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26/06/2016 - Institutional news

IMIM involved in a study of the evolution of global heights over the last 100 years

Source: Imperial College

The research, led by scientists from Imperial College London and using data from most countries around the world looks at the heights of young adult men and women from 1914 to 2014.

Height is strongly influenced by nutrition and environmental factors, although an individual's genetic factors may also play a role.

Among the findings, published in the journal eLife, the research has revealed that in South Korea and Iran, where people have shown significant height increases over the last 100 years, Iranian men are now an average of 16.5 cm taller, and South Korean women have increased their height by about 20.2 cm. The study involved the IMIM's Cardiovascular epidemiology and genetics research group that has contributed with 11,000 people from the database of the REGICOR Project and the Clinical and Molecular Epidemiology of Cancer research group

Men and women in the UK have got about 11 cm taller over the last century. In comparison, the height of men and women in the US has only increased by 6 cm and 5 cm, while for Chinese men and women the rise is also about 11 cm and 10 cm.

In addition, the researchers found that people in countries like the USA, UK, Finland and Japan have stopped getting taller over the last 30 to 40 years, despite showing initial increases at the start of the study. In contrast, the populations of Spain, Italy, and many Latin American and East Asian countries continue to increase in height. Some countries, particularly those in sub-Saharan Africa, North Africa and the Middle East have even seen a decrease in average height over the last 30 to 40 years.

Height is strongly influenced by nutrition and environmental factors, although an individual's genetic factors may also play a role. Children and adolescents who are better fed and living in better environments tend to be taller, and their height can even be influenced by the health and nutrition of their mother during pregnancy. This has permanent consequences for health, and even education and income. Some research suggests that people who are taller tend to live longer, get a better education and even earn more. Even so, being tall can pose certain health risks because studies have linked height to an increased risk of suffering certain cancers, including ovarian and prostate cancer.

Professor Majid Ezzat of Imperial College, who led the research, explains, "This study gives us a picture of a nation's health over the last century, and reveals that the average height in some nations may even be declining while in others it continues to grow. This confirms that there is an urgent need to tackle the environment and nutrition of both children and adolescents worldwide, to make sure that we are giving the world's young people the best possible start in life."

And he adds, "Our study also shows that the English-speaking world, especially the US, is falling behind other high-income nations in Europe and Asia Pacific. Along with the poor performance of these countries in terms of obesity, this emphasises the need for more effective policies dealing with healthy nutrition throughout life."

Maria De Silva, head of Population, Environment and Health at the Wellcome Trust, which co-funded the study, says: "This is a unique analysis that reveals the true power of combining populational data sources that span the globe over a century. The most surprising finding is that despite the huge increases in height observed in some countries, there is still a considerable gap between the tallest and shortest countries. More research is needed to understand the reasons for this difference and help find ways to reduce the health disparities that still persist across the globe."

The research team, which included almost 800 scientists as well as the collaboration of the World Health Organisation, used data from a wide range of sources, including information on military service, health and nutrition, population surveys, and epidemiological studies. They used this data to generate information on the height of people at 18 years of age in 1914 (born in 1896) compared with 18 year olds in 2014 (who were born in 1996).

Highlights of the team's findings include:

• Dutch men are the tallest on the planet, at an average height of 182.5 cm. Latvian women are the tallest in the world, at an average height of 170 cm.
• The four countrieswith the tallest men are the Netherlands, Belgium, Estonia and Latvia. The four countries with the tallest women are Latvia, the Netherlands, Estonia and the Czech Republic.
• Men from East Timor were the smallest in the world in 2014, at an average height of 160 cm. The women of Guatemala were the smallest in 2014,at an average height of 149 cm.
• The difference between the populations of the tallest and shortest countries in the world in 2014 was approximately 23 cm for men, an increase of 4 cm compared with 1914. For women, the height difference between the tallest and shortest countries in the world has remained the same throughout the century, at about 20 cm.
• The difference in height between men and women has remained virtually unchanged for 100 years: the average height difference was about 11 cm in 1914 and 12 cm in 2014.
• The average height of young men and women has dropped up to 5 cm over the last 40 years in certain sub-Saharan countries in Africa, including Sierra Leone, Uganda and Rwanda.
• In 2014, Australian men were the only non-EU representatives in the top 25 tallest in the world.
• In East Asia, South Korean and Chinese men and women are now taller than their Japanese counterparts.
• Adult height has stagnated in South Asian countries, such as Bangladesh and India, at around 5-10 cm lower than in East Asian countries, like Japan and South Korea .
• The shortest adult men in 1914 were found in Laos, where the average male height was 153 cm, a similar height to a well-nourished 12-year-old today. It was found that in 1914, the shortest women were Guatemalan, where the average height of women was 140 cm, similar to a well-nourished 10-year-old.

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