It’s well-known that women live longer than men’in Canada, the average life expectancy for a woman is 83; for a man, it’s 79. Researchers have discovered one possible reason: Women’s immune systems age more slowly than men’s. Japanese researchers studied 162 healthy male and 194 healthy female volunteers, ranging in age from 20 to 90 years old. They analyzed the participants’ blood, and found that T cells and B cells declined at a slower rate in women than men. The T cells play a central role in immune-system function, while our B cells produce antibodies. The study was published in a 2013 issue of the journal Immunity & Ageing.