Salt levels vary significantly in the fast foods sold by six major companies in various developed countries, which suggests that technical issues, often cited as barriers to salt reduction initiatives, are not the issue, according to a study in CMAJ (Canadian Medical Association Journal).

An international team of researchers from Australia, Canada, France, New Zealand, the United Kingdom and the United States looked at data on the salt content of 2124 food items in seven product categories from six companies.

The companies were Burger King (known as Hungry Jack's in Australia), Domino's Pizza, Kentucky Fried Chicken, McDonald's, Pizza Hut and Subway. They looked at savoury breakfast items, burgers, chicken products, pizza, salads, sandwiches and french fries.

Too much dietary salt has been linked to higher blood pressure and other adverse health effects. Estimates show that reductions in salt intake could result in a significant reduction in deaths. Several countries, such as the United Kingdom, Ireland, Finland, Japan and others, have embarked upon salt reduction efforts.

More recent efforts have been successful with voluntary salt reduction targets in place or labelling for some types of food. However, food companies often cite technical food processing issues as barriers to reducing salt content, stating that new technology and processes are needed to make lower-salt products.

Salt levels in similar foods varied widely between countries, with fast food in Canada and the US containing much higher levels of sodium than in the UK and France. In Canada, McDonald's Chicken McNuggets contained two and a half times the amount of sodium - 600 mg sodium (1.5 g salt) per 100 g serving compared to 240 mg sodium (0.6 g salt) per 100 g in UK servings.

"We saw marked variability in the reported salt content of products provided by major transnational fast food companies," writes Dr. Norman Campbell, University of Calgary, with coauthors.

"Canadian companies indicate they have been working to reduce sodium but the high sodium in these foods indicates voluntary efforts aren't working," states Dr. Campbell.

"These high levels indicate failure of the current government approach that leaves salt reduction solely in the hands of industry. Salt reduction programs need to guide industry and oversee it with targets and timelines for foods, monitoring and evaluation, and stronger regulatory measures if the structured voluntary efforts are not effective."

The authors write that this is an opportunity for widespread reformulation of products to contain lower levels of salt, a change that could be introduced gradually over several years to minimize consumer backlash.

"Decreasing salt in fast foods would appear to be technically feasible and is likely to produce important gains in population health - the mean salt levels of fast foods are high, and these foods are eaten often," they conclude.