Over the years, Americans have become inured to salt. Most people have no idea how much salt they consume on average, about 9 to 12 g (or 3,600 to 4,800 mg of sodium) per person per day, according to the American Heart Association (AHA). That's twice the amount recommended by the government.
In the past four decades, Americans' salt consumption has risen 50%, mostly as a result of eating more processed foods and more food prepared in restaurants. "Over time, we have adapted our taste buds and adapted our bodies to crave much, much higher levels of salt than we require to function," says Dr. Kirsten Bibbins-Domingo, an epidemiologist at the University of California, San Francisco. (See the top 10 food trends of 2008.)
Some salt is crucial for good health, of course to regulate blood pressure and assist with muscle and nerve function but too much (that is, at the levels we currently consume) can lead to hypertension, heart disease and stroke. If Americans halved their salt intake, as many as 150,000 premature deaths could be prevented each year, according to the American Medical Association. And new research presented March 11 by Bibbins-Domingo at the AHA's annual conference shows that even small reductions as little as 1 g of salt per day could have dramatic effects, saving 200,000 lives over the course of a decade.
Using a sophisticated computer model to analyze trends in heart disease over time among U.S. adults, Bibbins-Domingo and colleagues discovered that incremental population-wide reductions could drastically improve public health. Cutting out just 1 g of salt (or 400 mg of sodium) per person per day could prevent 30,000 cases of coronary heart disease across the U.S. population by 2019. Reducing consumption by half a more sizable 6 grams could prevent 1.4 million cases of heart disease during that same period. (See the top 10 medical breakthroughs of 2008.)
While eating less salt would improve the health of the population across the board, researchers found that the benefits would be greatest for African Americans and women. As a group, African Americans tend to have higher blood pressure than the general population, and "many studies suggest that they may be more sensitive to salt," Bibbins-Domingo says. Her analysis found that a reduction of 3 g of salt per day would reduce heart attacks 8% on average; among African Americans, that rate would drop 10%. A similar result was found in women, whose stroke risk dropped 8% with a 3-g reduction in salt intake; in men, the risk fell 5%.
The numbers certainly offer compelling incentives to cut salt consumption, but that's no easy task. You can put down the salt shaker and cut back on obviously salty snacks, but there's still so much sodium packed into processed foods that trying to extract it from your diet is a tricky business. "It's so pervasive in an average U.S. diet that it's really hard to tell people, 'You have to avoid salt,' " says Bibbins-Domingo.
And there is salt hiding in places you wouldn't think to look. According to a sodium chart from the U.S. Department of Agriculture, a single slice of commercially made whole-wheat bread has 148 mg of sodium; white bread has 170 mg. Cheerios contains 213 mg of sodium per cup; Total Raisin Bran, 239 mg. And then there are the big offenders: processed soups and sauces. Chicken noodle soup, for example, even after it has been diluted with water during preparation, has a whopping 1,106 mg of sodium per cup. "I think people don't have a clue," says Bibbins-Domingo. "The recommended daily amount of salt is about a teaspoon," she says. "It's easy to add that much if you're just adding salt," let alone all of the salt that's in food before we break out the shaker. (See pictures of what makes you eat more food.)
If you're dining out, all bets are off. According to the British organization Consensus Action on Salt in Health, a three-course meal in a restaurant can contain more than 15 g of salt, almost three times the recommended daily amount.
Bibbins-Domingo says it's especially tough for families with limited income, who tend to rely more on processed or packaged foods and canned fruits and vegetables rather than fresh foods. Patients tell her they've cut salted nuts, potato chips and pretzels from their diet and started eating more soup instead. "You realize that they're actually consuming more salt in their attempt to make healthy choices," she says.
Any large-scale success in salt-intake reduction would have to involve policymakers and the food industry, say public-health experts. "If you could reduce blood pressure by just a few points, you could reduce hundreds of thousands of deaths," says Dr. Thomas Frieden, commissioner of New York City's Department of Health and Mental Hygiene, who recently announced a national campaign to diminish salt intake 20% in the next five years and 40% in the next decade. Frieden, who has in the past targeted trans fats and led the charge to require chain restaurants to list calorie content on menus, has evoked less animosity from the food and restaurant industries with his desalinization efforts than with his previous initiatives.
"[Frieden] is looking for voluntary guidelines. It's a national movement, and he's working closely with the industry on developing these re-education guidelines," says Rob Bookman, an attorney for the New York State Restaurant Association, but he adds wryly, "I don't know if it's one big happy family." (See nine kid foods to avoid.)
Frieden points to a successful salt-reduction campaign in the U.K. as a kind of proof of principle. Several years after the British government launched an aggressive national campaign, which included voluntary reductions in salt content by food manufacturers, British citizens had reduced their annual sodium consumption roughly 10%. "If you look at what happened in the U.K., at first the industry was very concerned," Frieden says. "But after a few years, they saw that they could drop their salt content 20% to 30% [without losing customers]."
For Bibbins-Domingo, the issue is less about mandating food production or proscribing salt consumption than enabling people to make better choices. "This is actually something that we can achieve with very little cost to our personal liberties," she says.
But Frieden adheres to a harder line. When asked whether the government should be allowed to influence how or what we eat, he responded with a pointed rhetorical question: "Should industry be allowed to serve us food that makes us sick and kills us?"