overweight and obese men had sperm with less motility

New research carried out in Sao Paulo, Brazil shows the importance of being slim to boost male fertility. The study shows that when men have extra body fat they can damage their sperm and are at the greater risk of passing on a genetic defect. The good news however is that the negative effects of obesity appear to be reversible and therefore men who lose weight can significantly improve the chances of producing a child.

Dr Ricardo Bertolla, who headed this research, explained that there were a number of theories as to why obesity has an effect on the genetic structure of sperm. One of the theories is the obesity causes oxidative stress which can affect the sperm’s genetic patterns and another is that the extra fat which forms around the scrotal area increases the temperature of the sperm, thus damaging it. The final theory is that because obesity has a direct impact on the regulation of male hormones it is possible that as an ongoing result the sperm is also affected.

The research which involved over 300 men included detailed studies of the DNA, mitochondria and motility of sperm samples from all of them.  Dr Bertolla noted that both overweight and obese men had sperm with less motility; they also noted that both of these groups also had less mitochondrial activity but only the men who were classified as obese actually suffered from DNA fragmentation.

Mitochondria which can be described as the energy boosters in cells are essential to sperm because they give them the ability to fertilise the female egg. Sperm containing fragmented DNA patterns could lead to embryos with a whole list of inherited illnesses.

Dr Bertolla whose research was presented at the American Society for Reproductive Medicine which was held in Atlanta, USA said that at present he did not see any evidence to show that the negative effect of obesity on sperm health was irreversible but he did recommend that men with fertility problems went on a diet.