Scientists say that people who are aged 55 or so, should start taking the protein powder favoured by body builders to add almost 10 years to their life.
Dissolved in water, the mixture built muscle, boosted fitness and improved balance and co-ordination.
Tantalizingly, the powder, which can be bought from health food shops and online, increased life expectancy by 12 per cent.
The amazing results come from animal experiments, but, in human terms, this would equate to an extra 10 years or so of life.
The Italian researchers believe that taken daily from middle-age, the 'elixir of life' powder could help millions look forward to a healthier old age.
Sprinkled on porridge or stirred into milk, it could strengthen weak and worn worn-out muscle, cutting the risk of painful falls and fractures in old age.
Taken in later life, the supplement could give a much-needed energy boost to those with heart, lung and other problems.
"I think our data warrant a recommendation that middle-aged people start taking these supplements," the Daily Mail quoted researcher Enzo Nisoli as saying.
In addition, the powder, which contains twice as much leucine as isoleucine or valine, does not have any side-effects, said the professor.
Although it is not clear if the supplement, which is already used by body builders and sold under brand names including Aminotrofic, would extend human life, Nisoli believes it could have clear health benefits.
Taken from the age of 55 or so, the protein powder could boost the odds of a healthy old age.
Those who start on it later in life might find that it helps with cardiac problems such as heart failure, and lung problems, and with diabetes.
However, the animal experiments suggest it would be of little or no benefit if taken when young and healthy.
The supplement is one of many potential anti-ageing potions and powders being researched around the world.