Food companies are declaring products have "No added MSG" despite using ingredients that are ultimately chemically indistinguishable from the flavour enhancer, sparking accusations of misleading labelling.
Companies such as Coles, Campbell's and San Remo are using the claim on foods that contain ingredients such as hydrolysed vegetable protein and yeast extract, which experts say are chemically the same as MSG.
The Food Intolerance Network, made up of 10,200 families in Australia and New Zealand, said not only was the claim often misleading, but companies were using at least 129 different terms and forms of MSG to "confuse" consumers.
"The food industry preys on our ignorance. MSG is monosodium glutamate. There are lots of ways to break down proteins to release glutamates. Added glutamates then look like an anonymous ingredient in the food," said Howard Dengate, food technologist and co-founder of the group.
"Who would think that 'soy protein' or 'vegetable protein extract (corn)' might be MSG in another form, added legally but avoiding regulation as an additive?"
A scan of supermarket shelves by Fairfax Media found dozens of processed foods which used 'No added MSG' as a selling point but had ingredients and additives which were chemically the same as or contained the flavour enhancer.
Some Continental pasta products, Red Rock Deli chips, Mamee Monster rice sticks and Campbell's soups were labelled 'No added MSG' when they contained yeast extract.
Natural Chip Company chips contained vegetable extract, and some San Remo pasta and Patties' beef pies contained hydrolysed vegetable protein despite being labelled 'No added MSG'.
Professor Merlin Thomas, who heads the biochemistry of diabetic complications laboratory of the Baker IDI Heart & Diabetes Institute, said because MSG had a bad reputation, many manufacturers were using other sources of glutamate to achieve the flavour kick.
"These include vegetable, corn, yeast or soy protein extracts, in which the glutamate has been released from the protein by enzymatic digestion or chemical hydrolysis," he said.
"When dissolved in water, the free glutamate in these extracts is chemically identical to that contained in MSG and enhances flavour in precisely the same way."
But he added that rigorous studies over the decades had failed to confirm a firm link between the consumption of large amounts of glutamates and health impacts cited by self-described "MSG sensitive" people, who claim they have symptoms such as headaches, numbness and weakness.
"Most reactions have little to do with the MSG, as many of the same people who are 'MSG sensitive' have no problems with Vegemite or parmesan cheese," he said.
Mr Dengate said the key issue was that consumers who wish to avoid MSG should easily be able to do so and not be misled by 'No added MSG' claims.
"Consumers shouldn't have to remember over 129 names of ingredients if they are trying to avoid glutamates. Instead, all food companies should make the simple statement on their ingredient panels 'May contain naturally occurring glutamates'," he said.
In February 2012, supermarket behemoth Coles announced it was banning the use of "added MSG" in its products, saying "our customers are clearly concerned by food additives and the effect they believe they have on their health".
Fairfax Media found a slew of Coles products with the 'No MSG' claim which contained hydrolysed vegetable protein, hydrolysed wheat and soy protein, including in its sausage rolls, meat pies, pizzas and rice crackers.
A Coles spokesman said: "Coles Brand products have detailed ingredient lists to assist customers in making informed choices."
Woolworths products that have the 'No added MSG' claim, such as Homebrand instant noodles and flavoured noodle cups, have a line on the back saying: "May contain naturally occurring or other forms of glutamates".
Mr Dengate called this "best practice".
In the United States, the law dictates foods with any ingredient that naturally contains MSG cannot claim 'No MSG' or 'No added MSG' on the packaging. These ingredients include hydrolysed vegetable protein, yeast extract and soy extract.
A Food Standards New Zealand and Australia spokesman said 'MSG free' and 'No added MSG' were not classified as health claims and therefore not under its jurisdiction.
"FSANZ advises [companies] that care may be needed in using these types of claims, as MSG can be naturally present in some foods," she said.
"Consumers can check the label if they are concerned about the presence of added MSG or added permitted glutamate food additives."
The Australian Competition and Consumer Commission regulates the use of the claims. It declined to answer whether a company stating 'No added MSG' on a product that contains, for example yeast extract, was misleading shoppers.
"Under the Australian Consumer Law, it is illegal for a business to make representations that are incorrect or likely to create a false impression," a spokesman said.
An Australian Food and Grocery Council spokesman said the claims must be truthful and accurate.
"The 'No added MSG' claim means that glutamate has not been added and it may be necessary, for example, to qualify in the context of the claim that the food contains ingredients with naturally occurring glutamate," he said.
"There is no wriggle room for companies, otherwise they risk significant financial penalties."