When someone confesses the one thing they couldn't live without is wheatgrass, you know you're in trouble.

While less saintly individuals are currently battling with New Year diet plans and attempting to not to give a piece of chocolate cake even a sideways glance, nutritionist Jacqueline Young has enviable
self-discipline.

"I'm quite evangelical about wheatgrass," she says, mixing the dark green powder with some water and pushing the mix in my direction. "If you're feeling tired or just need an energy boost, forget about caffeine, get yourself some wheatgrass."

Jackie's description of a regular intake of liquid chlorophyll as the equivalent of "drinking a meadow" is somewhat poetic, but the taste isn't entirely unpleasant and in these desperate times, desperate measures are needed.

According to statistics, one in seven over-65s are malnourished, and more than half of all secondary school pupils buy treats equivalent to 20 blocks of butter and 11 bags of sugar during the course of a year. While the celebrity chefs have made a killing out of telling us how to cook in a healthier way, too few of us are actually listening.

And then, of course, there's the North/South divide with the North somewhat predictably coming out worst. In Yorkshire and the Humber, more than 24 per cent of all men are clinically obese, less than one in five adults eats the recommended five portions of fruit or vegetables a day and in the North-East as a whole people will live the shortest, are the biggest binge drinkers and the heaviest smokers.

In light of this bleak picture, the launch of the county's first dedicated nutrition clinic in York, which will offer members of the public one-to-one consultations as well as running accredited training courses, couldn't have come at a better time.

It was a happy accident that the clinic opened its doors on the same day that the Public Library of Science Medicine claimed it was possible to increase lifespan by 14 years simply by giving up smoking, taking exercise, drinking in moderation and, crucially, eating five servings of fruit and vegetable a day.

That advice seems clear enough but with the weight of research increasing in direct proportion to the nation's waistline, some of the public have been left confused about what should and shouldn't be on the menu.

"Every day you can flick through the newspapers and turn on the radio and there are stories about the latest superfoods, the ultimate balanced diet and frightening tales of excessive salt levels in some convenience foods," says Jackie, who will oversee the new centre. "The problem is that many of the stories are conflicting and often when people don't know where to turn, they begin to rely on supplements.

"Unfortunately, that whole area is a minefield, some don't work at all and if you have a particular ailment, those that do can sometimes cause real harm.

"For example, if you're on certain blood thinning medication and are also taking vitamin E it can cause it to thin even more and that's potentially very dangerous.

"Everyone can benefit from having a nutrition assessment. The idea you are what you eat has been around for such a long time, but more people are now accepting that it's actually true. Once people would only come to us as a last resort, but more and more are coming to us as a first choice."

It seems the seeds of the current problem were sown at least partly in the 1970s when Soda Streams were a sign of the upwardly mobile and Angel Delight became an easy alternative to home-cooked puddings.

"When I first started, the vast majority of people who came to see me were suffering from digestive problems, but now it's everything from migraines to joint problems," says Jackie. "We are in the midst of the convenient food hangover. In the 1970s, parents still cooked healthy meals for their children and things like chocolate biscuits were regarded as a treat.

"For some people, the treats have become their staple diet, they don't know how to cook and even if they did, they wouldn't know what to do with a fresh vegetable.

"Food books by celebrity chefs may sell by their millions, but most of them end up gathering dust."

The new York centre is housed in the city's existing Northern College of Acupuncture and while complementary therapy has often had an uneasy relationship with the traditional medicine, the nutrition industry has become increasingly regulated in recent years and Jackie is more than prepared to stand by her results.

"So many mothers come to me with their teenage daughters who are suffering chronic period pains and so often it's because they are not getting enough essential fatty acids," she says by way of example. "The desire to be skinny means they have often cut out things like dairy products and lots of red meat, but they are also missing out on vital vitamins and mineral which help the hormonal process.

"Sometimes it's as simple as getting them to snack on seed or cereal bars instead of chocolate and, honestly, normally within three cycles the problem can be cured. Those kind of things I get quite evangelical about."

Recent stories, from the Suffolk teenager who suffers from a condition which means she is only able to eat chips to the 12-year-old boy allergic to everything but chicken, tuna, carrots and potatoes, have shown there is no one-size fits all approach to solving the nation's dietary woes and often it's the most innocuous foodstuffs which cause the biggest problems.

"One of my clients was a successful lawyer in the City, who had suffered from chronic indigestion for 20 years," says Jackie, who also runs a practice in London. "Most of the time he tried to ignore it, but part of his job was regularly dining out with clients and as the years went on the problem worsened, so much so he would often have to excuse himself from the table to vomit.

"We did a series of tests which showed he was intolerant to, among other things, green beans and peppers, the kind of food he was eating every day.

"By eliminating them from his diet and taking a combination of digestive enzymes to help breakdown the food and essential fatty acids, three weeks later all the symptoms had gone."

For every success story there will always be some less heartening tale, from the mothers in Rotherham who delivered junk food to their children in protest at a school's menu change to the dinnerlady in York who received a series of abusive phonecalls after coming out in support of Jamie Oliver's school dinners campaign. Equally as certain is that if we don't heed the advice of an army of doctors, nutritionists and health workers, many won't live to tell the tale.

For more information about the York Nutrition Clinic, call 01904 343305.