Healthcare (Commonwealth Union) – The focus on what has a greater impact on disease when comparing genetic, environmental and dietary factors has long been a debate many scientists have had. The low birth rates across the world have been attributed to economic factors and impacts on fertility, hence the need to determine what exactly is impacting fertility in the food we eat and the air we breathe have been an issue scientists have attempted to tackle even more in recent times.
A recent study suggests that lifestyle choices may amplify the impact of genetic factors linked to male infertility, potentially explaining why men with comparable genetic mutations can experience very different degrees of fertility problems.
Researchers Dr. Jessica Dunleavy and Professor Moira O’Bryan of the School of BioSciences at the University of Melbourne carried out the proof-of-concept study, which was published in Human Reproduction. The researchers employed mice that have abnormalities in the M1AP gene, which are known to be a reasonably prevalent hereditary cause of male infertility in humans. However, the effects of these mutations can vary considerably between individuals.
To investigate whether environmental factors could influence the severity of the genetic defect, the researchers fed the mice a Western-style diet containing high levels of fat and sugar.
The findings showed that the M1AP genetic alteration and the unhealthy diet each had a negative effect on fertility when considered separately. However, mice exposed to both factors experienced a significantly greater decline in fertility than those subjected to either the genetic or dietary factor alone.
Notably, mice subjected to both the genetic alteration and the dietary stressor had fewer offspring, while their sperm showed poorer quality compared with animals that experienced only the genetic or dietary factor.
According to the researchers, this proof-of-principle study suggests that certain cases of male infertility could arise from the combined effects of genetic susceptibility and environmental or lifestyle influences, rather than from either factor independently. In some individuals, the interaction between these factors could reduce fertility below the level required for successful natural conception.
Variants, or mutations, in the M1AP gene are recognised as one of the more established genetic contributors to male infertility. However, their effects can vary considerably between individuals.
Men with harmful M1AP variants can experience a broad range of fertility problems, from severely reduced sperm production to azoospermia, in which no sperm are detected. Although the biological reasons behind this variation remain unclear, the findings offer a possible explanation.
Dr Dunleavy pointed out that their findings indicate that environmental and lifestyle influences, including diet, could play a role in determining how severely the condition manifests.
She indicated that even though genetics may establish a lower baseline of fertility and a predisposition to infertility, lifestyle factors could possibly have an impact on how severe the infertility is, and ultimately the ability of a male to have children. Dr Dunleavy further indicated that if correct, they predict that enhancing diet or atmospheric exposures could possibly enhance fertility.
The scientists have indicated that comparable effects may also take place with other genes that are linked to male infertility.
However, they emphasise that the findings are based on experiments in mice, meaning additional studies will be necessary to establish whether the same genetic and lifestyle interactions are present in humans.
The findings offer a valuable starting point for future investigations into the ways lifestyle factors may influence infertility. They could also help researchers determine whether targeted lifestyle changes or other interventions might improve reproductive outcomes for men who have a genetic predisposition to infertility.
Professor O’Bryan, who also serves as Dean of Science indicated that their results demonstrate why it is important to examine genetic and lifestyle influences together when seeking to understand the underlying causes of male infertility.
“Ultimately, understanding these interactions will support a more personalised approach to fertility care in the future.”
