A research review suggests just 16 per cent of people who report gluten intolerance actually suffer symptoms when challenged in placebo blind study.

Only a small proportion of Australians who claim to be gluten intolerant may actually display symptoms, say researchers.

With a gluten-free diet linked to poor health, researchers at the University of Newcastle have warned of people changing their diet without a formal diagnosis of non-coeliac gluten or wheat sensitivity (NCG/WS).

"It is likely that only a small proportion of Australians who associate adverse symptoms with gluten ingestion are truly sensitive to gluten or wheat. Little is known about the incidence of this disorder," they write in the Medical Journal of Australia.

It's estimated up to one in 100 people in Australia have coeliac disease, where the immune system reacts abnormally to eating gluten.

Another seven per cent of Australians report adverse gastrointestinal and/or extraintestinal symptoms, such as bloating and cramping, after eating wheat products which contain gluten.

However a paper, published in the Medical Journal of Australia, shows only 16 per cent of those to report a sensitivity to gluten actually reproduced symptoms when challenged in a blind placebo study. That is they ate gluten without being aware of it and didn't suffer any adverse reactions.

The authors of the paper, led by Michael Potter from the Hunter Medical Research Institute, say it is very difficult to to diagnose NCG/WS once coeliac disease has been excluded.

Despite this, they are urging people to only change their eating habits if formally diagnosed with coeliac disease because a gluten-free diet has "several drawbacks" for health.

"Several studies have demonstrated that gluten-free diets may not provide adequate amounts of trace elements and vitamins such as calcium, vitamin D, folate, thiamine, riboflavin and niacin," the authors said.

"A gluten-free diet may adversely affect cardiovascular risk factors such as total cholesterol levels, weight gain leading to obesity, glucose tolerance and blood pressure and may lead to development of the metabolic syndrome," they add.

A recent US study published in the British Medical Journal found an association between a gluten-free diet and a increased risk of heart disease among 110,000 men and women.

Analysis also showed restricting gluten might lead to a lower intake of beneficial whole grains.

"The promotion of gluten-free diets among people without coeliac disease should not be encouraged," the researchers said.