If you type the term “human growth hormone” into the search engine Google you will find more than 5 million entries including paid adverts from web sites around the world touting it as a miracle cure for all the ills of ageing.

This hormone is credited as an elixir of youth with the ability to turn fat into muscle, rejuvenate sagging skin, restoring libido and reversing memory loss.

The majority of these sites are promising eternal youth by selling bottles of water containing vitamins and amino acids and many are labelled “homeopathic” Hgh. But the truth is the real stuff is made synthetically by just a few pharmaceutical companies and the only way to take it is by injection and it is available only on prescription.

The use of Hgh as a rejuvenation treatment is the subject of much controversy amongst the medical profession since it’s only manufactured for the treatment of growth deficiencies in children and severe adult deficiency – not for ageing. There have been no long-term studies of it as a rejuvenation treatment and the possible side effects which might include carpal tunnel syndrome, diabetes, bone loss and even cancer.

But this hasn’t stopped its popularity as a rejuvenation treatment in the expensive clinics of Beverly Hills and New York and London. Doctors prescribe the treatment which costs about $40,000 (£20,000, €30,000) each year to their rich and celebrity clients in the form of a convenient injector pen.

According to the US magazine, the National Enquirer, devotees of Hgh, include Hollywood celebrities such as Nick Nolte, Pam Anderson, Janet Jackson, Madonna, Demi Moore, Brad Pitt, Marla Maples, Britney Spears and Jennifer Aniston.

The popularity of hgH followed an experiment in the US in 1990 in which a group of 12 men aged over 60 years saw dramatic changes in their bodies as signs of ageing melted away. In the Rudman Study, named after Dr Daniel Rudman, fat turned to lean muscle, bone density increased, skin became thicker and the men looked generally dramatically younger. Their sex drive also increased. They were monitored for adverse effects but there were none.

Produced by the pituitary gland, Hgh is responsible for growth in childhood and helps the metabolism of carbohydrate and fat. It peaks in adolescence but by the time a person hits 60 years the body’s production will have fallen by 50% or more. It is produced naturally at night and also stimulated by exercise.

In medical rejuvenation programmes the doctor will usually prescribe it alongside other anti-ageing hormones to restore levels to that of a younger person. These hormones include melatonin, testosterone, oestrogen and the so-called “performancing enhancing” steroid used by athletes, DHEA (dehydroepiandrosterone).

The Belgian endocrinologist Dr Thierry Hertoghe who promotes the benefits of Hgh at anti-ageing conferences and takes it himself says that without the hormone’s benefit, “we would all be tiny little dwarfs that are shy, anti-social, weak and tired,”

Hertoghe who is the author of “The Hormone Solution – Stay younger longer with natural hormone and nutrition therapies” believes that current hormone replacement therapy which consists of replacing only one or two hormones is outmoded and that the body’s 100 hormones must function in complex harmony.

Problems occur as we age because hormones inevitably diminish, disrupting the balance, which may trigger weight gain, fatigue, wrinkles, and hair loss. Fortunately, a regimen of natural hormones can protect us, according to Hertoghe, and his book offers anecdotal evidence of dramatic transformations. Although he includes self-scoring checklists so you can determine your own hormone profile, he wisely urges you to implement your own “hormone solution” by working closely with your doctor. .

“In less than six months, a woman of 60 can have legs of a 35- to 40-year-old,” he says.

Hertoghe has treated hundreds of elderly patients whom he has given human growth hormone injections. By restoring Hgh levels typical of a twenty-or thirty-year-old, Hertoghe claims to have thickened their thinning hair, erased their deep wrinkles, lifted their sagging eyelids, smoothed their puffy eyes, toned their sagging muscles, and tightened the loose skin on their cheeks and under their chins. “It’s like magic,” he says.

In the UK the debate was reignited recently when one doctor admitted that he and his wife had both rejuvenated themselves with Hgh, But in London’s Harley Street you will find very few doctors who will admit to prescribing this drug even though they are allowed to go what is called “off-label” if they feel it is justified in the interests of a patient.

One doctor who has used the treatment on herself is Dr Cecilia Tregear. She says that when she reached the age of 50, she was overweight with a BMI (Body Mass Index) of 29 to 30 and looked older than her years and tired. So she embarked on multiple hormone replacement therapy after testing her own blood for deficiencies.

After two years of treatment she says she was transformed by her treatment which included a course of bio-identical hormones.

‘My BMI was down to 23 and I was full of energy,’ she says. ‘The wrinkles had vanished from my skin. My brain worked much better and there was no sign of osteoporosis,’ says Dr Tregear

But the Hgh debate rumbles on. A review of 31 studies involving 200 patients, led by researchers at Stanford University in the US, recently concluded that the benefits of human growth hormone therapy are insignificant compared to the increased risk of many conditions including joint swelling and pain, carpal tunnel syndrome, diabetes and prediabetes.

They found that the only benefit associated with its use is slightly increased lean body mass. The therapy increased 2 kilograms of muscle mass and reduced 2kg of fat in the study subjects.

But says Dr Ronald Klatz, president of the American Academy of Anti-Aging Medicine (A4M) said “Thousand sof published studies on hundreds of thousands of patients have demonstrated the clear benefits of adult growth hormone replacement therapy, when utilized under proper clinical guidelines and at proper physiological dosages.

“To deny the benefit of HGH and other essential hormonal regulators of metabolism in deficient patients based on age may be considered a heinous act of malpractice which will prove to be erroneous and shortsighted in the years to come.”

ELIXIR’s own fitness expert, Jon Trevor, say: “Most people would be better off exercising more often and taking vitamin supplements. Injecting with Hgh is not only expensive but there appears to be no credible results to back it up. In the same way that the supplement creatine was all the range for body builders, the introduction of yet another stimulant should be treated with caution.

“Hollywood for the here and now is so image driven that I feel that the long term health effects are cast aside, no doubt the doctors that are prescribing Hgh have their clients sign some form of a disclaimer and so the era of the quick fix is upon us. But this may not turn out to be a quick fix years down the line.”