Testosterone Levels May Be Determined in Childhood
In this study have been compared salivary testosterone levels, height, weight, and age at puberty onset in Bangladeshi men raised in various environments: middle-class residents in Bangladesh (107 men); Bangladeshi men who migrated to the UK as children (59 men); adult immigrants to the UK (75 men); and UK-born children of Bangladeshi migrants (56 men). The researchers assumed the men would share some dietary and lifestyle habits. Europeans born in the UK (62 men) from the same neighbourhoods and socioeconomic class were also studied for comparison.
Study results showed that Bangladeshis born in the UK and child migrants arriving by age 8 (before puberty) had significantly higher levels of testosterone compared with life-long residents of Bangladesh. UK-born Bangladeshis were younger at puberty and grew taller than Bangladesh residents. In addition, they had higher waking testosterone levels than Europeans born in the UK. The European men did not have significantly higher salivary testosterone levels than any of the groups.
A man's absolute levels of testosterone are unlikely to relate to their ethnicity or where they live as adults but instead reflect their surroundings when they were children. Bangladesh presents more ecologic risks than the UK, including higher exposure to infectious diseases and worse health care, the investigators noted. Men raised in Bangladesh probably spent more energy fighting off infection than producing testosterone. By adulthood, men's testosterone levels appeared far less influenced by their surroundings.
Very high and very low testosterone levels can have implications for men's health and it could be important to know more about men's childhood circumstances to build a fuller picture of their risk factors for certain conditions or diseases.
Magid K, Chatterton RT, Uddin Ahamed F, and Bentley GR. Childhood ecology influences salivary testosterone, pubertal age and stature of Bangladeshi UK migrant men. Nat Ecol Evol.DOI: 10.1038/s41559-018-0567-6