Like gluten, sugar and lactose, nitrates appear to be next on the list of foods some Australians have decided to cut out of their diets.

Butchers and supermarkets are increasingly selling nitrate-free bacon, which is often twice the price of bacon that's been cured using sodium nitrate.

Butcher Blair Parsons said customers started asking for nitrate-free bacon about four years ago, prompting him to experiment with alternative preservatives and curing agents.

After some trial and error, Mr Parsons started using a cure of salt, sugar, water and sodium ascorbate which, as a food additive, has the code E301.

His shop in Bunbury, in the south-west of Western Australia, sells about 40 to 50 kilograms of nitrate-free bacon a week and he said demand continued to grow.

Butcher Blair Parsons with two types of bacon. The bacon on the left was cured with sodium nitrate and the bacon on the right was cured without nitrates. ( ABC South West WA: Anthony Pancia )

Why buy nitrate-free bacon?

Some people do not like the salty taste left on the meat by sodium nitrate, while others say they believe their bodies react badly when they eat bacon cured with nitrates.

But most cite heath concerns as their primary reason for avoiding sodium nitrate, and point to studies that suggest the body converts nitrates to produce potentially carcinogenic compounds when digested.

Are nitrates really that bad?

Accredited practising dietician Jacklyn Jackson said the idea that nitrate-cured bacon was bad came from the fact that increased intake of processed meats led to an increased risk of some cancers.

"What a lot of people don't realise is that vegetables are the major contributor to our dietary nitrate exposure and can account for approximately 40 to 80 per cent of nitrates we consume, while processed meats generally only account for less than 10 per cent," she said.

Ms Jackson said dieticians could not say for sure what happened to nitrates in the body because each person's reaction was dependant on the presence of other bacteria, the level of oxygen in the blood, as well as other nutrition factors like antioxidants, fat and alcohol.

"In the stomach, nitrate is converted to nitric oxide and a range of other nitrogen-containing compounds," she said.

"Nitric oxide is an extremely beneficial molecule for cardiovascular health and has a role in regulating blood pressure and the function and structure of the blood vessels.

"Nitrates might actually be good for you."

The bi-national government agency Food Standards Australia and New Zealand says "consumers should be reassured that exposures to nitrates and nitrites in foods are not considered to represent an appreciable health and safety risk".

Most bacon is cured using the food additive sodium nitrate, but some people want to avoid eating the commonly used preservative. ( ABC South West WA: Anthony Pancia )

Ms Jackson said people should not worry about eating bacon cured using sodium nitrate, as long as they watched how much, and how regularly, they ate processed meat.

"As a general rule, the Australian Dietary Guidelines recommend people limit their consumption of processed meats like bacon, ham and sausages, regardless of how they have been marketed to us, as they have been shown to increase our risk of colorectal cancer," she said.

"If you're limiting your intake of processed meat to once a week, you'll be alright."