The research, led by scientists from Imperial College London and using data from most countries in the world, tracked height among young adult men and women between 1914 and 2014.
Among the findings, published in the journal eLife, the research revealed South Korean women and Iranian men have shown the biggest increases in height over the past 100 years. Iranian men have increased by an average of 16.5cm, and South Korean women by 20.2cm.
The height of men and women in the UK has increased by around 11cm over the past century. By comparison, the height of men and women in the USA has increased by 6cm and 5cm, while the height of Chinese men and women has increased by around 11cm and 10cm.
The research also revealed the once-tall USA had declined from third tallest men and fourth tallest women in the world in 1914 to 37th and 42nd place respectively in 2014. Overall, the top ten tallest nations in 2014 for men and women were dominated by European countries and featured no English-speaking nation. UK women improved from 57th to 38th place over a century, while men had improved slightly from 36th to 31st place.
The researchers also found that some countries have stopped growing over the past 30 to 40 years, despite showing initial increases in the beginning of the century of study. The USA was one of the first high-income countries to plateau, and other countries that have seen similar patterns include the UK, Finland, and Japan. By contrast, Spain and Italy and many countries in Latin America and East Asia are still increasing in height.
Furthermore, some countries, particularly those in sub-Saharan Africa, North Africa and the Middle East have even seen a decline in average height over the past 30 to 40 years.