YOU can spend a lifetime bombarded by images of Helena Christensen without knowing much about her. She's notably been quoted for saying the most important things in life are cheese and sex. Ever since, journalists have been bringing her gifts of cheese.

"Ah, thank you," she says, not in the least surprised when a truckle of Mull cheddar and some oatcakes are placed on the table in front of her. She tucks in immediately. "I only had yoghurt for breakfast," she says. "But don't worry, I can eat and talk at the same time."

So she can. Between mouthfuls she explains that obviously cheese is not like sex, although she does love cheese a lot. "You know I think they just wrote that about the cheese," says Christensen in an accent that is Nordic with hints of New York, her adopted home. "Honestly, I would never mention the word sex in an interview because I know my family would read it. No, they wouldn't be offended, but I would feel shy about it."

For someone who has inhabited the upper echelons of a profession renowned for its prima donnas, its haughtiness and naughtiness, she seems plainly grounded. But even in the age when the original supermodels stalked the earth she never had a reputation as one who wouldn't get out of bed for less than however much it was.

At 38 she still models, is a mother, co-founded a style magazine, has acted, and not just in that sexed-up Chris Isaak video. She owns an antique shop in Manhattan, does charity and environment campaigning and works as a professional photographer. She's not so much model-turned-whatever as model-turned-everything. An exhibition of her photographs is opening later upstairs in the Amsterdam hotel we are sitting in. Tonight the beautiful people of the Dutch capital will sip champagne, flirt and gossip but all evening most eyes will be on her, not her pictures.

She's quite aware of how fortunate she is to have that power and that the attraction of Helena Christensen the photographer is actually centred on Helena Christensen the supermodel. "The term supermodel is a bit funny, but if you've got to be in a business like this then you might as well be in it at this level and go all the way," she says. "It's such a strange job and so few people get their foot in the door and work with the most talented people in the business. I was around creative and inspiring personalities every day for 15 years."

She dropped out of runway modelling on the birth of her son, Mingus, seven years ago, and now she can afford to be choosy. But she's still an ubiquitous presence turning up most recently in Persil's campaign to persuade us all to turn down the temperature on our washing machines.

With a whole new generation of catwalk queens coming up, lately it's become the case that you've seen one supermodel, you've seen them all. Although they're a rare genus, Covermodelis Vogueis can be seen around London quite often at various times of year. Just two days earlier, on Portobello Road, Claudia Schiffer tottered past. Schiffer wasn't recognisable from her plumage of goldilocks tresses, but by her improbably thin arms and legs. She has that almost sparrow-like, thin body shape of a divine alien shared by others of the breed such as Kate Moss, Victoria Beckham and Liz Hurley, although Hurley, when you see her for real, looks as if she's had buttock and boob cushions sewn into her outfits.

Not so with Christensen. She looks perfectly normal, or should that be just perfect. The late Gianni Versace famously pronounced her as having the most beautiful body in the world and millions of photo shoots later, no one can take that away from her.

She arrives in the hotel restaurant all smiles, with her long, chestnut brown hair shower-wet. She's wearing a ruched black batwinged top, which looks nicer on than it's described (forgive me I'm a man), and slim black trousers. No make up, no jewellery, bar a long neck chain that plunges too deeply into her bosom to accurately report what might be on the end of it.

She's tall, an effect pronounced by straw-heeled espadrille sandals displaying toes lacquered so perfectly red that all you can think is 'you did not paint those yourself'. The immediate effect is that she is undeniably, exotically beautiful, a combination of Danish and Peruvian parentage, she says. Her physiognomy is fascinating, Nordic from a distance with the cheek bones and flat forehead, but close up and front on she has a more rounded Incan look. In a passport photo these contrasting features might fight each other, but you notice in almost every picture of her, she nods forward just before the shutter clicks or throws her chin back and to the side, consciously or unconsciously elongating her facial features, creating the look that made her a supermodel.

Encased in these exotic features are those burning green eyes with irises that don't so much follow you around the room as trail you around town for several days afterwards. They're quite astonishing, almost as amazing as her perfect skin. Officially they're green, but even in the washed-out North Sea light of the Netherlands they have an electric sparkle that lock you down. She must be used to being stared at all the time, which is the only excuse you can come up with for unavoidably staring at her all the time.

Christensen says she feels good about herself, and at an estimated net worth of £14 million you could argue who wouldn't? Such are the wages of sublime beauty. Approaching the big 4-0 she's inevitably conscious of the ageing process, but tries to make light of it. "We all change and it's a bloody shame, but this age, the way I feel now mentally and physically, is perfect for me," she says. "I never did anything before, but I've been boxing for two years, so physically I'm in better shape than I've ever been.

"My son said to me the other day, "Can you always be the way you are now?" like he always wants to be seven, and I said to him, "You have no idea how much that is a human wish." Of course I would love not to get any older. I'm not thinking about losing my youthful appearance or anything, I just don't want to die. I just want to live and live and live," she laughs.

"If a vampire came to me in the middle of the night and told me I could live forever if he bit me right now, I'd say yes, bite away. I would say yes even if I had to, oh, suck a rat. I wouldn't hesitate for a moment." She laughs again, delightfully, and I find myself wondering how much it costs to file teeth these days.

The cheese is going down well and conversation turns to food again. Christensen was a child model, from a small island not far from Copenhagen, a normal teenager and an 18-year-old Miss Denmark. Afterwards she went to Paris to pursue a modelling career. First she did Elle magazine and then a cover shoot for Vogue by Peter Lindbergh put her into the modelling stratosphere.

Coming from where she did protected her from the size zero pressure that the industry is in paroxysms over now. "Being Danish, you become very self ironic and you have a certain confidence in yourself that doesn't allow for other people to put pressure on you. That was probably a very important quality to come into the business with. No one was messing with me, that's for sure," she says. Well, no one was messing with her appetite, anyway.

"I'm telling you the most important thing for me every day of my career was, where's my next meal, how much can I eat in the half hour break? And room service, my God, room service was probably the highlight of my career. I could check in to a hotel room and order enough food for six people. They would literally wheel in the tray of food. Those were the days man. I didn't care if I was working the next day for an amazing magazine, doing the cover. That was a nice little perk, but travelling the world and eating all the food of different cultures - that was the greatest advantage of this job for me."

She used to have posters of Bono on her bedroom wall as a teenager and now her photographs of the diminutive rock demi-god adorn the exhibition space upstairs. Some of her circle of famous friends are there as are intimate family portraits. There's Michael Stipe with his trousers down, Robbie Williams being nervous and Viv Tyler looking at a tiny television. That picture was taken the day Christensen discovered she was pregnant.

"I never talk about my work in any technical terms, I don't even consider it work, they're just my pictures," she says. "For the exhibition I just chose pictures that have the same mood and feeling, the same kind of stillness to them. I think an atmosphere, a melancholic feeling."

For the record she's an old-fashioned photographer, shooting on a 5x4 camera or the sadly obsolete Polaroid 665 film stock. "They don't make it any longer - its very sad," she says. Nylon, the style magazine she co-founded gave her a platform as a photographer and having been to the best classes in the world, ie working with the best photographers in the business, she has an eye and a style.

She may be a photographer and describe herself as just a hippy girl, but at heart she's a rock chick. Since her Michael Hutchence days, which ended when she saw pictures of the late Paula Yates hanging off his arm, Christensen has been in and out of the arms of young(er) rock musicians. She spent the previous evening in Amsterdam at a gig by Bright Eyes, the indie rock vehicle for a young Nebraska born musician Conor Oberst, and he returns the compliment by accompanying her to exhibition opening.

The previous weekend she flew to Dublin for the Oxygen music festival where she was spotted with Josh Hartnett who, when he's at home, is described as "Hollywood heart-throb". A few weeks beforehand the British tabloids had her hooked up with the Coldplay bassist Guy Berryman after she'd split from Jack Hudson, an actor she was dating for a year. They are both friends of Gwyneth Paltrow and Chris Martin and, apparently, just friends themselves.

She's done long-term relationships too; she was with Norman Reedus, the father of her son for several years before they divorced, but she is now basically single. It's hard to let people in and Christensen says she doesn't want to be back in a situation where she's dependent on someone else's feelings and moods.

"It's great to be single, but I never really think of myself as being a girlfriend or a single person, I'm way too independent for that. I don't think I ever really introduced myself as being someone's girlfriend even when I was in a relationship. I guess I just don't define myself like that. I think it's because I've always been on my own and travelling so much, so I can't even say, 'This is my boyfriend,' when I introduce someone. And I've hurt for it, when someone says to me, 'Why do you never introduce me as your boyfriend?'"

Talking to her about relationships, you can see how the confusion over cheese and sex arose. "My God, you eliminate a lot of emotional stress and a lot of pressure by not opening up to relationships, but it's so great when it's there too," she says. "You know when the time is right. You know how your body will tell you, 'I want vegetables' or 'I need a big, juicy, red steak'? Your mind does that too, telling you right now that you need to be with someone, feel the closeness of someone, the warmth, the touch of someone else. Other times your mind tells you 'I'm doing my own shit right now. I'm developing as a human being'."

She splits her time between New York, where her son goes to school, and Copenhagen where he spends the long summers and winter with her parents. "I'm giving up my place in Monaco because I live full time in New York. When I was travelling, because I didn't really have a country of residence, it made sense to have a little place to relax once in a while. Now he goes to school in New York and I have a little shop there, but I still travel. Actually, I think I've been on 15 planes in the last three weeks." So much for the environment, Persil Lady.

She's just been to London finalising a deal for a hair product range she's launching with Jamelia and Erin O'Connor. It is a gilded existence, I say. "It's perfect for me because I use so much conditioner and now I can get it for free," she jokes. Her hair has dried out a bit by now. A quick check in the compact mirror, less time than some women take to compose themselves before answering the phone at home, and she's happy to pose for pictures which an hour earlier were going to be a problem.

Just as she anticipates the click of the camera, controlling the shutter with a flick of her head, it dawns on you that she has effortlessly controlled the interview too, introducing each new topic without really being prompted and subtly moving on to territory where she is comfortable. Or maybe I'm just a pushover for a pretty supermodel who likes cheese and oatcakes.

Underneath that easy-going exterior I suspect she's quite controlling, but she does it by being so spellbindingly charming that you don't notice. When she talks about love she starts a husky and harmonic rendition of a Chet Baker song. "I fall in love too easily, I fall in love too fast," she whispers just a few inches from my ear and it's like being hypnotised. Nothing in the armoury of professional aloof detachment that protects you from Earth girls can resist this. Then you know how truly bewitching her beauty is.

"That song is so beautiful," she coos. "He basically sings about how quickly he gets into someone and how hard he falls after that. As you get older you have a harder time opening up and letting it all filter in. But, you know, I'm easy man. I can say all that right now and tonight I'm in love." If, at that stage, she'd asked me to eat the proverbial rat of eternal life I would have licked my lips and stretched for the last oatcake on the table to accompany it.

But she doesn't. Instead she asks, because we've been talking about the benefits of parents having more than one language, to hear some Gaelic spoken. So, slightly tongue-tied, I compliment her on her eyes, but she's remains completely unfazed (damn, that one usually works). Then, touché, she responds with what might be a Danish sweet nothing or nothing at all. I can't understand a word she's saying, but I know I'm blushing as brightly as the nail varnish on her toes.

Helena Christensen: Selections From A Quiet Story till August 15 at Hotel Arena, Amsterdam;