and replicates inside the host cell. The more copies of the virus, the worse the severity. Then the virus can make its way through the body and potentially be passed on between people. But as it turns out, the female sex hormone estrogen inhibits the influenza A virus’ ability to replicate.

Researchers examined nasal cells (since these are the cells that the flu virus primarily infects) from male and female donors. Then the cells were exposed to the flu virus, estrogen, the environmental estrogen bisphenol A, and selective estrogen receptor modulators (SERM). So what happened? Well, estrogen, the environmental estrogen bisphenol, and SERM reduced the replication of the flu virus in the nasal cells. However, this was only observed in women and not men, according to the report in American Journal of Physiology Lung Cellular and Molecular Physiology.

• The MD Magazine Influenza condition center

“What makes our study unique is two-fold. First, we conducted our study using primary cells directly isolated from patients, allowing us to directly identify the sex-specific effect of estrogens,” lead investigator Sabra Klein, PhD, of Johns Hopkins University, said in a news release. “Second, this is the first study to identify the estrogen receptor responsible for the antiviral effects of estrogens, bringing us closer to understanding the mechanisms mediating this conserved antiviral effect of estrogens.”

The research also revealed that the estrogens used estrogen receptor beta (protein structures that induce cell responses when molecules bind to them) to unleash their antiviral effects. This isn’t the first time that estrogen has shown its antiviral properties. Klein said that previous studies highlighted its benefits against the human immunodeficiency virus (HIV), Ebola, and hepatitis viruses.

Estrogen levels cycle in premenopausal women, therefore, the benefits are more difficult to track in the general population. However, premenopausal women on birth control and post-menopausal women on hormone replacement have more regulation so they could be better protected from the flu.

“We see clinical potential in the finding that therapeutic estrogens that are used for treating infertility and menopause may also protect against the flu,” Klein concluded.

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