I am not the only one for whom many of life's most intimate details come flooding back at the sight, smell and taste of particular foods. Everyone I speak to seems to have a favourite or, in some cases, a most hated dish with which they can recall particular moments of their lives.

In many cases the taste or smell of a sweet, a cake or an entire meal is capable of painting a picture with richer, deeper brush strokes than any snapshot in their photograph album. It is curious that, while I struggle to remember my mobile phone number or grapple helplessly to recall the closest of friends' names when I am required to introduce them to someone, the merest sniff of chocolate ice cream has been known to bring back memories from 20, 30, 40 years ago with frightening clarity. Put that same ice cream on a little wooden spoon and I can recall the cinema I was in when I ate it, the feel of the (red) velvet seats on the back of my bare knees, the colour of the ice-cream attendant's overall (lemon, with green piping). Details more glowing than if I had eaten that ice cream two hours ago.

In his bestselling book Fever Pitch, Nick Hornby tells his life story through the football matches he has been to. While my own personal madeleine was not so much Arsenal's victory against Tottenham as the sensation of pulling a tooth out while chewing a Bluebird milk chocolate-covered toffee, it is true to say that memory triggers are as varied as the lives of those who seek to evoke them. Memories of food and the part which certain crumbs play in people's lives fascinates me. It satisfies both my incessant nosiness and acute greed. So much so that I have just spent several weeks talking with everyone from Alan Bennett to Vanessa Redgrave for a television series about the dishes through which they could tell the story of their lives.

I wrote Toast partly to unravel the emotional mess that was my own childhood, unwrapping humbugs and licking ice-lollies in order to relive something that happened a lifetime ago. My legs are still stinging from the slapping my Dad gave them when I spilt raspberry juice on the new dove grey carpet; the scent of violet cashews brings back fond memories of the soft, black leather handbag belonging to a favourite if somewhat pungent aunt; the tiniest sniff of a barley sugar awakens the horror of a good hiding I once got for hunting through my mother's bag (mushroom, to match her shoes) in search of her gold tin of 'travel' sweets. The whiff of Robinson's Barley Water reminds me wincingly of once pissing my pants.

Curiously, although the flavour of beetroot in vinegar might still instantly transport me to the back lawn of 67 Sandringham Road, Wolverhampton on a summer's day in 1965, it is actually what hits the nose - sweet, earthy, acidic - rather than the tongue that really hits the mark. In terms of total immersion in a time long gone the nostrils seem to win over either the eyes or the taste buds. When people say tomatoes don't taste like they used to they may be commenting on the changes in commercial production of the fruit (the variety, the soil, the modern chemicals) or simply on their own taste buds' inability to experience a flavour the way they used to. Yet I would argue that it is the aroma from the freshly snapped stalk of a home-grown tomato that is more likely to whisk them off to Dad's old greenhouse than putting one in their mouth.

I can reveal that Richard E Grant sniffs almost everything he eats. A legacy from a childhood in Swaziland where he checked the fish on his plate was fresh; Janet Street Porter hates the smell of stewed lamb because of the vision of her mother that appears at the first twitch of her nostrils; Vanessa Redgrave adores the comforting scent of a proper cooked breakfast. The nose can act as our own personal Google, searching out essential facts from the mass of information that goes to make up our lives.

It isn't all rose-tinted nostalgia. Victims on BBC1's Crimewatch often mention their attacker's smell. The whiff of their clothing, breath or hands becomes inseparably linked with the trauma of the incident. A smell can reveal vital clues because it can open up pieces of your brain that remain closed by the horror of it all. Despite finding eggs exquisitely beautiful to look at, the smell of their sulphurous yolks unwillingly brings back painful images of my father's weekly force-feeding sessions. One sniff and I start to heave. Such moments are the opposite end of the spectrum from the aroma of ozone and vinegar that is so effective a tool for summoning up an ideal fish and chips on the pier in Brighton. It doesn't mean they are any less powerful.

Of course, food linked with memorable events is more likely to kick off a few reminiscences than something we eat every week, which is why we probably remember birthdays more clearly than the average Sunday lunch. Even so it was nothing more than a mundane pickled herring that whisked me back to St Ives on a magic-carpet ride of onion, dill and vinegar the other day. And not only just to St Ives, but to the car park where my young niece slammed her fingers in the car door. Sharp flavours that brought back every tearful moment of a painful event. Having had many a herring since that dark day, it was only this one, with its distinctive piercing whiff of dill and white vinegar, that opened that particular box. And how one particular mango out of the hundreds whose juices dribble down my chin each year, was the one that reminded me of a woman I once met in a hotel in Sri Lanka. A crazy woman, who played opera at full blast from the bedroom of her hotel in the early hours of the morning - and yet someone I had completely forgotten about till every line in her face came back to me with one bite of that absurdly juicy fruit. And what exactly was it about that mouthful of boiled potato that reminded me of my school history teacher?

Of all the food triggers that can pop up in our lives there are a few that have done it for me more than others. Treacle tart makes me think of a mysterious uncle, gammon and parsley sauce is unmistakably linked to a row with my stepmother, grilled kippers to an Edinburgh bed and breakfast where I tossed my bacon into a plant pot in the dining room, eggs mayonnaise of being sacked from a job in a hotel, cucumber soup conjures up one of the happiest days of my life, a bowl of chocolate tapioca (don't even go there), and a certain recipe for fish soup with fresh coriander that allows me to relive a dirty weekend in Paris blow by blow. Recipes that all spark deeply detailed recall of not just where I was and whom I was with, but of details so bright and sharp they could have happened yesterday; to tell the truth, probably a damn slight clearer.

· A Taste of My Life is on BBC1, at 11.30am Saturdays