Stem cell injections could hold the secret to eternal youth as tests showed that they tripled the lifespan of laboratory mice.

Scientists believe that with further research stem cells could also halt the ageing process in humans by giving them a "shot of youthful vigour".

Researchers from the University of Pittsburgh studied mice that had been genetically engineered with the premature ageing condition progeria. They found that after being injected with stem cells they grew bigger and stronger and were able to live three times as long as their younger, healthier counterparts.

The 17-day-old, rapidly ageing mice saw an increase in their lifespans from an average of 21 to 28 days to more than 66 days after the injections. They also showed improved muscle strength and brain blood flow.

The researchers also looked at the effect of stem cells in a lab dish where young stem cells were placed next to prematurely ageing cells. The performance of the sick, ageing cells visibly improved when the healthy cells were placed next to them.

The findings were published today in the journal Nature Communications.

Study author Dr Laura Niedernhofer said: "Mice that got a shot of stem cells just before showing the first signs of ageing were more like normal mice and grew almost as large."

She added: "The young stem cells seem to secrete something that is quite beneficial. Just what it is, we’re not entirely sure."

The researchers hope that the by discovering what that is, the technique could be used to extend the lives of humans.

Niedernhofer said: "The beauty of them is we can take them out of muscle and expand them so we have a useful therapeutic population of cells."

She added: "If all of us could be treated with our own cells, we could eliminate problems with rejection and immunity."

Research continues into the possibility of injecting the ageing cells of humans with young stem cells in a bid to reverse the ageing process. In the meantime, do your bit to stay young and healthy with our round-up of the best anti-ageing herbs...

• Anti-Ageing Herbs That Protect Against Premature Ageing

• Milk Thistle

  Milk thistle encourages the liver to make a powerful antioxidant, which aids the regeneration of new skin cells and helps to create a glowing, youthful complexion.

• Ginseng

  Ginseng is a perennial herb and its root is used to help beat age-related problems such as high blood sugar and cholesterol levels. It also helps alleviate stress, stimulates physical and mental activity, which may slack in older age, and protects the body from severe, physical pain.

• Rhodiola Rosea

  The Rhodiola Rosea is an 'adaptogen' herb which has long been used to enhance the body's ability to cope with mental stress. It is also believed that the herb could help protect the brain from age-related mental disorders such as Alzheimer's and enhance body stamina and strength.

• Rosemary

  Rosemary helps to redress the skin's moisture balance, perfect for fending off sagging and wrinkles. It also helps protect the skin cells from environmental damage by aiding the development of collagen in the skin, leaving it plumper and more supple.

• Ashwagandha

  Ashwagandha is thought to help with the prevention of dementia by restoring the neurotransmitters in the brain. Ashwagandha also helps the body build a resistance to stressand can be used as stimulant for a healthy immune system.

• Ginkgo Biloba

  Gingko Biloba contains crucial antioxidants that help to improve blood flow to the brain which help the body's peripheries function - ideal for those with poor circulation in the fingers and toes.

• Cat's Claw

  Also known as Uña de Gato in Spanish and Vilcacora in Indian, the Cat's Claw herb's super-immune-system qualities help battle age-related problems such as high blood pressure, bad circulation and high cholesterol levels.

• Grape Seeds

  The seeds from the grape contain powerful antioxidants called procyanidins that neutralise damaging free radical in the joints.

• Pine Bark

  Pine bark, also known as Pycnogenol, strengthens capillaries, arteries and veins and fights inflammation to improve joint flexibility. It also helps the body to circulate more blood during stressful conditions without increasing blood pressure or making the heart work harder.

• Reishi

  Known as the 'mushroom of immortality' this colourful fungi has been a folk medicine in China for thousands of years. It is traditionally used to treat age-related conditions like hypertension, arthritis, insomnia and lung disorders. It is also a great anti-inflammatory agent and can be taken in the form of tea or tablets.