According to United Nations world data, women live on average 4.5 years longer than men. In Singapore, women can expect to live four years longer than men. So what makes women the clear winners in terms of life expectancy?

One major physiological factor is that women suffer less oxidative stress, says Dr Kaysar Mamun​, Senior Consultant at the Department of Geriatric Medicine, Singapore General Hospital (SGH), a member of the SingHealth group.

Oxidative stress generates free radicals. “Some scientists believe that free radicals can lead to cell damage, which is one of the underlying mechanism of ageing,” explains Dr Mamun.

Oxidative damage is four times higher in men than women, possibly due to lower oestrogen levels,” says Dr Mamun.

The female hormone oestrogen has other protective effects. Oestrogen raises good cholesterol (HDL) and lowers bad cholesterol levels, thus reducing the women’s risk of developing stroke and heart disease – and dying in the prime of their lives.

Conversely, the male hormone testosterone raises bad cholesterol (LDL) and reduces good cholesterol (HDL), exposing men to a higher risk of getting stroke or heart disease at a younger age than women.

The gender gap in life expectancy however, closes up in later life.

From around age 50, women’s risk of getting stroke and heart disease slowly catches up with men because of the drop in oestrogen levels that occurs after menopause.

Impact of testosterone on male life expectancy

During puberty, men are three times more likely to die than women, mainly due to reckless and aggressive behaviour which may be associated with higher testosterone production, says Dr Mamun. Testosterone peaks during adolescence and early adulthood, and starts falling after age 30.

Between age 15 and 24, when testosterone production peaks, there is also a sudden surge in male mortality. Most common causes of male death in this age group include road traffic accidents, violence and drowning.

Extra X chromosome helps women live longer

Another biological reason for women’s longer life expectancy lies in their extra X chromosome.

While men have one X and one Y chromosome, women have two X chromosomes. The X chromosome contains microRNAs that are important in regulating the body’s immune system.

Since women have two X chromosomes, even if there is genetic mutation in one X chromosome, they have a backup copy to compensate. Men do not have this benefit. Any genetic mutations in the X chromosome in males can seriously impair their immunity against sex-linked disorders such as haemophilia and muscular dystrophy.

Physiologically, the one last advantage women hold over men is their better ability to fight infections. “Women tend to experience fewer bacterial and viral infections than men during their lifetime,” says Dr Mamun.

Lifestyle factors help women live longer

Men tend to be more competitive and engage in more risky behaviours which may lead to higher stress levels and mortality, adds Dr Mamun. Men are also more likely to take high risk jobs which may contribute to early demise.

Higher rates of smoking and alcohol consumption expose men, particularly those in their 40s, to a high risk of getting stroke, hypertension and heart disease.

In terms of eating patterns, men generally prefer red meat and tend to eat less vegetables and dietary fibre. These eating habits have been linked to high cholesterol, heart disease and even cancer.

A study by the Harvard School of Public Health showed that eating just one serving of unprocessed red meat daily could increase one’s risk of premature dying by 13 per cent. Red meat consumption also increases one’s risk of dying from heart disease by 18 per cent and cancer by 16 per cent.

So should men resign to shorter life expectancy?

The good news is the gender gap in life expectancy has shrunk in recent years. “By taking proactive steps in reducing the risk factors for life-threatening illnesses, men can expect to live longer. Simple changes in lifestyle and dietary habits can also boost male life expectancy,” says Dr Mamun.

Ref: T12