Madrid: Scientists at the Spanish National Cancer Centre found evidence that a natural protein could be the key ingredient in an elixir of eternal youth.

According to the scientists, boosting the amount of the naturally forming substance, telomerase, in the body could prevent cells from dying and thereby slow the process of ageing.

Telomerase helps maintain the protective caps at ends of chromosomes which act like ends of shoelaces and stop them unravelling. As people age and the cells divide, these caps become frayed and shorter and are so damaged that the cell dies eventually.

So far the scientists have only carried out an experiment on laboratory rodents. They found that those mice genetically engineered to produce ten times the normal levels of telomerase lived 50 per cent longer than normal. Those animals also had less fat, had better co-ordination and were better at processing sugar.

Lead researcher Maria Blasco said that the enzyme was capable of turning “a normal, mortal cell into an immortal cell” and a similar approach could eventually lead to extended human lifespans.

“You can delay the ageing of mice and increase their lifespan. (But) I think it is very hard to extrapolate data from mouse ageing to human ageing,” she told the New Scientist magazine.

One of the problems with boosting telomerase is that it can increase the risk of cancer. However, she said that the obstacle could be overcome by issuing cancer drugs that could offset the negative affects.