A nutrient found in a 'tomato pill' could supercharge sperm by up to 70% and offer new hope to couples who are struggling to conceive, scientists believe.
The compound lycopene, which gives tomatoes their red colour, is now the focus of a study at Sheffield University.
Researchers hope to measure how male fertility is affected by an over-the-counter modified lycopene supplement, which is known to double blood lycopene levels.
The Sheffield team led by Professor Allan Pacey, one of Britain's leading experts on male factor infertility, is recruiting 60 healthy male students and university staff aged 18-30 years old to take part in the three-month study.
It comes as one in six couples revealed they are unable to conceive. It is believed that a lot of the time this is due to men having poor quality sperm.
During the study, half of the group will receive twice-daily capsules of the over-the-counter supplement called XY Pro, and the other half will receive identical dummy capsules.
Professor Pacey said: "Studies elsewhere in the world have shown that the antioxidant properties of lycopene seem to have a beneficial effect on sperm quality and we want to investigate this further.
"Production of sperm takes three months. This study will tell us if lycopene improves the quality of sperm already in development by reducing DNA damage, and whether it produces an overall increase in the number of mature sperm.
"There is enough evidence out there to indicate this study is worth doing and I am cautiously optimistic.
"If it works in the volunteers we would then consider testing it in infertile patients."
The group will provide sperm and blood samples at the start of the project to establish baseline sperm quality and lycopene levels.
They will give two further sets of blood and sperm samples halfway through the study and at the end to see how much the XY Pro has boosted their sperm.
Neither the researchers nor the volunteers will know who got the XY Pro and who got the dummy capsules until after the trial has ended to prevent them trying to influence the results.
A recently published study by fertility specialists at America's prestigious Cleveland Clinic in Ohio, showed lycopene can boost sperm quality by 70%.
Professor Pacey said a number of other studies have also indicated that lycopene can slow down the progression of prostate cancer, and the enlargement of the prostate that causes bladder problems in older men.
He added: "We know lycopene seems to have a beneficial effect on the health of the male reproductive system and I'm cautiously optimistic our trial will show a benefit for sperm production.
"If it is the next step will be to offer the treatment to men with fertility problems."
Professor Roger Kirby, a London specialist in men's reproductive health, said he has recommended the use of lycopene for a long time.
He said: "I have been prescribing for it for many years, and I would welcome more trials to measure the benefit and prove how it works."
Lycopene is one of the fastest growing health supplements. Other studies have shown it also benefits heart function and may slow the progress of other types of cancer.
Nigel Iskander, spokesman for Cambridge Nutraceuticals, the Cambridge University spin-off which manufactures XY Pro, said the company is working with a number of other universities around the world to prove the value of lycopene supplementation.
He added: "We know this compound is very beneficial and we are anxious to garner as much scientific evidence as possible for its use."