If your blood pressure is fine, is there still reason to be concerned about salt? Most people, after all, are not even "salt-sensitive"—that is, salt has little or no effect on their blood pressure. The short answer is yes, too much salt is bad for you.
In population studies, diets high in sodium (a component of salt) have been linked to an increased risk of hypertension—and hypertension, of course, can lead to heart attacks and strokes. But some research suggests that a high sodium intake may increase the risk of cardiovascular problems independent of its effect on blood pressure. Too much sodium can make blood vessels less flexible, which may cause or worsen atherosclerosis (hardening of the arteries).
In fact, a recent study in the American Journal of Clinical Nutrition found that a single high-salt meal (with about 1,500 milligrams of sodium) reduced the ability of blood vessels to dilate in healthy people within 30 minutes, even though blood pressure was not affected. A high sodium load can even trigger heart failure in people with impaired heart function. It’s all bad news for salt lovers.
Other Risks from Sodium:
Bad for Your Bones
The complex system that regulates blood pressure and fluid balance in the body may also be involved in bone health. A high sodium intake increases excretion of calcium in the urine, which causes calcium to be leached from bone, contributing to bone loss and increased risk of fractures over time. Studies have shown that reducing salt has a positive effect on calcium balance—and this may help slow age-related bone loss.
Bad for Your Kidneys
Salt contributes to hypertension in many people, and hypertension is a major cause of kidney dysfunction and failure. There is evidence from animal and some human studies that salt may directly impair kidney function in some people, too. By increasing calcium in the urine, a high sodium intake may also increase the risk of kidney stones.
Bad for Your Stomach
Some studies have linked a high salt intake to cancers of the stomach, colon, and rectum, as well as to stomach ulcers. Though the evidence is not clear, salty foods may affect the stomach lining, making it more likely that the bacterium H. pylori—a major cause of ulcers and stomach cancer—can infect tissues. It’s theorized that a salty stomach environment may also alter the structure of H. pylori, increasing its ability to survive and thus do more damage over time.
How Else Is Salt Bad for You?
It's proposed—but not proven—that a high sodium intake may contribute to inflammation in the body and worsen asthma. It can also damage blood vessels that feed the brain, which can lead to vascular dementia. And there may be an indirect link between sodium and weight gain, since sodium can increase thirst, which often leads to the consumption of high-calorie beverages.
What You Gain by Cutting Back on Salt
Sodium is critical for maintaining basic body functions, including the regulation of fluid balance and the transmission of nerve impulses. But most Americans get far more sodium and salt than they need. Cutting back on sodium may reduce your risk of hypertension (and its deadly consequences) and have other potential health benefits as well.
What you also achieve is a better diet—salty foods tend to be high in calories and low in nutrients—and thus a lower risk of many diseases.
The U.S. Dietary Guidelines recommend limiting sodium to 1,500 milligrams a day if you are over 50, black, or have hypertension, diabetes, or chronic kidney disease (that’s most adults). The easiest way to do this is to limit processed, packaged, and restaurant foods.
Originally published in The University of California, Berkeley Wellness Letter (June 2011)