Which countries have the longest life expectancy and why?

A major new study has determined which countries around the world have the longest life expectancy.

Researchers from the University of Southern California and Pennsylvania State University in the US found that there were many determiners that prolonged the life of citizens of particular countries.

They used national life tables from the World Health Organization's (WHO) Human Mortality Database between 1990 and 2019 for men and women in these countries, with detailed information on deaths by sex, age, and cause of death.

The research found that Australians are outliving people from Britain – meaning a move to the other side of the world could extend the life of average Briton.

In the study, published in the journal BMJ Open, researchers compared Australia with five high-income English-speaking countries including the UK, Ireland, the United States, Canada and New Zealand. It concluded that Australia is the “clear best performer” when it comes to life expectancy at birth.

They found that, in 2018, baby girls in Australia could expect to live for up to four years longer than their peers in the other countries studied. Baby boys may live for almost five years longer.

The academics said Australia has a four-to five-year life expectancy advantage over the USA and a one- to 2.5-year advantage over Canada, New Zealand, Ireland and the UK.

Researchers found that people living in Monaco had the longest life expectancy in the world. Woman in the country live to an average age of 89, while men live to an average age of 84.

In second place, women in South Korea live to an average age of 87, with men living until 81. Women in Hong Kong, which sits in third place on the list, live to 87, while men live until an average age of 81.

See below for the differences in life expectancy by country:

What determines longer life expectancy?

There are many factors that determine the health and mortality of each nation, the researchers state. These can include things like levels of education and marital status.

The study suggests that women who are married have an increase life expectancy – which again increases for those with university degrees.

Men who have never been married have a lower life expectancy – even for those who are highly educated. But the authors concluded that those with the lowest life expectancies are people with “multiple social determinants that are associated with worse health”.

Researchers also found that women living longer than men can be explained in part by “different behaviours when it comes to health risk and healthcare”. They wrote than women are more likely to seek healthcare than men and have fewer health-risk behaviours, such as smoking and drinking.

According to the Royal Geographical Society, countries with high life expectancy are also usually higher income countries with access to clean water and sanitation.

Social factors such as access to and use of healthcare, as well as income and diet. The typical British diet is not considered healthy, with experts warning last year that ultra-processed foods (UPFs) account for more than half the calories eaten by the average British person.

According to insurance providers SunLife, the country with the healthiest diet is Japan, followed by Greece and then Italy.

According to the Pennsylvania State study, women in Japan live to an average age of 87, with men living until 81. They are fifth in the world in terms of life expectancy.

Possible explanations for Australia topping the list of high-income English-speaking countries is that nearly 30% of those living there are people born overseas, according to the study. Researchers state that a low prevalence of smoking and pubic health initiatives over mental health and a highly-rated healthcare system are possible factors.

They state: “Overall, Australia offers a potential model for lower-performing Anglophone countries, such as the USA and UK, to follow to reduce both premature mortality and inequalities in life expectancy.”