Chances are you'll know people who have cut down on or given up eating wheat and wheat products and say they feel better for it. You may also know someone with coeliac disease who genuinely has to avoid any foods containing gluten because if they have even the tiniest bit they will get very sick.
In many restaurants and on many food products you'll see the words "gluten-free" or the symbol of an ear of wheat with a slash through it, rather like a no-smoking symbol.
An increasing number of companies market gluten-free products. Virginia O'Leary, of Auckland-based food manufacturer Wild Appetite, says labelling her products "gluten-free" is a better marketing tool than labelling them "organic".
Sourcing organic ingredients is difficult and expensive and her dressings, chutneys and preserves would not normally contain gluten anyway.
"There are a lot of neurotic people around who don't eat bread and are making their life unnecessarily inconvenient," Prof Mann said.
However, there are many shades of grey between people with coeliac disease who cannot tolerate the smallest amount of gluten and those who simply feel better eating fewer foods made with wheat. Food intolerances and autoimmune diseases seem to have increased in frequency, he says. Coeliac disease is an intolerance to dietary gluten in which the cells of the small intestine are damaged and are unable to absorb nutrients from food.
It is likely there is a genetic link but which genes are specifically responsible is not yet determined. Probably 98% of people with the disease have either human leucocyte antigens HLA-DQ2 or HLA-DQ8, but about a third of the population without the disease also have one or two of them.
Coeliac disease is diagnosed by a range of blood tests and, most importantly, a small bowel biopsy which is regarded as the "gold standard".
Gluten is a protein found in wheat, rye, and barley. Gluten's rubbery, elastic properties are essential in breadmaking and baking. Wheat products, such as flour, starch, cornflour and other thickeners and malt (from barley), are found in many processed foods, from soy sauce and baking powder to packet soups and sauces, beer, sausages, some yoghurts and even lollies. Most pastas and many breakfast cereals are made from wheat.
It is not clear how many people suffer from coeliac disease or milder forms of gluten intolerance. At one end of the scale, Dr Rodney Ford, of Christchurch, who styles himself "Dr Gluten", claims one in 10 people are adversely affected by gluten which, he says, conventional medicine does not recognise.
Symptoms of gluten sensitivity range from chronic fatigue, anaemia, diarrhoea, flatulence, constipation, indigestion and bloating, to dermatitis herpetiformis, headaches, depression, irritability, hyperactivity, learning problems, poor appetite, poor growth and frequent malaise.
Because most people eat gluten every day, they never get a chance to see how they would feel without it.
Gluten is sapping the energy and wellbeing of countless millions to which the medical profession is turning a blind eye, Dr Ford claims.
However, even if one in 10 people are adversely affected by gluten, that means 90% of the population is not.
More conservatively, Dr Martin Schlup, a consultant gastroenterologist and senior lecturer at Otago University, says it is more likely one in 100 or one in 200 have genuine coeliac disease in Western countries.
Doctors are more aware of coeliac disease and diagnose it more often than in the past.
He describes it as like the tip of an iceberg - for every case diagnosed, many others go undiagnosed.
But it is unclear what proportion of the population are gluten-sensitive.
"I see quite a few people who go on the so-called gluten-free diet and say they feel a lot better.
"We check them out for coeliac disease and they don't have coeliac disease, but they still feel better if they eat less wheat and wheat products," Dr Schlup said.
"Often it isn't a strict gluten-free diet; it's a reduction in wheat products that seems to achieve the desired outcome. Food intolerance is a very difficult field."
Besides a placebo effect, there are other reasons people may feel better eating less bread, baked goods and wheat products - one is that they are simply eating less.
Dr Schlup says there is evidence that 10%-30% of carbohydrates eaten are not fully digested and go through the system into the large bowel where they are digested by bacteria which can generate gas and make people feel bloated.
"If these basic physiological events are perceived in an exaggerated way and people reduce carbohydrate intake and therefore have less wind, they may feel better."
The gut is a miraculous organ, he says.
"On the one side it needs to accept all the stuff we eat and allow absorption of that, and on the other if there is something among all that stuff we eat, a virus or bacterium that doesn't belong there, the gut [needs to] recognise it.
"The gut has dual roles which are almost opposite to each other and generally it manages to distinguish between these two and that is why we survive."
Modern, hybrid wheats
Besides the fact that doctors are more aware of gluten sensitivity and are diagnosing coeliac disease more often, there are many theories but few certainties to explain why it and other autoimmune diseases and food allergies are more common these days. One is that modern hybrid wheats with higher gluten content used in bread and pasta are to blame. One theory claims the rate of coeliac disease in New Zealand went up when we imported more Australian hard wheats.
Some people who give up eating modern wheat still eat ancient types of wheat such as spelt and kamut. Some say that humans evolved on a hunter-gatherer diet with lots of vegetable foods and meat, and some have not adapted to grains which became a major part of the human diet about 10,000 years ago with the development of agriculture.
However, it is now thought that coeliac disease occurs in all races in about the same proportions, even in peoples whose traditional diets do not include wheat.
Another hypothesis says allergies are more common in our society because of increased hygiene and antibacterial cleaners. Children are not exposed to dirt and their immune systems do not develop as they used to.
Then there's a claim that pesticide and herbicide residues on our food and additives and preservatives in processed food upset our systems.
However, although there may be anecdotal support, there appears little scientific evidence for any of these theories at present.
Whole grains nutritious
Whole grains and cereals, such as wheat, barley, corn and rice, are generally recommended as part of a healthy diet, and the food pyramid recommends eating six servings a day (a serving is equivalent to a slice of whole-grain bread).
For people who don't have an intolerance, whole grains are a nutritious food and also provide a lot of fibre, but there are other ways you can get your nutrients, Prof Mann says.
However, if you eliminate a major food like wheat from your diet, you should get nutritional advice on alternative foods to replace the nutrients you will be losing.
Millene Campbell, of the Coeliac Society support group in Dunedin, says the gluten-free diet is one of the most difficult to adhere to, but it can be done. Some coeliacs also have other conditions, such as diabetes or a dairy allergy, and need to combine several restrictive diets which is even more difficult.
There are an increasing number of gluten-free products available in supermarkets now but it is an expensive diet to maintain as they often cost more, she says.
Even some foods that do not contain gluten can be unsafe for coeliacs because of contamination.
Oats are generally not recommended because they are usually processed in the same equipment as wheat. Gluten-free bread baked in a regular bakery may also be contaminated by the flour in the air, as may gluten-free food cooked in a restaurant kitchen, she says.
People with coeliac disease react differently to even small amounts of gluten - they may have violent diarrhoea or constipation, or have migraines or feel as if they have a massive hangover. Or the effects may be more subtle such as intestinal damage, she says.
People on restrictive diets also find it difficult to eat out in cafes and restaurants. You need to look carefully at the menu and ask lots of questions.
While some Dunedin restaurants are knowledgeable and happy to offer gluten-free dishes, staff in others do not understand the requirements. It's even more difficult to find restaurants that cater for coeliac children, she says.
For more information:
Disability Information Service, 283 Moray Pl, Dunedin.
Phone (03) 471 6152
www.disabilityinfo.co.nzwww.coeliac.co.nzwww.doctorgluten.comwww.nutriti...
