Imagine not being able to enjoy all those breads, pastas, pastries and cakes?

Lots of people opt for gluten-free foods these days, perhaps in a bid to avoid bloating or as part of a weight-loss regime. But for people with coeliac disease, avoiding gluten - a protein in wheat, barley and rye that's found in foods containing flour, and a prominent feature in most breads, pastas, cereals, pastries, cakes and biscuits - is not a lifestyle choice but a medical necessity.

SERIOUS COMPLICATIONS

What sets coeliac disease apart from straightforward food intolerances is the fact it's an autoimmune condition, where the body mistakes something 'normal' as a threat and attacks healthy tissue.

In this case, eating gluten - even tiny amounts - triggers the immune system to launch an attack which damages the lining of the small bowel/intestines, resulting in symptoms including bloating, diarrhoea, nausea, wind, constipation, tiredness, sudden or unexpected weight loss (though not always), hair loss and anaemia. Chronic mouth ulcers are another symptom.

As well as being deeply unpleasant and making people feel very unwell, over time, continuing to eat gluten can lead to very serious complications for people with coeliac disease.

Anaemia can occur because gut damage means people can't absorb iron sufficiently. Difficulty absorbing nutrients may also explain why some people with coeliac disease develop persistent mouth ulcers - which may also be linked to the immune system attacking the body via the mouth - and can lead to a host of long-term problems, including osteoporosis.

"If coeliac disease isn't treated at all, it could have very serious consequences," warns Coeliac UK's chief executive, Sarah Sleet. "These include osteoporosis, which can be a devastating disease, increased infertility in some women, and increased risk of a rare small bowel cancer. "

UNDER-DIAGNOSED

It's believed that one in 100 people in the UK have the condition, but only 24% of them have been diagnosed - meaning there are nearly half a million Britons who are unaware they have coeliac disease.

That's why, to mark this year's Coeliac Awareness Week (May 11-17), Coeliac UK is launching the 'Is it coeliac disease?' campaign, along with the UK's first online assessment. After answering a series of questions based on doctors' guidelines on the potential signs of the condition, people will be advised to arrange a medical consultation, so they can be properly tested, if necessary.

"With half a million people living with undiagnosed coeliac disease, we must take radical action to turn around this horrendous situation," says Sleet. "We hope giving people direct access to an online assessment tool will put those who are suffering with the symptoms of undiagnosed coeliac disease on a pathway to diagnosis, and avoid potentially life-threatening long-term health complications, as well as helping reduce the unacceptable length of time to gain a diagnosis, which is currently, on average, 13 years."

TESTING TIMES

It's not unusual for people with coeliac disease to initially be diagnosed with conditions like irritable bowel syndrome (IBS), which may share similar digestive symptoms but doesn't pose the long-term health risks associated with coeliac disease.

But the disease does have a very clear pathway, as the antibodies produced in coeliac disease show up in blood tests. However, getting these results depends on people being referred for the test. And if people are already following a gluten-free diet, the results might not be accurate.

A confirmed diagnosis enables people to receive appropriate follow-up care and support, as well as providing evidence for close family members to also be tested if necessary.

Actress Caroline Quentin is close to completing her own diagnosis journey after an initial positive blood test two years ago, and a more recent genetic test. "Coeliac UK's campaign to reach the half a million people still undiagnosed with coeliac disease really resonates with me, because I struggled for years with constant stomach pains, vomiting and total exhaustion," she says.

WHO GETS IT?

It can strike at any age, from when children start eating gluten as babies, but the most common time to be diagnosed is middle age, often because of delayed diagnosis.

Autoimmune diseases, in general, are a bit of a mystery, but research suggests that some people may have a genetic disposition to developing them. This means people with a first-degree family member (such as a mother, father, sister or brother) with coeliac disease, might be more likely to develop it.

However, having a family member with coeliac disease doesn't mean you're guaranteed to get it - and having no family history doesn't mean you won't get it either. "About a third of the UK population have the genes involved with the disease, but only 1% of them go on to develop it," says Sleet.

The ' hygiene hypothesis' is one of the theories which could account for this.

"Autoimmune diseases are on the rise, and the thinking behind the 'hygiene hypothesis' is that if bugs don't challenge you in the right time frame and in the right way, then your immune system doesn't get switched on properly. In a super-clean environment, where you're not facing these challenges in the early years, maybe your immune system isn't getting triggered properly, and doesn't learn to respond to threats.

"But nobody's really nailed the cause for sure," she stresses.

There's also a lot of research around the role of 'triggers' in autoimmune conditions; being genetically predisposed is one factor, but it could be a 'trigger' - perhaps a virus, trauma or the existence of another health condition - which activates the disease.

GLUTEN-FREE FOR LIFE

Once diagnosed, the only treatment is following a gluten-free diet for life. Fortunately, these days there are a variety of gluten-free products available.

Sleet says: "Living with coeliac disease can be very difficult, although it's got a lot easier because there are more gluten-substitute products available. The quality of the products varies, although it's improved hugely from the days when there used to be tinned gluten-free bread."

Cost is often a significant issue, as gluten-free varieties of breads and flours, for instance, are around three to four times as expensive as regular products.

"People struggle to get the quality they were used to," adds Sleet. "And research shows that a significant number of people really find it difficult to maintain a strict gluten-free diet."

Part of this struggle is because of 'hidden' gluten, such as wheat flour used in processed foods either as a thickener or a flavour carrier, or barley malt extract used as a colour or flavour in processed foods. Gluten is often used as an ingredient in many favourite foods, like fish fingers, sausages, gravies, sauces and soy sauce, too.

EXPERT GUIDANCE

"You can get proper advice about managing your diet," says Sleet. "If people don't get the right advice, they can be so restrictive on their diet that they're not getting all the nutrients.

"The other extreme is that they don't avoid gluten entirely, and even at a low level, the ingestion of gluten is still causing gut damage.

"You have to read all the labels, and that's really time-consuming, but the labels don't always tell you if the product is at risk of cross-contamination. All in all, it's not a simple diet."

But it is essential.

:: For more information, and to find the 'Is it Coeliac Disease?' online assessment, visit www.isitcoeliacdisease.org.uk, or call the Coeliac UK helpline on 0845 305 2060