Gluten-free is one of the hottest topics in the food industry.
All manner of products - cereal, cake mix, pasta, even beer - are making the jump from niche stores to the big supermarkets. Celebrities tout a gluten-free diet as a way to lose weight and feel healthier. Big food manufacturers and supermarkets in Australia and the US are investing heavily.
Gluten is a problem for the small group of people who have coeliac disease or gluten sensitivities. Coeliac sufferers' diets must be free of gluten (a protein found in wheat, barley and rye), and those sensitive to gluten should avoid it.
An estimated 1 per cent of Australians and Americans have coeliac disease, and for them, as well as those with gluten sensitivities, the growing variety of gluten-free food is a godsend.
But for most of the population, there's no proof a gluten-free diet offers any benefit - and it's costly. For example, a 750-gram pack of gluten-free flour in an Australian supermarket costs up to $6 - two or three times more than normal flour.
Demand for gluten-free products is growing exponentially. In July, Coles introduced its ''Simply Gluten Free'' range: 40-plus products (including pasta, pancake mix, muesli, Anzac biscuits, cheese twists, cake mixes and biscuits). Coles says it's responding to strong demand from shoppers. The supermarket offers a 5 per cent discount on 60 gluten-free products to financial members of Coeliac Australia.
One of the reasons for the gluten-free boom, market analysts say, is the buzz bestowed by celebrities. Gwyneth Paltrow has talked about her cleansing regime that includes giving gluten a wide berth, while Oprah Winfrey went on a no-gluten cleansing diet.
''There are a lot of misconceptions about the gluten-free diet out there,'' the communications director for America's National Foundation for Coeliac Awareness, Whitney Ehret, says.
Gluten, an essential component in making cakes fluffy and biscuits chewy, has in a way become demonised. Some products billed as gluten-free never contained gluten to begin with, but marketers want to capitalise on the sudden health halo.
In the US, retail sales of gluten-free products rose from an estimated $US935 million ($1.02 billion) in 2006 to an estimated $US2.64 billion in 2010, according to a February report by market researcher Packaged Facts.
Datamonitor's Product Launch Analytics, another US market researcher, found 13.4 per cent of all food products launched there in 2010, excluding beverages, made a gluten-free claim, compared with 5 per cent in 2005.
''It's pretty unusual to see that sort of major advance over that brief a period of time,'' Product Launch Analytics' director, Tom Vierhile, says.
In people with coeliac disease, gluten causes the body to attack itself by destroying ''villi,'' tiny finger-like protrusions lining the small intestine that are vital for absorbing nutrition.
One per cent of Australians have coeliac disease, and executive director of Coeliac New South Wales and ACT, David Sullivan, estimates three-quarters of them are undiagnosed. That means only 0.25 per cent of Australians are coeliac and know it.
Yet Sullivan says a study conducted by the Coeliac Research Fund in late 2010 showed about 10 per cent of Australians are either strictly controlling or limiting gluten in their diets.
And ''anecdotally'' that number appears to be increasing, Sullivan says, ''as reflected by the significant increase in gluten-free products now available''. In a US survey by Packaged Facts last year, 20 per cent of consumers said they bought gluten-free products because a member of their household had coeliac disease or was gluten-sensitive. But 46 per cent purchased gluten-free for the perceived health benefits. Another 30 per cent said they bought gluten-free to manage weight, while 22 per cent did so because they believed they were lower in carbohydrates.
The Packaged Facts report notes that neither the weight-management nor lower-carb claim is true. ''But consumers tend to think otherwise.''
Yet coeliac disease remains a serious medical condition - one that Sullivan believes is ''underdiagnosed'' by doctors. That may be because symptoms vary widely, from mild and non-specific to severe and debilitating.
''Understandably, CD is often not the first consideration when a patient presents with issues such as lethargy and gastrointestinal symptoms,'' Sullivan says. ''Irritable bowel, gastroenteritis, stress, vitamin and mineral deficiencies and other common health complaints may be treated in isolation and delay a diagnosis of CD.'' But a lot of self-diagnosis is going on.
''Self-diagnosis is definitely increasing as more information becomes readily accessible through social media,'' Sullivan says. ''The danger of self-diagnosis is that symptoms in coeliac disease can be similar to those in other serious health conditions such as inflammatory bowel disease or intestinal cancers. An assumption of CD without proper testing may delay or prevent a diagnosis of these conditions.''
He advises people who think they might be coeliac to seek medical advice before going gluten-free.
''The tests for coeliac disease rely on the continuing consumption of gluten to ensure accurate results. Symptoms should be discussed with a medical practitioner, who should assess related risk factors and may order an initial blood screening test.
''If the results of the test are positive, the patient should be referred to a specialist gastroenterologist for a diagnosis. At present, the accepted standard for diagnosing coeliac disease is through a small bowel biopsy to confirm bowel damage.''
>> Anyone unsure about their symptoms or what they should do can call Coeliac Australia on 1300 GLUTEN, or visit the website at coeliac.org.au.