WASHINGTON — Food companies and restaurants could soon face government pressure to make their foods less salty — a long-awaited federal effort to try to prevent thousands of deaths each year from heart disease and stroke.

The Food and Drug Administration is preparing to issue voluntary guidelines asking the food industry to lower sodium levels, FDA Commissioner Margaret Hamburg told The Associated Press. Hamburg said in a recent interview the sodium is “of huge interest and concern” and she hopes the guidelines will be issued “relatively soon.”

“We believe we can make a big impact working with the industry to bring sodium levels down, because the current level of consumption really is higher than it should be for health,” Hamburg said.

The food industry has already made some reductions and has prepared for government action since a 2010 Institute of Medicine report said companies had not made enough progress on making foods less salty. The IOM advised the government to establish maximum sodium levels for different foods, though the FDA said then it favors a voluntary route.

Americans eat about 1½ teaspoons of salt daily, about a third more than the government recommends for good health and enough to increase the risk of high blood pressure, strokes and other problems. Most of that sodium is hidden inside common processed foods and restaurant meals.

In addition to flavor, companies use sodium to increase shelf life, prevent the growth of bacteria, or improve texture and appearance. That makes it more difficult to remove from some products, Hamburg noted.

Once the guidelines are issued, Americans won’t notice an immediate taste difference in higher-sodium foods like pizza, pasta, bread and soups. The idea would be to encourage gradual change so consumers’ taste buds can adjust, and to give the companies time to develop lower-sodium foods.

“I think one of the things we are very mindful of is that we need to have a realistic timeline,” Hamburg said.

Health groups would prefer mandatory standards, but say voluntary guidelines are a good first step.

Still, Michael Jacobson of the Center for Science in the Public Interest says he is concerned companies may hesitate, worried their competitors won’t lower sodium in their products.