The study, published on May 13 in JAMA Internal Medicine, showed that the average sodium content in 402 packaged foods only decreased 3.5% between 2005 and 2011. In addition, 78 items found in chain restaurants increased in sodium during that same time frame by 2.6%.

"The strategy of relying on the food industry to voluntarily reduce sodium has proven to be a public health disaster," author and Center for Science in the Public Interest (CSPI) executive director Michael F. Jacobson said in a press release. "Inaction on the part of industry and the federal government is condemning too many Americans to entirely preventable heart attacks, strokes, and deaths each year."

The study was conducted by non-profit consumer advocacy group, CSPI. Researchers looked at mean sodium levels for identical food products that were collected in 2005, 2008 and 2011. Although some products decreased in sodium content by as much as 30%, the majority of products increased their sodium by at least 30%.

Researchers have stated that excess sodium intake, which is mostly obtained from dietary salt, may lead to the deaths of 2.3 million people across the world annually. The figure was derived from 250 surveys of salt consumption that were part of the 2010 Global Burden of Diseases Study, as well as more than 100 medical trials that measured the effect of sodium on increasing blood pressure, stroke risk and heart disease risk.

The American Heart Association (AHA) adds that for one-third of Americans that develop high blood pressure, eating too much salt may be the culprit. Sodium may increase blood pressure because it retains fluid in the body, which puts more stress on the heart. Excess salt can also increase the risk for stroke, heart failure, osteoporosis, stomach cancer and kidney disease.

The U.S. government recommends no more than 2,300mg of sodium a day, while the AHA says that eating no more than 1,500mg daily will help people avoid hear disease and stroke risk. The AHA has found that Americans are eating 3,400mg per day on average.

In February, New York City Mayor Michael Bloomberg announced that 21 companies have voluntarily reduced the sodium content in their products as part of the 2010 National Salt Reduction Initiative.

Bloomberg at the time lauded Kraft for reducing sodium in its Kraft Singles American Slices by 18% and Subway for getting rid of some sodium in two of their sandwiches, including his favorite Italian BLT. Other popular foods included were Unilver's Ragu Old World Style Traditional Tomato Sauce and Nabisco's Teddy Grahams Honey snacks.

New York City has attempted to lower salt consumption with advertisements asking citizens to take a closer look at the sodium content in packaged foods and make an active choice to choose a healthier option. Mexico City launched a voluntary campaign to remove salt shakers from restaurant tables, and the government is encouraging restaurant owners and workers to only provide them if the patron requests it.

"The current high levels of sodium in packaged and restaurant foods, if not reduced, will likely cause at least one million deaths and $100 billion in health-care costs in the coming decade," author Dr. Stephen Havas, professor of preventative medicine at Northwestern University Feinberg School of Medicine, said in a press release. "Action by the FDA requiring the food industry to lower sodium in our food supply is long overdue and should begin without further delay. The Obama administration should take action forthwith."