As I exit the train I join an unbroken stream of people running from the platform, across the road and round the corner to the main entrance of the Olympia exhibition centre: men and women (mostly women) with tight ponytails and sensible shoes, many with rolled-up mats under their arms. I had been prepared for the Mind Body Soul Experience to be many things, except wildly popular. I suppose I should not have been surprised – it is meant to be the largest trade show of its kind, encompassing all manner of complementary therapies, spiritual awareness and personal development.

Once I’m inside, it becomes clear that a lot of people are here for the yoga. The Om Yoga show is happening in the cavernous National hall, while the Mind Body Soul Experience is up some stairs in an adjacent exhibition space. The two shows are in some sense separate, although for ticketing purposes they are as one.

In any case, there appears to be a bit of overlap: stalls selling copper insoles and magnetic healing dog collars are down here next to the ones promoting yoga clothes, yoga mats and yoga holidays. I’ve got nothing against yoga. I tried it once, after someone told me it would bring me joy. I liked the sound of that. I remember walking into the yoga studio thinking: as soon as I get my joy, everyone else can go to hell. But all I got was very, very sweaty. Yoga, I realised, was actually just exercise.

The copper insole, on the other hand, belongs to a branch of human understanding people sometimes call Wellness. I must declare a certain bias here: I don’t believe in Wellness. I struggle to keep an open mind when I encounter a stall sponsored by the Federation of Subtle Energy Medicine. It is a table piled with pretty coloured crystals. I ask the man what the difference between them is.

“Well, the carnelian, for example,” he says, picking up a shiny red chunk. “People tend to find that quite grounding.”

“Uh huh,” I say.

“Red has a longer wavelength,” he says. “That’s actually scientific.”

“Can I take one of these?” I say, picking up a leaflet. This is my way of declaring an intention to move on. Within minutes, I have an armful of paperwork.

The National hall harbours a queasy mix of straightforward selling, old-fashioned hucksterism and out-and-out mumbo jumbo. There are men hawking posh blenders. I spot a clothing range called Wellicious and another called Frederick Lies Still. There is a display of scented stones not far from a stall for a company called Humidity Solutions. I imagine yoga studios probably do get quite damp, but this must be a pretty odd gig for a dehumidifier salesperson.

There are tables covered with bite-sized samples of health foods, all of which have one thing in common: they taste awful. At the four corners of the hall, yoga classes are underway; the schedules promise demonstrations of variants including Broga (for dudes), Voga and Hip-hop Yoga. There is even one called Tequila Yoga Rave. It is my understanding that they actually give you a shot of tequila at the start. It is supposed to help free you from “the tyranny of thought”. That more or less chimes with all my experiences with tequila.

As I pass one stall, a man thrusts a small box into my hand containing a “sinus rinse” starter kit.

“Take two,” he says, giving me another box.

“What’s it for?” I say. He opens a box and takes out a plastic bottle, and explains how to fill it with water and a sachet containing compounds I discover to be salt and bicarbonate of soda. He lifts the nozzle of the bottle to one nostril and mimes squeezing it.

“I’m supposed to squirt water up my nose on purpose?” I ask.

“Sounds weird,” says a woman standing next to me. It is the only note of scepticism I will encounter all afternoon.

“How can I explain?” the man asks. “In America, it’s more of a cultural thing. It’s like brushing your teeth.”

I am American, I want to tell him. This is not part of my culture.

I stop to talk to Adi Guru, a Hare Krishna who has been coming to the show every year since he started his incense import company. “I was fresh out of the ashram, just got married, needed some money,” he says, holding out a sample of sandalwood incense. “Perfect job for a Krishna.”

I realise I’m only forestalling my visit to the hardcore Mind Body Soul Experience, so I bid Adi Guru goodbye. At the top of the stairs, I see what appears to be a massage conducted without touching: the would-be masseur is rhythmically stroking the air surrounding her client. I decide to keep a corresponding distance. At the edge of the exhibition, I encounter a charming gentleman who sells portable deep-tissue massage beds. Our conversation is reassuringly straightforward.

“How much do these go for?” I ask.

“£3,675,” he says.

“Whoa,” I say.

“We sell a lot for horses,” he says. He shows me a picture of the equine model, a sort of massaging horse blanket. We look across the hall at the other exhibitors.

“It would be difficult to agree with all of it,” he says.

He’s right. Even the most open-minded alternative therapy advocate would have to accept they can’t all work. If you believe that theta healing is “the practical application of quantum mechanics” (it’s not, by the way), then you shouldn’t really also believe that consulting angels is the way forward. And yet people here seem to be combining therapies, practices, essential oils and faiths in innovative and sometimes alarming ways: yoga and magnets, angels and skincare.

To be honest, I don’t really have a problem with a combo such as “spiritual haircutting” – a “professional haircut and healing experience rolled into one”. It may sound a bit silly, but talking nonsense and doing a good haircut are by no means contradictory disciplines. The effect of one doesn’t cancel out the other. I’m much more worried by the leaflet I pick up from someone who claims to be both a Subtle Energy Medicine specialist and a qualified dentist.

As I pass the rows of hanging dreamcatchers, the stalls for psychics, natural linen and, weirdly, the RSPB, a man blocks my path and starts speaking to me about a detoxifying treatment made from a volcanic substance called clinoptilolite. He hands me samples in powder and capsule form.

“So it’s basically ground-up rocks,” I say.

“It’s one of very few products on the market that’s negatively charged,” he says.

“How does it work?” I ask, with a heavy heart.

“Do you want to start on Tim?” he asks. How does he know my name? Can he read my thoughts?

Tim, it transpires, is a display mannequin with a diagram of a digestive tract drawn on its front. When you eat the powdered rocks, the man explains as he points, it absorbs the toxins and heavy metals in your intestines.

“Can I take a leaflet?” I say.

“It’s not pseudoscience,” he says. “It’s an actual medical device. This is actually used by the German army.” He rubs the green powder on the back of my hand.

This encounter knocks something out of me, namely all my remaining curiosity. The pervasive smell of incense is beginning to give me a headache. I long to leave this giant celebration of good posture, human credulousness and the placebo effect. I try to pick my way back to the stairs without catching anyone else’s eye. I give a stall called the Jesus Experience an especially wide berth. I’m not sure how the Jesus Experience differs from the experience of regular Christianity, but I’m pretty sure I don’t want to sit down and find out.

On the way past some kind of cosmic healer in mid-consultation, I spy a big testimonial printed on the wall behind her, which I begin to transcribe: “On that moment I realised how much weight I was carrying on my shoulder due to those unshed issues. Amazing how I was ready to reface my life with more serenity.” I’m fascinated by how generic it is. It could be printed on any of the stalls, excepting perhaps the Humidity Solutions one. A small, wide-eyed young man sidles up to me.

“Come and write down what we’re saying,” he says, smiling and looking at my notepad.

“I’m not writing what she’s saying,” I tell him. “I’m just copying out the …” I turn and see his stall behind me. The sign says The Knowledge Book.

“What is it?” I ask. “Some kind of bible?” I can see one on the table: a large, red, hardcover volume. He explains that it was written in Turkey between 1981 and 1993, or rather its contents were revealed to someone over that period, who then wrote everything down. And really, it’s much more than a book.

“It’s a technological device as such,” he says. “It uses a special light proton cyclone.”

“A what?” I ask.

“You’re scanned as you read,” he says, explaining that this allows the Knowledge Book to adjust its energy intensity to the understanding level of each reader.

“That’s good,” I say, a tiny note of panic in my voice.

“It has a supervisory capacity, basically,” he says. He can’t just be mad, I think. There are two other people manning the stall with him – they must believe this stuff as well. He starts telling me about weekly seminars in the London area.

“Where do you live?” he asks.

“Can I take a leaflet?” I say.