Scientists have finally found out why men recover from flu quicker than women
We all know someone who has come down with a case of 'man flu,' or we have even come under its effects ourselves. It usually involves some cold symptoms including a sore throat, sneezing, fatigue, a constant stream of complaints and a fair amount of eye-rolling from surrounding women.
However, while it's easy to poke fun at, there is some science as to why men and women react differently to the same infections - and it's not all down to men feeling looking for extra sympathy.
Last year, a study that took place at the Memorial University of Newfoundland in Canada found that men have a less robust immune system, suggesting that it may be testosterone that's to blame. “Men may not be exaggerating symptoms but have weaker immune responses to viral respiratory viruses, leading to greater morbidity and mortality than seen in women,” Dr Kyle Sue, a clinical assistant professor at the university, wrote in the BMJ.
A weaker immune system may have some evolutionary benefits, as energy is invested in other biological processes - such as "growth, secondary sex characteristics, and reproduction". Beyond this, there may also be a scientific reason why men recover at a faster rate than women, after a study took place to investigate the effects that influenza can have on male and female mice.
Researchers from Johns Hopkins Bloomberg School of Public Health published the study in Biology of Sex Differences. Discovering that women tend to suffer more seriously from the flu than men, they sought answers by infecting live mice and human cells extracted from male humans with H1N1, a strain of Influenza A. This strain is also known as “swine flu”, which caused a global flu pandemic in 2009 and 2010, but they used a non-lethal dose.
It turned out that when infected, the male mice and human cells produced more amphiregulin - a growth factor that plays a role in tissue repair and development. An increased production of amphiregulin is believed to lead to a faster recovery time from the flu. To corroborate these claims, male mice who produced less of the growth factor had similar recovery times to female mice.
“The novel finding here is that females also have slower tissue-repair during recovery, due to a relatively low production of amphiregulin,” said lead author Sabra Klein, an associate professor at Bloomberg School.
There is a possible link between influenza recovery time and the production of amphiregulin, but the study did not determine why men are more likely to produce higher levels of this growth factor than women are. One possible explanation could be the higher levels of testosterone in men - suggesting the sex hormone could have significant effects on our immune system.
The good news is that future flue treatments could seek to boost the production of amphiregulin, a treatment that would be especially beneficial for women.