Indians growing taller, but fall short in world order

NEW DELHI: The average Indian is taller than his/her parents, but that's not saying much. Between 1914 and 2014, the average height of Indian men increased by about 3cm to reach 165cm (5'5") while women grew taller by 5cm to become 153cm (5'1"). This leaves our men about 17.5cm shorter than the world's tallest males in the Netherlands, while Latvian women, the world's tallest, tower above our women by 17cm.

These findings emerge from a massive study of human height measurements involving 1,470 earlier studies covering over 18.6 million participants in 200 countries. The study was conducted by more than 800 researchers and led by scientists from Imperial College, London.

Most countries have shown an increase in height over the past century, with Iranian men and South Korean women shooting up most-by 16.5cm and 20.2cm. But the once-tall Americans-placed third among men and fourth among women in 1914-slipped to 37th and 42nd place in 2014. Overall, the ten tallest nations in 2014 were dominated by European countries, and featured no English-speaking nation.

Why have some nations shot up while others have not? Environmental factors are important in determining average heights of populations, James Bentham of Imperial College told TOI.

"Factors such as good nutrition, clean water supply, avoidance of childhood infections, and a mother's health during pregnancy affect how much these children grow. We believe that the relatively small gains in height in India are likely to be due to some or all of these factors," he said.

In India, the nutrition board under National Institute of Nutrition (NIN) measured the height of Indian rural men and women at regular intervals between 1975-79 and 2011-12. There was a marginal increase of 1.2cm among men and only 1cm among women, study co-author Dr A Laxmaiah of NIN told TOI. The heights of earlier years were estimated from these records.

Although low height gains in India reflect poor nutritional levels and high disease prevalence, children today are much taller than their parents were at the same age. This has been revealed in studies by Harshpal Singh Sachdev, senior pediatrician at Sitaram Bhartia Institute, comparing children with their parents. "Our data shows that children aged between 5 and 13 years are on average 5.5cm to 7.5cm taller than their parents at the same age 30 years ago.

Obviously, they are still in a growing phase and the difference will increase. These changes are comparable to or greater than those seen in developed countries at a similar stage of socio-economic development about 50 years ago," he said.

How much role does heredity play? Sachdev says that there are 200 genes associated with height but their net contribution in determining adult height is about 10%.

"Though genetic factors play an important role in determining height at individual level, environmental factors such as income, age-specific balanced diet, sanitation, health facilities may exploit genetic potential," said Laxmaiah. Confirming this, Bentham said that if all populations across the world lived in the same environment, it's likely there would be some differences in mean height between certain populations, but we would not see the 20-23cm gap between the tallest and shortest countries witnessed at present.