Jan. 3, 2001 -- Almost fifty million people in the U.S. suffer from high blood pressure, and most everyone knows that blood pressure is related to sodium, or salt intake. So what's the latest news in the fight against high blood pressure?
Cutting back on salt helps lower blood pressure regardless of age, sex, race, or dietary patterns, according to a new study. This beneficial result occurred in people who ate a standard U.S. diet or an especially healthy diet designed to reduce blood pressure.
"This study has shown conclusively that in both individuals with hypertension, and those without hypertension, lower dietary sodium levels lower blood pressure," William M. Vollmer, PhD, tells WebMD. Vollmer is co-author of the study and a senior investigator at the Kaiser Permanente Center for Health Research in Portland, Ore.
The study, published in the Jan. 4, 2000 issue of The New England Journal of Medicine, looked at more than 400 people, 160 of whom had high blood pressure. For 14 weeks, all their food was provided by the researchers. Some ate a typical U.S. diet, while some ate what's called the DASH diet, or Dietary Approaches to Stop Hypertension. This diet is high in fruits, vegetables and low-fat dairy products, and includes whole grains, poultry fish and nuts. It limits red meat, sweets, and fats, especially saturated fat.
People in both groups ate a low level of salt for 30 days, a medium level for 30 days, and a higher level for 30 days. What was found for all groups -- women and men, those who had high blood pressure and those who didn't -- was that the lower the salt intake, the lower the blood pressure, which ultimately means fewer heart attacks and strokes down the road.
"We used to think only about a third of people were salt-sensitive, but this study shows that's not the case," Susan West, MD, tells WebMD. "It is very well done, very convincing. Salt restriction is definitely worthwhile. I suggest that all my patients should watch their sodium intake." West, who was not involved in the study, is an assistant clinical professor of medicine at Jefferson Medical College in Philadelphia.
Studies show U.S. adults eat 3,300 mg of sodium per day on average. That's the "high" level used in this study. Current government standards recommend 2,400 mg a day, the medium level studied. However, the researchers found continued benefits when people ate only 1,500 mg of sodium per day, well below currently recommended levels.
One teaspoon of salt contains 2,300 mg of sodium. However, that last sprinkle of salt isn't the real problem, Vollmer says. Processed foods are the greatest source of sodium in the American diet, and most of this sodium is hidden. People don't even realize how much salt they're eating. "The best way to lower salt intake is to buy fewer processed foods," he says. "This has the added advantage that it will also lower sugar and fat intake, since processed foods also tend to be high in those ingredients as well."
He's also concerned about possible pressure to remove sodium content from the labels of processed foods, since this labeling is essential in aiding consumers to choose foods wisely.
"Fast food restaurants are one of the greatest contributors to a high-salt diet," Joanne Keaveney, RD, tells WebMD. "If you currently go there once a week, try to cut down to once a month. You can get above the recommended daily intake just by having a large hamburger and fries for lunch." Keaveney is a dietician at Harvard Vanguard Medical Associates, in Boston.
She warns that other foods high in sodium include frozen dinners, olives, cheese, and canned soups. "Chinese food is very high in salt, too, and many people don't realize this," she says. "They say 'hold the MSG' and think they've solved the problem, but the meal is still loaded with sodium."
The more fresh foods you buy, she says, the healthier you'll be. "People get in trouble because they stop off to get a fast-food sausage and biscuit on the way to work -- that's already 2,000 mg of salt. Suppose you got a bagel instead? ... That's only 50 mg. Or eat a cut-up apple and granola -- that's still under 100."