Cutting salt could save hundreds of thousands of lives, study says

Steadily reducing sodium in the foods we buy and eat could save a half-million Americans from dying premature deaths over a decade, says a new study. And a more abrupt reduction to 2,200 milligrams per day--a 40% drop from current levels--could boost the tally of lives saved over 10 years to 850,000, researchers have projected.

The new estimates, published Tuesday in the American Heart Assn.’s journal Hypertension, are the results of three separate teams crunching the numbers at the request of the Centers for Disease Control and Prevention. Researchers from UC San Francisco, Harvard University’s School of Public Health and Simon Fraser University in Canada came at their estimates independently, but found that their results converged.

If the average daily sodium intake of Americans were to drop instantaneously to 1,500 milligrams per day--a steep drop to a level considered “ideal”--as many as 1.2 million premature deaths could be averted over the course of a decade, the teams agreed.

Americans currently consume about 3,600 milligrams of sodium daily--roughly 40% above the “slightly less ambitious” interim goal posited by the researchers--and much of that is hidden in processed foods such as soups, cereals, bread and soups. While the link between sodium intake and high blood pressure is much debated, research strongly suggests that high-sodium diets can push blood pressure above safe limits and exacerbate high blood pressure, and that lowering sodium consumption tends to lower blood pressure. That’s important, because some 45% of cardiovascular disease in the United States is attributed to high blood pressure.

The researchers called efforts to reduce average American sodium intake by 40% “a daunting task that will likely require multiple layers of interventions.” Food industry experts and public health officials have been meeting in recent years to secure steady, small reductions in the sodium content of processed foods--reductions they believe that consumers might not even notice.

But even a small, steady reduction in average daily sodium consumption--the equivalent of 1/20th of a teaspoon of salt less each year--could avert 280,000 to 500,000 deaths per year, the researchers concluded.

How big of an effect would that be? If lower-salt diets could avert 500,000 deaths in the span of a decade, that would be like curing colorectal cancer, which claims just over 50,000 lives per year. It would be just a little less life-saving than preventing all annuals deaths in the United States attributed to influenza and pneumonia (about 53,000 in 2007). And it would be far more effective at reducing premature death than if the yearly number of automobile fatalities (almost 34,000) went to zero.

“No matter how we look at it, the story is the same--there will be huge benefits to reducing sodium,” says Pam Coxson, a UCSF mathematician who is the study’s lead author.