London, Jun 26 (IANS): Men who grew up in challenging conditions like prevalence of infectious diseases or poor nutrition may have lower levels of testosterone -- male sex hormone -- in later life, says a study.

The findings suggest that the differences may be linked to energy investment. For instance, in environments where people are more exposed to disease or poor nutrition, developing males direct their energy towards survival at the cost of testosterone.

While high testosterone levels may up the risk of ageing, muscle mass, prostate enlargement and cancer, lower levels may cause lack of energy, erectile dysfunction etc. Thus, the researchers suggest that any screening for risk profiles may need to take a man's childhood environment into account.

"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," said Gillian Bentley from Britain's Durham University.

For the study, published in the journal Nature Ecology and Evolution, the team collected data from 359 men born and still resident in Bangladesh; Bangladeshi men who moved to London as children; Bangladeshi men who moved to London as adults; second-generation, Britain born men whose parents were Bangladeshi migrants; and Britain born ethnic Europeans.

The results showed that Bangladeshi men who grew up and lived as adults in Britain had significantly higher levels of testosterone compared to relatively well-off men who grew up and lived in Bangladesh as adults.

Bangladeshis in Britain also reached puberty at a younger age and were taller than men who lived in Bangladesh throughout their childhood.

Further, it was also found that the aspects of male reproductive function remain changeable up to the age of 19 and are more flexible in early rather than late childhood, but no longer heavily influenced by their surroundings.