Child Height Development in the Past Half Century in North East Asia: Animal Protein and Other Essential Nutrients

Economies in North-East Asia made rapid progress after WW II. Japan was the first-runner, followed by South Korea with some two-decade-lag due to the Korean War (1950-53). As the standard of living, food supply in particular, improved, children grew taller in height unprecedentedly, by more than 10cm in a half-century. Male teens in Japan were 2-3cm taller in mean height than their Korean peers in the 1960-70s but ceased to grow any taller in the early-1990s, whereas Korean teens kept growing taller vigorously, to overtake their Japanese peers by 3cm in the mid-2000s and then ceased to grow taller afterwards. Economy in South Korea has kept very prosperous toward the end of the 2010s and supply of animal-sourced foods kept increasing steadily. When growth patterns of boys’ height from 1st graders in primary school to seniors in high school examined for the two countries, velocity began to decline steadily in South Korea in the early-2000s, to be appreciably slower than their Japanese peers toward the end of the 2010s. As pre-school boys in South Korea were significantly taller than their Japanese peers in the mid-2000s, Korean teens were still taller than their Japanese peers in the end of the 2010s, but it could be predicted that the height advantage of Korean teens over their Japanese peers would not last in the future decades. Children in Japan ceased to grow taller in height in the 1990s, because they started to turn away from fruit at-home consumption a decade ago in the late-1970s. Younger cohorts in South Korea started to steer away from vegetables at their household consumption drastically in the mid-1990s. It is suspected that a drastic reduction in vegetable consumption by growing children and pregnant mothers may have resulted in slower growth in child height, as observed in South Korea since the early-2000s.


Data
In the realm of human-biology, "the first 1,000 days" are critical for determining future stature [5][6][7]. Cole and Mori, analyzing secular trends in child height in Japan and South Korea by SITAR, concluded: "most of the increment seen in adults had already accrued by age1.5 years" [8]. Japan's national nutrition surveys for example, is not large (54) to allow for quite large SD (4.7 for mean height of 117.6cm) [9]. The more comprehensive health and nutrition survey was initiated in South Korea only in the year of 1998, followed by the second one in 2001 [10].  [14,15], which will be referred, if necessary.
For the sake of international comparison, FAOSTAT should be safer for consistent, unbiased references.

A.
Less than half of female middle school graduates went into high school education before the 1980s in the Korean society.
Mean height of female high school students during the earlier years of this study are presumed to be a couple of centimeters taller, upward biases than the national averages by age groups. This study analyzes only male students for this reason.

Secular trends in hight of children in the past half century
Japanese and South Korean schoolboys will be compared in i.e., racial potentials (figure1).
The author was 165cm tall, when younger. He has two sons, both of whom are 175cm, seemingly slightly taller than their contemporaries. The author was hungry all the way from primaryschool through high school days. His sons did not eat plentiful animal-sourced foods but never experienced every day hunger. One of them has a son, college junior, 181 cm tall, who is substantially taller than his classmates, but apparently shorter than his college basketball players. He was a baseball player in junior-senior high schools, who ate much more foods, slightly more meat and   Table 1).

Changes in growth velocity in the two countries over the past few decades
Some three years ago, the author noticed that children in Korea seemed to grow much faster in their adolescence than their Japanese peers, although the data were limited, i.e., years In drawing growth curves, plotting different ages observed in the same year can barely be a close proximate, or might distort the real picture [18].   nutrients is insufficient" [19,21]. White Paper on Agriculture, 1994, Japan remarked a concern on wakamonononokudamaonbanare (steering a way from fruit by the young), without explicit implications on its outcomes [20]. Tanaka

Brief Conclusions
In the past half century, Japan and South Korea made steady economic progress, accompanied by remarkable improvements in standard of living. Teens in Japan ceased to grow taller in the end of the 1980s and teens in Korea kept growing taller to overtake their Japanese peers in mean height by 3.0cm in the mid-2000s but then also ceased to grow any taller afterwards, when the national economy still kept growing vigorously. Supply of animal protein fails to explain these failures in statue growth in the two countries.
The author discovered one thing in common in the two countries, i.e., children in growing ages started to turn away from fruit in the end of the 1970s in Japan to eat barely 10% of fruit, as compared to the older adults in the mid-1990s and likewise children in South Korea started to turn away from vegetables in the early-1990s to eat less than 10% of vegetables, as compared to those in their 50s in the mid-2010s.
It is surmised that vegetables/fruit should contain essential nutrients for child height developments. Per capita consumption/ supply, as provided by food balance sheets, FAOSTAT, or Department/ Ministry of Agriculture, individual countries, does not identify the changes in individual consumption by age groups, in the presence of cohort effects in consumption of staple food groups, such as rice, vegetables and milk [27][28][29]. Developments in human height are determined by supply of inputs to health, food supply before children reach the age of maturity. When we analyze any association between food consumption and child height development, it is advisable to identify food consumption by age groups, i.e., growth stages in stature [30][31].