Does Salt Affect Blood Pressure and Health? : Part 2

by Food and Drug Administration (FDA)

(Page 2 of 2)

For Americans today, eating preserved and processed foods has become a way of life. According to Regina Hildwine, technical regulatory affairs, the National Food Processors Association, Washington, D.C., it is almost impossible to prepare a meal without using some processed food. Besides, not only is salt one of the four taste categories — salty, sweet, sour, and bitter — salt offers certain technical advantages in the kitchen. Two examples: It raises the boiling point of water, which helps heat penetrate into cooking foods, and it helps condition dough in baked products. And, adds Richard Hanneman, the biggest advantage of using salt is that it enhances other flavors.

But some scientists are concerned about the amount of salt in processed foods. "Seventy-five percent of the sodium consumed is in processed foods," says Anderson. "What the food industry includes during processing, we can't take out."

Stamler agrees. "If we reduce our salt intake [at the table]," he says, "that won't solve the problem. There's salt in bread, processed meat, cheese, canned vegetables — these are all hidden sources of salt." Fortunately, FDA's food labeling helps consumers monitor their sodium intake in processed foods. But, says Anderson, in restaurant foods, and that includes fast-food chains and Chinese restaurants, the "sodium levels can be very high."

New regulations that went into effect in May 1997 offer consumers some help with restaurant fare. The regulations apply the Nutrition Labeling and Education Act (NLEA) of 1990 to restaurant menu items that carry a claim about the food's nutritional content or health benefits.

Scientists Look at Salt

Scientists' suspicions about salt are not new. As Jeffrey Cutler, M.D., director of the Clinical Applications and Prevention Program, National Heart, Lung, and Blood Institute, points out, physicians in China back in 2,500 B.C. warned patients that if they used too much salt in their food, their "pulse" would harden.

"And since then," says Cutler, "scientists have refined that conclusion and there is scientific support for it. We have learned to measure blood pressure better than measuring the pulse and to quantify salt intake, and we have learned all the scientific experimental designs to study salt intake. The conclusion is still there. The higher the salt intake, the higher the prevalence of hypertension." Higher-than-normal blood pressure may lead to heart attacks, kidney disease, and strokes.

Cutler estimates that persistent high blood pressure — conventionally defined as readings of 140/90 or above — is one of the most common health conditions, affecting nearly 50 million Americans. People at greatest risk for high blood pressure are those with a family history, the elderly, middle-aged men, and middle-aged Black women.

Yet everyone is vulnerable, says Stamler, because blood pressure normally rises with age, a fact corroborated by numerous studies, and high-salt intake contributes to that rise. "The fundamental conclusion is that salt relates to high blood pressure independent of other factors affecting blood pressure, like alcohol and obesity," he says. "There is such a massive body of evidence," he adds, including the 1988 Surgeon General's report on nutrition, the National Academy of Sciences' report on diet and health, and the Intersalt research group.

We don't know exactly how salt works to elevate blood pressure, says Anderson. But the best guess is that too much salt causes the sodium channels (structures that move sodium into and out of cells) to work too hard and gradually the channels begin to fail. This process is irreversible, so that by old age, even if people cut back on salt, their kidneys can no longer flush extra amounts of salt from the body without an increase in blood pressure.

Salt may also be linked to other health problems. "One of the aspects of salt that has been neglected," says Stamler, "is the growing evidence that high-salt intake is bad news for other problems ... such as aggravating asthma, gastric cancer, kidney stones, osteoporosis ... a wide range of problems."

Regulating Salt Intake

FDA is not advising people on how high or low their salt intake should be, says Ida Yoder, a chemist with FDA's over-the-counter drug products division. "By appropriate labeling, we are attempting to inform the public and those who want to keep their sodium intake down as to the amount of sodium they are consuming. The sodium labeling regulations for both foods and over-the-counter drugs require sodium content labeling for those products that contain a certain amount of sodium."

Following a salt-restricted diet will, for many people, be what the doctor orders. And while many people say they crave salt and use it liberally in their food, restricting salt intake is only really a matter of making some adjustments, says Anderson. "If people make a concerted effort to reduce salt intake," she says, "initially they notice that things don't taste salty enough. But if they go through a transition period and then go back to foods they used to like, they find them too salty."

In the end, wise consumers will choose diets of moderation in all things. The Dietary Guidelines, developed jointly by the U.S. Department of Health and Human Services and Department of Agriculture, stresses just that when discussing daily needs for salt, pointing out that eating less salt is not harmful and can be recommended for the healthy normal adult.

Tips on Reducing Salt Intake

Alicia Moag-Stahlberg, a research nutritionist at Northwestern University Medical School in Chicago and spokeswoman for the American Dietetic Association, offers the following tips for those who want to reduce salt intake:

Take stock of the sources of salt in your diet, such as restaurant meals, salt-based condiments, and convenience foods. Some of these are really loaded with salt.

Read the labels when shopping. Look for lower sodium in cereals, crackers, pasta sauces, canned vegetables, or any foods with low-salt options.

If you think your meals are high in sodium, balance them by adding high-potassium foods, such as fresh fruits and vegetables.

Ask about salt added to food, especially at restaurants. Most restaurant chefs will omit salt when requested.

If you need to salt while cooking, add the salt at the end; you will need to add much less. The longer the food cooks, the more the salty flavor is muted and at the end, the final taste is on the top layer.

About the Author

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FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.