WASHINGTON — Reductions in sodium levels in processed and restaurant foods from 2005-11 were inconsistent and slow based on samples used in a study that appeared on-line May 13 in JAMA Internal Medicine, formerly Archives of Internal Medicine. Between 2005 and 2011, the sodium content in 402 processed foods declined by about 3.5%, but the sodium content in 78 fast-food restaurant items increased by 2.6%.

“The strategy of relying on the food industry to voluntarily reduce sodium has proven to be a public health disaster,” said Michael F. Jacobson, Ph.D., executive director of the Washington-based Center for Science in the Public Interest and a researcher in the study. “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.”

Other researchers were Stephen Havas, Ph.D., professor of preventive medicine at the Northwestern University Feinberg School of Medicine in Chicago, and Robert McCarter, a biostatistician at George Washington University and the Children’s National Medical Center in Washington.

“The current high levels of sodium in packaged and restaurant foods, if not reduced, will likely cause at least 1 million deaths and $100 billion in health care costs in the coming decade,” Dr. Havas said. “Action by the F.D.A. 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.”

In responding to the study, the Washington-based National Restaurant Association said new menu items that are lower in sodium were not included in the study since the study only compared items available in 2005.

The N.R.A. added only 78 restaurant products were sampled while thousands of menu items are available and the study’s results do not accurately reflect the entire restaurant industry since it focused solely on quick-service restaurants.

“Restaurants have made significant progress in developing lower sodium menu options,” said Joy Dubost, Ph.D, R.D., director of nutrition for the N.R.A. “The industry is highly diverse, including restaurants that provide a wide range of dining options. On the whole, our members have evaluated their product lines to determine the areas in which sodium can be reduced, reformulated existing menu items when feasible, and considered sodium levels as part of new product development. The industry’s proactive and ongoing efforts will better enable the gradual reduction of sodium in the food supply.”

The C.S.P.I., in collecting Nutrition Facts labels on food products in 2005, 2008 and 2011, found evidence of sodium reduction in some categories. Fresh or frozen pork, canned diced tomatoes, canned white tuna, vegetable soup and sliced turkey breasts all saw average sodium reductions of more than 20%.

The results were different for 12 varieties of barbecue sauce, which saw an average sodium increase of 6.3% from 2005-11, 11 varieties of Caesar salad dressing, which saw an average increase of 3.7%, and 7 varieties of 100% whole wheat bread, which saw an average increase of 3.6%.

Although some products showed decreases of at least 30%, a greater number of products showed increases of at least 30%. Sodium levels varied among brands of similar products. One brand of tomato paste had a level of sodium more than 5 times as high as a sodium level in another brand of tomato paste.