Until recently, when a couple were trying for a baby, the focus was mainly on the importance of maternal health. Now, there is increasing evidence that a father’s health at the time of conception also has an impact on the future wellbeing of any offspring.
At The Florey Institute of Neuroscience and Mental Health in Melbourne, researchers have shown for the first time that a father’s gut health plays a role in this. Previous work has revealed that offspring are affected by changes in their father’s sperm caused by bacterial infections and viruses, as well as diet, exercise and stress.
“It’s largely in the last couple of decades that we’ve discovered all this,” says the institute’s Professor Anthony Hannan. “We’re used to hearing that women need to look after their physical health for the sake of their baby. Our discoveries in mice, and emerging findings in humans, suggest it’s important that men do so, too.”
For the latest study, male mice were given a cocktail of oral antibiotics to deplete their gut microbiome – the ecosystem o-f microbes that live in the digestive tract. This resulted in epigenetic changes to sperm that had repercussions for their offspring. Both male and female children had reduced body weight and gut length. And the females also showed increased anxiety and depressive-like behaviours.
This is a complex area, with each study showing different effects on the sperm and the offspring, and there is a lot that scientists still don’t understand. But there is evidence that strands of non-coding RNA (molecules essential to biological functioning) can be passed on via sperm affecting gene expression – basically turning genes “on” and “off” and influencing the way an organism develops and functions.
“It seems that almost everything a father is exposed to, in terms of lifestyle factors and also environmental exposures, has the potential to alter sperm,” says Hannan. “How does the information delivered by the sperm into the egg change embryonic development? And how does that affect the foetus, the baby, the child, then the adult offspring? We’re really just at the beginning, pioneering a whole new field here.”
The theory is there may be evolutionary reasons for these epigenetic changes to sperm. For instance, if a father was stressed because there was a sabre-toothed tiger stalking outside the cave he could, through his sperm, make his offspring more anxious and risk-averse so they stayed safer.
Most of us no longer live like the hunter gatherers we evolved to be and the concern is that modern lifestyles could be causing alterations to sperm that will prime future generations for a range of mental and physical health problems.
“Over a couple of hundred years, humans have radically changed our environment,” says Hannah. “Now, we have an environment that encourages sedentary behaviour and is filled with junk food. It’s psychologically stressful, decreases sleep and, in some cases, reduces cognitive stimulation.
“These things affect the whole body, including the sperm cells that funnel information into the egg and so can affect any aspect of the offspring, not just brain development but metabolism, endocrinology, physiology. The incidence of depression, anxiety, autism and schizophrenia could go up. You may be looking at a next generation more predisposed to overweightness and obesity. Will they be more predisposed to diabetes, heart disease, to cancer?”
While science is doing the work to find out, there is plenty that men can be getting on with to give their children the best chance of good health. A man’s body is constantly creating new sperm. It takes about 50-60 days for it to develop in the testicles, and around 14 days more to fully mature. That creates an opportunity to overhaul lifestyle and improve sperm quality.
Epigenetic changes aren’t necessarily permanent. One study, from the University of Copenhagen, identified changes in the sperm of obese men that were linked to behaviours that included eating patterns and appetite. When the men underwent bariatric surgery to help them lose weight, their sperm epigenetics, including non-coding RNA, started moving back towards normal.
“We all know what we need to be healthy,” says Hannan. “We should be physically active like our hunter gatherer ancestors. We shouldn’t be eating junk food. We need to control stress, sleep properly. Some men might not be prepared to do that for themselves, but if they’re wanting to become a father, would they do it for their children?”
