Scientists Find Biological Clues on Why Women Generally Outlive Men

Sharon Moore May 16, 2013

In most countries, developed or underdeveloped, women outlive men, by average of 5.3 years. The reason for this, according to Japanese researchers, is that the immune system of men age faster than that of women.

Our immune system plays a vital role in our health. Poor immunity exposes the body to foreign substances and toxic compounds that trigger the onset of disease, such as cancer. Normally, the immune system is weak during infancy and early childhood, gets stronger in adolescence through adulthood, and declines in old age.

Biological Basis of Why Women Live Longer than Men

Published in the Immunity & Ageing journal, a study headed by Tokyo Medical and Dental University analysed the blood samples taken from 356 healthy men and women, ages between 20 and 90. They measured the levels of white blood cells and cytokines – components that interact with cells in the immune system to regulate the body’s response to disease.

As expected, the number of white blood cells in both men and women went down as they increased in age. However, looking closer, the researchers found that the rate of decline in T-cells which fight infection, and B-cells which secrete antibodies, is faster in men than in women. As the body’s defences weaken over time, the vulnerability of men’s immunity also increases. The team, led by Prof Katsuiku Hirokawa, also found that two specific types of immune system cells, the CD4 T-cells and natural killers cells, increased in number with age but the rate is higher in women than in men.

"Our findings indicate that the slower rate of decline in these immunological parameters in women than that in man is consistent with the fact that women live longer than do men." said Prof Hirokawa. He added that immunological parameters could give clues a person’s true biological age.

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Biological clue to why women live longer than men