Swiss scientists claim they are one step closer to unlocking the elixir of life because a new clinical trial has shown the secret to reversing the ageing process is hidden inside pomegranates and raspberries.

A new study revealed that human clinical trials found naturally occurring Urolithin A (UA) stimulated genes that reverse the loss of muscle through age. The compound, which is created in our bodies as we digest the fruits, has extended the lifespan of worms and mice in previous studies.

Study author Professor Johan Auwerx, of the École Polytechnique Fédérale (EPFL) in Lausanne, Switzerland, said: "These latest findings, which build on previous preclinical trials, really crystallise how UA could be a game-changer for human health."

UA is a natural metabolite derived from digesting plants that has been shown to boost muscle health in old animals and human-ageing models. Its rejuvenating properties have shown further promise after Prof Auwerx carried its first ever clinical trial on humans - and found it had no negative side effects.

Some 60 elderly people in good health but with a sedentary lifestyle were given a single or multiple doses of synthesised UA over a four-week period. In the first round of tests, researchers gave some participants a single oral dose of UA, between 250 and 2,000 mg.

They carried out the four-week test after confirming there were no negative side effects when compared to a control group. Participants were split into groups given a daily oral dose of either 250 mg, 500 mg, 1,000 mg of UA and a control group which received a placebo.

The team found that at doses of 500 and 1,000 mg, the gene expression of mitochondria in skeletal muscle cells was affected. Mitochondria were stimulated to create more muscle cells in the same way exercise does.

As reported on scotsman.com¸ the study has been published in the journal Nature metabolism and an EPFL spin-off called Amazentis is planning to bring UA products to market as quickly as possible.