Women live longer than men partly due to their immune systems ageing more slowly, according to a new study.
The study conducted in Japan suggests that men become increasingly susceptible to disease and other inflammatory conditions as white blood cells decrease faster than those of the opposite sex.
Women have an average life expectancy of 82 years compared to 79 years for men in the UK, according to the World Health Organisation.
The scientists wrote in the online journal Immunity & Ageing: "Age-related changes in various immunological parameters differ between men and women.
"Our findings indicate that the slower rate of decline in these immunological parameters in women than that in men is consistent with the fact that women live longer than do men."