Monday 4 June 2007 8:00pm - 8:30pm on ITV1.

As fertility rates plummet among British males, a unique Tonight experiment discovers if 100 days on a special diet can help a team of footballers increase their chances of becoming fathers.

‘At the end of the day, Brian, scoring is all about count, motility and morphology…’

Experts believe that over the last 50 years male fertility has been in freefall. One in six couples is now believed to suffer from problems at some stage in their lives.

Everyday stresses, pollutants, diet, drink and working environment could all be affecting men’s ability to reproduce. One expert tells Tonight that evidence shows the quality of the average UK male’s semen is poor in comparison with those of some of his European counterparts.

So with the future of this island race at stake, Tonight puts the great British sperm to the test in a unique experiment.

A group of pub team footballers languishing at the bottom of an amateur Portsmouth Sunday league bravely agree to be analysed to determine whether their diet and lifestyles are affecting their fertility. They will discover if simple improvements could boost their chances of hitting the target and avert the need for potentially invasive, emotionally-demanding and expensive procedures such as IVF.

The lads range from early 20s to mid-thirties and their diets differ markedly from their professional counterparts with binge drinking and junk food common features for many of them.

After first donating a sample for analysis, the team will be asked to stick to a new, fertility-enhancing diet devised by expert Zita West for the next 100 days, spanning the growth cycle of their sperm. They will be encouraged to ditch the burgers and lager in exchange for more healthy fare such as fruit, nuts, seeds, green vegetables and filtered water.

A qualified midwife and nutritionist, Zita is a pioneer in the field of natural fertility having built a reputation for helping couples get pregnant when everything else has failed.

She says: “I am seeing more and more men coming to my clinic and sperm quality seems to be in freefall, but it is reversible and with a few easy lifestyle changes a man can increase his fertility ten fold.”

But will the team be equal to the challenge set by her?

Some are deeply concerned about their chances of conceiving, but for others the prospect of becoming a father is too far off to worry them.