I visited £100k per week clinic and £2k scan revealed I needed this 40p supplement

Masseuse Joanne has dispensed an invigorating one-hour treatment; my private chef Konstantina is rustling up duck on a nourishing bed of beetroot, lime and parsley; and soon my chauffeur Edin - who has driven two million miles for heads of state and diplomats - will bring the Bentley around for my £250 spa evening at the Dolder Grand, one of the world's most luxurious spas and voted frequently as the best in Switzerland.

Welcome to the world of the super-rich; a lifestyle I've been invited to share for 72 hours, as a guest of the £100,000-a-week Paracelsus Recovery clinic in Zurich.

This Swiss therapeutic facility is the ultimate international de-stress/detox location for royalty, celebrities, heads of state, stressed out CEOs and, increasingly, the fabled "founder's sons" - the scions of billionaire families whose fathers made it very big indeed, and who have themselves grown up as a consequence with every conceivable luxury... as well as every temptation, along with the gold cards to bankroll those vices.

"Imagine you've grown up in fabulous wealth with everything provided for you, but with largely absent parents," explains Jan Gerber, the 44-year-old founder of Paracelsus Recovery.

"Finding a sense of purpose can be a very real challenge, and addiction can become a very real issue. We call this 'Succession syndrome' and it can lead to a hedonistic treadmill where more is never enough."

A maximum of three clients can be treated at the exclusive, uber-discreet facility at any one time. Their schedules are carefully coordinated to ensure that they never meet during their stays, which can last a fortnight to six months, but average six weeks.

"If word got out that a CEO is undergoing immersive treatment here, it could wipe millions off their company's share price in an instant," explains Jan.

"The majority of guests are here with mental health crises, either because they recognise that they have hit rock bottom or because their company's board - or their parents - have insisted upon their attendance."

Some referrals even happen mid-flight. Private jets have diverted to Zurich airport and its VIP service when a mental health crisis takes hold in mid-air. Clients, never "patients", are supported by up to 60 staff and each stay in one of the clinic's three open-plan apartments in a grand lakeside block, with dreamy views over Lake Zurich.

One of these residences, complete with grand piano, will be my home for the next three days; a luxurious 1,800-square-feet space - the size of an average four-bedroom house - and a 30-second walk from the neighbouring clinic.

A week before arrival, I am required to complete a detailed questionnaire about my preferences, including how firm or soft I like my mattress and pillow, my favoured room temperature, and even my room scent preference. This is clearly going to be a tough journalistic assignment.

Having been collected from the airport in a £300,000 Bentley Flying Spur, 12 altar candles in a floor candelabra herald my arrival. I find lavish hand-tied flower arrangements the size of fire hydrants and every beauty aid known to man. Bed linen is changed daily. For the scion of a royal family or the son of a founder, all these attractive details would have felt little more than reassuringly familiar - and that's the idea. Jan stresses that this is generally a step down in the world for the majority of the clinic's clients.

"This is basic for them, but it mimics the luxury they are used to, and that's the important thing. They don't have the stress of trying to adjust to a different standard of living.

"So, they feel comfortable, and that enables treatment to start right away and to be effective," he explains, outlining how he fastidiously considers each detail of their living arrangements himself. He leaves the treatment plans to the world-leading clinicians he employs, including some who also work as advisers to governments on health-related matters.

One in two of the clinic's clients are dealing with addiction issues and choose to come to Switzerland - a destination long trusted for its confidential approach to private matters - from the United States, where communal 12-step addiction programs, such as Alcoholics Anonymous, would be nothing short of "traumatising" to this demographic.

"Due to their rarified backgrounds, these guests are simply not used to opening up in a group setting," says the clinic's lead psychiatrist, Dr Thilo Beck.

"But behind their success and status, they need what we all crave - love and recognition. For many of our clients, it is simply the endorsement that their feelings are OK and make sense that they need. Many people have never had that."

As my housekeeper, Cornelia Zimmermann, shows me around, it emerges that this is actually a two-room apartment. When real guests are in residence, it would contain a live-in therapist on permanent standby. "You could wake them at 3am to watch a movie with you if you needed that," she explains.

However, the live-in counsellor also holds the keys to the apartment, saving guests from the temptations of Zurich, including the casinos. And after treatment is complete, it is fairly commonplace for them to return home with their client, to help them reintegrate into their normal lives for a period of time. Intriguingly, Dr Beck, who trained at the Swiss psychiatric hospital where the pioneering psychiatrist Carl Jung used to work, was invited by Jan to work in the clinic alongside his regular role looking after the homeless.

And he says there are "big similarities" in the emotional struggles faced by the super-rich and the disenfranchised poor, so he has deep compassion for both. "They are isolated at opposite ends of the spectrum; but there is surprising overlap in the issues that they face," he says. "Both groups feel judged and out of society, with a sense of having no natural place in the world."

The eminently likeable Jan, who has a non-treatment role, is the son of a psychiatrist and a nurse clinician.

When he was growing up, his parents had a friend who needed individualised help from both disciplines, and who was invited into his childhood home for a time. This experience, and the effectiveness of the personalised treatment that it enabled, gave Jan the seeds of his idea for the business which he refers to as "pragmatic humanism".

So just how does he find his clients and encourage engagement, given the high-end fees charged? His answer reveals everything about why the service exists. "These super-rich families all have a family manager, and we are in touch with those offices," he says simply.

It's usually the family manager who will notice a problem and alert the parents as to the need to take action."Frequently, the parents are very hands-off, so they rely on information from their family office."

His business model may be niche, but it is in increasing demand. Since he founded the clinic in 2012, around 500 clients have graced its grounds and it is generally almost at full occupancy, although urgent referrals can generally be seen at short notice.

As for me, my three-day treatment stay focuses on a mid-life wellbeing assessment, an MOT for the human body that includes an armada of physical tests, including a 3D ECG, to reveal my biological age. It is a longevity and wellbeing package that the clinic also offers to those investing in their future health. A month after returning home, I receive the final results. Epigenetic tests of my blood - a £2,000 service that the clinic outsources to an American lab - show that my biological age, based on DNA testing, has revealed that I am fully a decade younger than my actual age.

But the most useful insight I receive is the discovery, while in Switzerland and strapped to diagnostic equipment for 24 hours, that despite drinking copious amounts of tea every day, I am dehydrated and my kidneys are permanently irritated due to the tannin in my favoured PG Tips, which affects the uptake of water at a cellular level.

Not a problem now, in my mid-50s, but I'm assured that this is a window into my future. To remove the risk factors, I am handed a pack of zero-sugar, vitamin-enriched hydration tablets called Waterdrop - 40p each and available on Amazon - and I make the switch from too much tea to enduring health.

One month on and I'm now guzzling up to two litres of Waterdrop-infused water every day - and far fewer cups of tea. After all, when a £100,000-a-week clinic gives you an early warning signal that is going to cost you less than £10 a week to rectify, you'd be mad not to heed their advice, wouldn't you?

• To find out more about the clinic, visitparacelsus-recovery.care