Close to half the energy value in combat ration packs comes from wheat products with many unsuccessful applicants and family members frustrated by the army's rigid guidelines.

"Those declaring severe gluten intolerance such as a history of coeliac disease are considered medically unsuitable for entry," a Department of Defence spokesman told Fairfax Media.

"Coeliac disease management requires strict adherence to a gluten free diet and unfortunately such obligatory dietary restrictions are not compatible with military duties."

Annie Smith, a 20-year-old Canberra resident, was diagnosed with coeliac disease in 2013 after she completed high school and believes the ADF's position is unfair and inflexible.

"I wanted to join either the army or the airforce because I wanted to serve my country just like my grandparents did," she said.

"I can see where they are coming from but I still think it is not fair. It's not that much of a change and they allow for other people with allergies to join, but not us."

Her grandfather, Ken Castle, said the policy was discriminatory given the force had announced plans to make one third of all rationed meals halal-certified to create an inclusive workforce.

"This seems to me to be discrimination of the highest order," he said. "[She] is from a long-time Australian past and is prepared to serve Australia in our defence force which is a family tradition."

Cameron Chalmers was turned down by the Navy as an 18-year-old in 2012 due to his condition and said he would apply again if he had the opportunity.

"I think that food technology has advanced in the past few years to the point where they should be able to support people who have an intolerance," he said.

For those with coeliac disease, consuming gluten can cause inflammation and damage to intestine lining. For those with allergies or sensitivities, it can cause gastrointestinal symptoms..

Coeliac disease affects one in 70 people although 80 per cent of affected Australians remain undiagnosed and unaware they are living with the condition.

Support group Coeliac Australia, which will launch a national awareness week on Saturday, have developed a standard response for frustrated applicants.

"You are not alone in this predicament as we have had many calls and emails regarding the same issue," the response says.

Coeliac Australia president Tom McLeod said his organisation would engage with the ADF to ensure those with coeliac disease could be catered for.

Paul Bertrand, a head of RMIT's gut neuroscience laboratory, said the ADF's position on gluten intolerance and coeliac disease was reasonable and common among other militaries.

"Certainly, providing foods that do not contain wheat – which is a very big list of processed foods – is possible, but I cannot comment on whether this is feasible," he said.

"Whether or not a person could perform a sedentary task while having a coeliac disease flare up is fairly specific to the task, the person and the amount of gluten eaten they've eaten."

Dr Bertrand said supplying a coeliac with current ADF ration packs would have "severe consequences for their health in the short term".

"Generally, the lining of the gut is badly damaged and takes a few weeks to heal. While the damage is present, the person would cause bloating and diarrhoea," he said.

"If they continued to eat these rations, I would expect weight loss and malnutrition – and eventual hospitalisation for, at the least, nutrition given through an intravenous line".

The defence spokesman said the ADF had "a duty of care to ensure its members are not placed at an increased risk of harm or injury under normal conditions of service".

"It is also essential that entrants to the ADF do not have any medical condition which may be exacerbated in a military environment and the entry standards are in place to protect the health and safety of the individual," he said.

Close to 100 applicants are denied entry to the ADF each year on average, according to the Department of Defence.

Fairfax Media requested five years of data from the department although only five months were provided due to a change of record systems.