Men may have a weaker immune system and could be more vulnerable to so-called 'man flu', scientists propose.
Evolutionary factors and hormonal differences may make males more susceptible to infection than females, says a Cambridge University team.
Their theory, outlined in a scientific journal, suggests there is a trade-off between a strong immune system and reproductive success. But a leading flu expert says there is no difference in men's immunity.
Previous experiments have found differences in the ability of females and males to deal with infection. Across a range of animal species, males tend to be the 'weaker sex' in terms of immune defences, says the Cambridge team. This is usually explained by the difference in hormones.
High testosterone levels, they say, lead to more coughs and colds.