Scientists have found a way to reverse the ageing process, extending the lifespan of mice by 20 per cent and raising the prospect of an anti-ageing treatment for humans within a decade.

The discovery has attracted the attention of NASA, which is keen to protect its Mars mission astronauts from accelerated ageing caused by exposure to cosmic radiation when they travel to the red planet in the 2030s.

David Sinclair, of the University of New South Wales and Harvard Medical School, said it was the closest scientists had come to developing a safe and effective anti-ageing drug, potentially as early as 2020.

"The cells of the old mice [in the study] were indistinguishable from the young mice after just one week of treatment," said Professor Sinclair, lead author of the research paper, outlining the findings in the journal Science.

But it's not just Mars-bound astronauts who stand to benefit. The results could lead to treatments for people who have been exposed to radiation on Earth, be they survivors of childhood and adult cancers or frequent flyers. During a flight from Australia to London, for example, travellers are exposed to the same amount of radiation as in a chest X-ray.

Radiation exposure speeds up the ageing process, compromising a cell's ability to repair damaged DNA. Even without radiation exposure, the capacity of cells to repair damaged DNA diminishes with age.

UNSW molecular biologist Lindsay Wu said the breakthrough in this research was identifying the molecular process behind DNA repair and then successfully intervening to reverse it.

This was done by giving mice water containing a booster called NMN, which is easily absorbed by cells. It is a naturally occurring vitamin and a precursor to NAD+, one of the most abundant vitamins in the body.

After the mice drank the water containing the NMN vitamin, they were able to repair damaged DNA – essentially reversing the ageing process.

"It turns out that [the level of] this naturally occurring vitamin in the body goes down with old age," Dr Wu said.

In addition to measuring the lifespans of mice, the team also gauged the animals' red blood cell count. After the mice were exposed to the same amount of radiation a cancer patient would experience during treatment, their red blood cell levels dropped. But when the mice were given the NMN booster, their red blood cell count was restored.

Dr Wu said that, as with mice, humans could expect to live 20 per cent longer under the treatment, with the additional years likely to be less burdened by disease.

"It's not just about living longer; it's about being in better health in old age," he said.

The Australian researchers from UNSW were part of an international team, including scientists from the US, Canada and Germany. NASA will co-fund some of the research after Professor Sinclair and Dr Wu's "Liberty Biosecurity" entry won NASA's iTech competition in December.

Phase-one human trials involving 25 healthy volunteers will begin in America in June to test the safety of the treatment. Future human trials will test the efficacy and dosage.

Dr Wu said the discovery also had the potential to treat female infertility. However, it was likely that the research would focus first on developing a treatment for the numerous chemotherapy side effects.

Childhood cancer survivors have a 96 per cent chance of developing a chronic illness by age 45, including Alzheimer's, type 2 diabetes and cardiovascular disease. There is also significant risk of developing secondary cancer unrelated to the original cancer.

"It would be great to do something about that and we believe we can," Dr Wu said. 

Professor Sinclair and Dr Wu have biotech companies, MetroBiotech NSW and MetroBiotech International, which are developing NMN into a drug substance.