The key for women living much longer than men lies in their immune system. According to a new study, the immune system in women remains healthy for long, and this ability to fight off infections helps them live longer.
On average, women live at least six to eight years longer than men. By age 85, there are about six women for every four men. Experts have believed that women develop healthy habits at a younger age, which help them live longer. A recent study had found that a set of DNA inherited from the mother accelerates the process of aging in men.
In the present study, researchers have found that the immune system in women ages slower than that of men, which helps them live longer.
The study was conducted on a group of participants whose ages ranged from 20 and 90 years. Researchers found that in both men and women, the number of white blood cells decreased with an increase in age.
White blood cells are also called leukocytes, and help in fighting infections. There are five types of white blood cells - basophils, Eosinophils, lymphocytes (T cells and B cells), monocytes and neutrophils.
The number of neutrophils in both men and women decreased, the study found. The number of lymphocytes increased in women and decreased in men; however, the number of lymphocytes is actually higher in young men, and so with age, the number of these cells becomes comparable in both genders.
Further, the T cells and B cells had a slower rate of decline in women than men. Decrease in the number of red blood cells was also faster in men than women.
"The process of aging is different for men and women for many reasons. Women have more oestrogen than men which seems to protect them from cardiovascular disease until menopause. Sex hormones also affect the immune system, especially certain types of lymphocytes. Because people age at different rates a person's immunological parameters could be used to provide an indication of their true biological age," professor Katsuiku Hirokawa from the Tokyo Medical & Dental University Open Laboratory said in a news release.
The study is published in the journal Immunity & Ageing.