Salt: How much is too much?

Salt is an edible rock that sustains life.

For generations, salt was essential to the preservation of food. Extracted from seawater or mined from mountains, it was traded for labor and taxed by tyrants. The tracks made by animals in search of salt licks formed the basis of our roads. Salt has created much of the world as we know it.

What’s remarkable is the transformation of salt, in the last half century, from icon of flavor to bogeyman.

Health research

Several reports over the past few years have demonstrated the lack of solid science supporting low-sodium diets. The New York Times recently reported that an expert committee commissioned by the Institute of Medicine at the request of the Centers for Disease Control and Prevention has issued a report saying there’s no good reason based on health outcomes for many Americans to drive their sodium consumption down to the very low levels (1,500 milligrams) recommended in national dietary guidelines.

Americans eat nearly twice the recommended amount of 1 teaspoon, or 2,300 milligrams, per day. Last year, the Canadian government revised its sodium intake recommendation upward, from 1,500 to 2,000 milligrams.

The U.S. Department of Agriculture, the Institute of Medicine, the Centers for Disease Control and the National Institutes of Health — the organizations advocating salt restriction today — all rely on the results from a 30-day trial of salt, which suggested that eating significantly less salt would lower blood pressure modestly. But “it said nothing about whether this would reduce hypertension, prevent heart disease or lengthen life,” writes Gary Taubes in the New York Times article, “Salt, we misjudged you.”

A study in Finland succeeded in lowering per-capita salt consumption but found that reduced salt consumption did not reduce mortality. The Mediterranean diet, much admired for its cardiovascular benefits, is actually very high in salt.

The authors of a recent report on sodium levels in fast food failed to note that in many countries (the Mediterranean region, Asia), salt consumption is higher than in the United States … but so is life expectancy and general health. Asian fish sauce and soy sauce, for instance, contain very high levels of sodium, but they don’t seem to be harmful or detrimental to longevity.

Harvard Medical School reports some people do need to watch their sodium intake much more closely than the general public, including people with hypertension, older adults and those with kidney problems.

Diets too low in sodium, in general, are dangerous. We need salt to keep our fluid balances in check. Some experts suggest eating less salt causes the kidneys to increase production of renin, which can increase the risk of heart disease. Several studies over the past few years have suggested “that reducing sodium to anything like what government policy refers to as a ‘safe upper limit’ is likely to do more harm than good,” writes Taubes.

Big Food’s role

“The salt shaker is not the culprit,” says Thomas A. Farley, New York City’s Health Commissioner. “Only about 10 percent of the sodium in our diet comes from salt we add to food while cooking or eating. Most of the salt we consume is already in food when we buy it. Foods that don’t even taste salty, like bread, are among the top sources of sodium in our diets.”

America’s salt intake primarily comes from manufactured, processed food, which contains hidden sodium in ingredients such as sodium benzoate (preservative), sodium caseinate (thickener), sodium nitrate (meat cure), sodium phosphate (emulsifier) and MSG, according to Salon.com. They commonly are used to extend shelf life and aren’t in fresh foods.

Michael Moss, author of “Salt Sugar Fat,” says brands such as Nestlé, Kraft, Nabisco, Unilever, General Mills, Procter & Gamble, Coca-Cola, PepsiCo, Mars and McDonald’s spend millions on research and development to figure out how to seduce American eaters — to get us addicted to the foods they create.

We consume half as much salt today as we did 75 years ago because refrigeration preserves food as it makes its way from the field to the table. But when Big Food gets involved in that food chain, it adds salt to stabilize and extend the shelf life of its products.

As always, follow your physician’s advice, which is likely to include avoiding processed foods laden with salt additives. It’s no reason for most of us to be afraid to cook or season with salt.

Ronald Holden is a food blogger at Cornichon.org who contributes to Crosscut.com, SeattleDining.com, EdibleSeattle.com and Eater.com.