VietNamNet Bridge - Economists and journalists are skeptical about the numbers on Vietnam’s social and economic indicators. Few people pay attention to a number that is also very important – the average height of Vietnamese people.

The project to elevate the average height of Vietnamese people was approved in 2013 with a budget of VND6 trillion (nearly $286 million).

It aims to increase the average height of young men to 167cm and 156cm for women by 2020. This goal is set based on the current average heights of Vietnamese men and women, the growth in height of Vietnamese the last ten years, and assumptions about the influence of genetic factors.

However, there are three things that should be discussed related to this project: the current height, the possibility of the targets, and the influence of heredity.

How tall are the Vietnamese at present?

The numbers on the average height of the Vietnamese released by relevant authorities are different.

According to the National Institute of Nutrition, the average height of Vietnamese men is 164.4cm and it is 154.8cm for women.

However, the project said that the average height of Vietnamese young men is 163.7cm and it is 153cm for young women.

A survey conducted in HCM City and Hanoi in 2012, with the participation of over 1,200 showed that the average height of Vietnamese men is 170cm and 156cm for women. But these figures may not be accurate for the entire Vietnamese people because the heights of the city's residents are often higher than the rural people from 1cm to 2cm.

However, the survey figures show that in Ho Chi Minh City and Hanoi, the height of young people has reached the target of the project.

Is the project feasible?

The project aims to raise the height of young men by 3.3cm and 3cm for young women in seven years. The target figures are set based on the assessment in the neighboring countries such as Thailand and China, where every ten years, the average height increased by more than 2cm.

But in fact, no country could reach such a growth in height. A research work in Thailand, with over 86,100 people in the change in height from 1940 to 1990 showed that the height of men and women increased from 0.2cm to 1.2cm per decade.

A study in China showed that in three decades, the height of teenagers increased only 5.3cm in the urban and 5cm in the rural areas, or about 1.7cm in ten years.

In Japan, a recent overview by Dr. Tim Cole, who specializes in the study of height, showed that in 40 years (1950-1990), the height of young Japanese rose by 4cm.

Another research in Japan in 1900 - 2000 showed that on average, every ten years, the height of Japanese increased by 1.3 cm for men and 1.1 cm for women.

A study named Fels Study in the US revealed that after 50 years, the height of American increased by 4.8cm.

In the Netherlands, within 17 years, the average height rose by about 2cm for men and 2.3 cm for women.

Thus, no nation had their people’s height increase by over 2cm within ten years. The objective of Vietnam’s project, therefore, is too optimistic and ambitious.

The trap of average number

The problem is not the average height, but the difference of average numbers. For example, let’s imagine the following simple two groups: group 1 has two individuals with the height of 166cm and 168cm – and the average height is 167cm. group 2 has two individuals with the height of 145cm and 189cm – and the average height is also 167cm. Obviously, the "quality of development” of the first group is higher because the height is more evenly. This simple example shows that even if the targets are achieved, it does not mean that by 2020 the height of all young men will be 167cm and 156cm for all women.

In fact, the height of the individuals in a population is different. The differences between individuals can be measured by an index called the standard deviation.

Research on the Vietnamese people shows that the standard deviation is approximately 6cm in height. If the average height of all young men in Vietnam in 2020 is 167, with a standard deviation of 6cm, it can be estimated that up to 12 percent of young men are less than 160cm - a relatively low height . Similarly, if the average height of all young women will achieve the goal of 156cm, about 16 percent of women are still less than 150cm by 2020.

Therefore, the matter of the targets on height is not the average number but the minimum height.

It is needed to determine the minimum height to be achieved, and how many percentage of the population can reach the minimum target.

The next issue is what is the minimum threshold? To answer this question we need to have studies on the correlation between height and health, thereby determining the minimum threshold for optimal health.

Another target should be set is the age for achieving the maximum height. According to medical books, the age to achieve maximum height can range from 12-30.

Previous research works show that about 50 percent of individuals reach a maximum height at the age of 13-16, and about 40 percent of individuals reach a maximum height after the age of 16. Therefore, the criteria to be set should be the percentage of young people achieving the maximum height at the age of 13-16.

Influence of heredity factors is not only 20 percent

The project and some professionals stated that genetic factors affect only about 20 percent of the height but that figure is too low compared to reality.

Research works on the influence of genetic factors in height have been made since the 19th century. Most studies indicated that genetic factors have a great influence on the height, and range from 60-80 percent or higher.

The simplest and most effective way to see how genetic factors influence the height is through research on twins. A study of 12,000 twins in the world revealed that genes influence 80 percent or 90 percent of the growth in height.

In summary, the above data show that the currently average height of the population in a few large cities may have achieved goals set for 2020. But if the height of Vietnamese youth reported by the project is true and accurate, the 3.3cm target through fitness and nutrition within seven years is hardly feasible because the influence of genetic factors to height can reach 80-90 percent.

In fact, the height of a nation increases following economic development. When the economy develops, income is stable and increases, people will have conditions to improve nutrition and the height will increase gradually. That's the trend in Vietnam in recent times.

SGTT