Recently, the Evening Press' Experts column published a letter from a reader who suspected she might have a candida infection. York writer KATE LOCK shares her own experiences of this controversial condition.

A month ago I might not have been able to write this article. My brain was so fogged, my memory so poor and my concentration so fleeting that it would take me the entire morning to eke out a paragraph. Mentally, it was like floundering through mud. I was in deep trouble. I need to be creative: my living as a novelist depends on it.

I was also having a marital crisis, brought on by my mood swings, irritability and PMT. This had become so bad that for a fortnight before each period I would undergo a complete personality change. It was as if I'd been possessed.

I could hear myself snapping at my daughter and bullying my husband but I was powerless to stop. My husband had started to differentiate between 'good Katie' and 'evil Katie'. More often than not, Evil Katie seemed to be winning.

That's not all. I was suffering from such chronic digestive problems that eating had ceased to be a pleasure.

Food made me feel gassy and uncomfortable; I was bloated with fluid retention, and alcohol, cow's milk and wheat gave me rhinitis (in my case, a stuffed-up nose with claggy, hard-to-clear catarrh).

I was tired all the time and would fall asleep most afternoons, then wake up craving something sweet. After a fix of chocolate, my energy levels would soon crash and burn and by supper-time I'd be wiped out again and desperate for a glass of wine. This would make me woozy and two glasses would render me insensible. Even if I hadn't had a drink, I'd wake up the next morning feeling as if I had a hangover. There's no justice.

Now you might not think there's a connection between all these things, but there is. Together, they are a classic representation of systemic candida, an overgrowth of a naturally occurring yeast called candida albicans. Candida colonises our gut and, when it's kept in check by 'friendly bacteria', doesn't cause us problems. However, if there's an imbalance and candida is allowed to dominate, it can develop into a fungal form, triggering the litany of complaints above - and more.

Thrush, cystitis, irritable bowel syndrome, skin problems such as uticaria and itching, nail fungus, athlete's foot, migraines, joint pains - they're all pieces of the candida jigsaw.

Once it really gains a hold, candida can compromise the immune system. It's also been linked with ME, a wide range of gland disorders and cancer.

So how does this overgrowth come about? In my case it was the use of long-term antibiotics to treat acne. I can trace my symptoms back to my spotty teens and early 20s and this kind of time scale is not uncommon.

Antibiotics, which zap your intestinal flora (thus giving house room to opportunistic yeast cells), are the usual culprits, but there are others. Being on the contraceptive pill, HRT, taking steroids or immuno-suppressive drugs (eg for chemotherapy) also makes you vulnerable to candida. Finally, there's poor diet and the curse of modern life, stress.

Unfortunately, doctors aren't always sympathetic if you self-diagnose candida. A letter-writer to this page was told it wasn't possible, and I've been given short shrift myself in the past on not one but two occasions (both times I've been told, 'If you had candida that badly you'd be dying of AIDS').

This is partly because candida presents with such a wide range of apparently unconnected symptoms that conventional medicine doesn't accept there can be a single cause. It's also partly because, until recently, it was notoriously hard to test for. (This is no longer true, by the way. Simple, accurate testing kits are now available by post.)

Don't be put off: if you have medical problems, get them checked out by your GP. It's important to exclude other conditions and you may not have candida. Your doctor should be an ally - mine is, and I'm grateful for that - but it's equally vital that we as individuals assume responsibility for our health.

So, if you're still not satisfied, take action. Candida has been damaging my health for 20 years and I've had enough of it. A month ago, I decided it was crunch time.

Treating candida involves taking probiotics (lactobacillus acidophilus and bifidobacteria) to recolonise the gut, a variety of nutritional supplements to support your liver and immune system, digestive enzymes, gut-healing nutrients, anti-fungals to kill off the yeast and a bloody awful diet. Sorry, but there's no other way to describe it.

The idea is to starve the candida by depriving it of everything it - and you (because you'll probably be addicted to the worst things) love. This means nothing containing sugar or yeast, no refined carbohydrates such as bread, biscuits, pasta or pizza, no fermented foods, no vinegar-containing foods, no alcohol, no dairy products, no wheat, no mushrooms, no dried fruit and not, in the early stages, much fresh fruit, either. Tea and coffee are also banned. And don't even think about chocolate.

I won't pretend it's easy. The diet is difficult to stick to, time-consuming, frequently impractical (not to mention anti-social), expensive and requires a great deal of commitment. But before you give up and reach for the biscuits, think about what you've got to gain. Getting your health back has got to be worth it.

If you can, work with a nutritional therapist or other complementary practitioner, someone who can steer you through it. I've found acupuncture helpful for specific problems, too.

Read all you can - I recommend Beat Candida Through Diet by Gill Jacobs and Joanna Kjaer (Vermillion) - and join the National Candida Society for information and discounts. They run support groups, too. There isn't one in York, but if there is the interest I'd consider setting one up.

I've only been on my anti-candida regime for a month - you need to do it for three, possibly even six months if your candida's really bad - but already it's made a huge difference.

After a week, my muddy mind had cleared and I was able to focus again. Within two weeks my digestive problems had started to improve. My joint pains went. My fatigue vanished. I woke up ready to face the day without feeling as if I'd been socked over the head.

I've had no migraines, no thrush, and, best of all, no PMT. Good Katie's back, and this time she's staying.

Oh, and by the way: I've also dropped two dress sizes, got a flat stomach for the first time in years and, surprise, surprise, lost my cellulite. And I wasn't even trying...

The National Candida Society can be contacted at PO Box 151, Orpington, Kent, BR5 1UJ or visit its website at: www.candida-society.org.uk

Anyone interested in a local support group should email me at Kate@klockworks.co.uk or write to me c/o Maxine Gordon at the Evening Press, 76-86 Walmgate, York, YO1 9YN.