Some people were directed by their doctors to lose the sodium; others could go ahead and eat salty dill pickles washed down with equally salty tomato juice. Now, thankfully, science has come up with a game plan for everyone.
Scientists themselves have been hotly divided on the issue for many years. Many believed that the best research showed a compelling connection between high salt--or, to be more accurate, high sodium--intake and high blood pressure; they recommended that some, if not all, people with high blood pressure restrict the amount of sodium in their diets. Other scientists, however, pointed to a countless number of studies published in the mid-1990s that indicated restricting sodium had only a minimal effect on blood pressure, at best.
(Remember, the more sodium in your blood, the more your blood volume increases--sodium attracts and holds on to water. As a result, your heart has to work harder to move the increased volume of blood through your blood vessels. The result? Increased pressure on your arteries.)
Then, early in 2001, came the results of a second DASH study. This study--dubbed DASH II--was conducted to look specifically at what would happen to blood pressure levels when people followed different diets with different levels of sodium. (In other words, the study was designed to try and end the "to salt or not to salt" debate once and for all.) The first DASH study hadn’t tested salt reduction.
The 412 participants in DASH II were randomly assigned to eat either a "typical" American diet or the DASH diet. (To ensure against "cheating," all food was provided.) The people in both groups ate a high level of salt (3,300 milligrams a day--about the average American intake) for one month, a medium level (2,400 milligrams a day--the maximum recommended by the American Heart Association and other health organizations) for a second month, and a low level (1,500 milligrams a day) for a final, third month. About 40 percent of the study's participants had high blood pressure (blood pressure over 140/90 mm Hg); the rest had "high normal" blood pressure.
Low sodium, lower pressure. The study's results were astounding. They clearly showed that eating less sodium significantly lowers blood pressure--as much as taking a single blood pressure medication. The people in the study who consumed the least amount of salt--1,500 milligrams a day--experienced the most dramatic decrease in BP: an average drop of 8.9 mm Hg in systolic pressure and of 4.5 mm Hg in diastolic pressure.
"Prior to our study, some experts had questioned whether it was worthwhile for people without high blood pressure to cut back on their salt intake," said Lawrence J. Appel, M.D., an associate professor of medicine at Johns Hopkins University and one of the principal authors of the study. "This study settles this controversy and further emphasizes the powerful effects of dietary change on blood pressure."
In fact, according to the National Heart, Lung, and Blood Institute, if Americans limited their salt intake to less than 1 teaspoon a day, strokes could be reduced by 42 percent and heart disease by more than 20 percent.
Do You Have a Salt Tooth?
So how much salt (sodium chloride) should you be eating? To begin with, you should know that your current diet is probably way too salty. You need no more than 200 to 500 milligrams of sodium a day--about the amount in 1/2 teaspoon of salt. Because sodium is found naturally in whole foods, from apples to broccoli to rice, you can easily get enough of it without ever picking up a salt-shaker. And that's a good thing, because your body uses sodium to maintain fluid balance, transmit nerve impulses, and regulate your blood pressure.
But if you're like most Americans, you consume 8 to 10 times more salt than you need--a total of 4,000 to 6,000 milligrams a day. Measured in teaspoons, that's 2 to 3 a day.
Ah, you say, but you never salt your food, either when cooking or at the table. Well, that's a good start. But salt-shakers account for only about 15 percent of the salt that lands in our food. The vast majority--nearly three-quarters--of the salt we ingest arrives "hidden" in processed foods. Canned vegetables and soups. Frozen dinners. Cheese. Pretzels. Potato chips. Cookies. Cakes. Breads. Breakfast cereals. Soft drinks. The list goes on and on.
Some processed and convenience foods are so highly salt ed, they deliver more than 1,000 milligrams of sodium in a single serving. One cup--just one--of many canned soups, for example, has well in excess of 1,000 milligrams. So does one deluxe fast-food burger, a couple of pieces of most pizzas, and several fried chicken breasts.
In general, the less processed the food, the less sodium is contained in it. One cup of whole-wheat flour, for example, contains 6 milligrams of sodium; a slice of whole-wheat bread contains 148 milligrams. A whole fresh peach contains 0 milligrams sodium; a piece of peach pie contains 253 milligrams.
Shed the saltshaker for good? Before DASH II, most experts recommended that people with high blood pressure consume no more than 2,400 milligrams of sodium a day (about 1 teaspoon). They also thought that only certain people with high blood pressure--perhaps half--were "salt sensitive," or likely to see their blood pressure drop if they cut back on salt. So they recommended that people cut back on their salt for a few weeks to see if doing so had any impact on their blood pressure. If the pressure dropped, the people were told to stay on a salt-restricted diet; if the pressure stayed the same, they were told not to bother.
Since DASH II, however, many experts are rethinking that game plan. The study showed that the more you cut back on salt, the greater the drop in blood pressure. So although restricting sodium to 2,400 milligrams a day is okay, limiting it to 1,500 milligrams appears to be even better. Furthermore, although the study confirmed that some groups of people--especially African Americans and women--benefited the most from reducing the salt in their diets, every group, including young adults and even people without high blood pressure, saw their blood pressure go down when on a salt-restricted diet.
If you have high or even high normal blood pressure, you will probably benefit from eating less salt. How much you want to lower your salt intake is up to you and your doctor, but most experts agree that you should try to get it down to under 2,400 milligrams a day, at the very least. Fortunately, salt, like sugar, is an acquired taste. The less you eat of it, the less you'll crave it.
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