Most of the information on nutrition labels can help you stay healthy. Heeding one number in particular -- sodium levels -- just might save your life.
Salt, which is sodium chloride, has long been linked to high blood pressure. And high blood pressure, or hypertension, which afflicts nearly one in three Americans, is a leading cause of cardiovascular disease.
Blood pressure is the measure of the force of blood against artery walls. When it rises too high, the pressure causes damage to many organs, including heart, kidneys, brain, and even eyes. By 2025, predictions suggest, 60% of Americans will have high blood pressure.
Salt isn’t the only cause of high blood pressure. Lack of exercise, poor diets, and inherited risk also contribute. “But Americans consume way too much salt, mostly in processed foods,” said University of Pennsylvania nutrition expert Lisa Hark, author of Nutrition for Life. “Cutting back on high-sodium foods is one simple way to lower your risk.”
DASH Your Way to a Low Sodium Diet
In one landmark DASH experiment, volunteers were divided into three groups. One group consumed 3,300 milligrams of salt a day, about the average for most Americans. Another limited their intake to just 2,400 mg, which is what most experts recommend. The third cut back to only 1,500 mg a day. Across the spectrum, the less sodium the volunteers consumed, the lower their blood pressure.
“The results of the DASH-sodium study proved convincingly that cutting back on sodium even below recommended levels has impressive benefits,” said Christine A. Rosenbloom, PhD, RD, professor of nutrition at Georgia State University.
Other studies confirm the benefits of a low-sodium diet. In a 2003 report that pooled results from a variety of research trials around the world, scientists showed that reducing sodium intake by 1,000 mg a day lowers systolic blood pressure by an average of 4 mm Hg and diastolic blood pressure by 2.5 mm Hg in patients with hypertension. Easing off salt reduced blood pressure even in people with what’s considered normal pressure.
Low Salt, Low Sodium = Proven Health Benefits
The ultimate goal, of course, is reducing cardiovascular disease and other complications from hypertension. In a study published in 2007 in the British Medical Journal, researchers at Brigham and Women’s Hospital in Boston contacted volunteers who had taken part in two studies of low-sodium diets, one done in 1985 and the other in 1990.
“Our survey showed that many of the participants were still following low-sodium advice,” said epidemiologist Nancy Cook, ScD, who led the study. And Cook’s additional findings showed they were the healthier for it. The research team found that reducing sodium slashed cardiovascular disease by 25% to 30%.
The Potassium Connection
Not everyone is sensitive to the blood pressure effects of sodium. Most Americans consume more than the recommended amount of salt, yet the majority does not have high blood pressure. This suggests that other factors are also involved in hypertension risk. One culprit, researchers now believe, is lack of potassium.
Potassium deficiency causes cells to take up sodium. That, in turn, causes blood pressure to rise. When volunteers in several studies consumed their usual levels of sodium but cut back on potassium, blood pressure levels jumped by up to 7 points. When they increased their potassium intake, in contrast, blood pressure fell, even when the amount of sodium they consumed remained the same.
In the DASH trial, for example, volunteers who consumed the usual amount of salt -- but added servings of fruits and vegetables with potassium -- saw their blood pressure fall significantly.
Abundant sources of potassium include bananas, raisins, spinach, chard, milk, potatoes baked with the skin, lima beans, and prunes.
What to Look For on the Label
The most perilous combination, experts now say, is a high-salt, low-potassium diet. Unfortunately, that describes the diet that most Americans eat. You can use nutrition facts labels to help you reverse that trend.
The nutrition facts label prominently displays sodium, including both the milligrams contained in a serving and how much of your daily value that amount represents. Foods that have 5% of the daily value or less are considered low in sodium. Those with 20% or more are considered high in sodium.
Keep in mind: the label calculates a daily value of 2,300 mg sodium. The DASH-Sodium study showed that cutting back further than that lowers hypertension risk. The less salt you consume, the more likely your blood pressure will remain out of the danger zone.
As for potassium, one of the simplest ways to get enough is shop in the produce section of your grocery store. Fruits and vegetables are the leading source of this crucial nutrient. Shopping in the produce aisle has another advantage: you don’t have to worry about reading labels.