Time to cut back on salt (zt)

Tis the seaon: time to cut back on salt
FACULTY OF HARVARD MEDICAL SCHOOL

Q: I'm in my mid-40s and my blood pressure is a little high. Should I try to cut back on salt?

A: In general, eating less salt is a good idea. The average American consumes about 1.5 teaspoons of salt, or 3,400 milligrams (mg) of sodium, every day. That's a lot more than we actually need. But it turns out that salt affects people differently. How salt affects your blood pressure and health depends on your genes, your age and your medical conditions.

The white crystals we know as salt are made of sodium chloride, and it's the sodium that causes most of the problems. Some people are very sensitive to sodium. Their blood pressure rises and falls as a direct result of how much salt they get. Others don't seem to be affected at all. Unfortunately, there isn't an easy test to determine who is salt-sensitive.

Hundreds of studies have looked at the connections between salt intake and blood pressure, heart disease and stroke. Overall, they show that cutting back on salt lowers blood pressure and reduces the chances of having a heart attack or stroke.

Some of the best evidence that eating less salt can lower blood pressure comes from the Dietary Approaches to Stop Hypertension (DASH) trials. The first DASH trial showed that a diet rich in fruits, vegetables, low-fat dairy products, whole grains, beans, nuts, fish and poultry lowered blood pressure, both in people with normal and high blood pressures. A follow-up trial compared a DASH diet with a control diet that was much like the average American diet. Each test diet also had three levels of sodium: high sodium, at 3,500 mg of sodium a day; moderate sodium, 2,300 mg; and low sodium, 1,100 mg.

The DASH diet again proved better for blood pressure than the control diet. And across the board, the less sodium, the lower the systolic (the top number of a blood-pressure reading) and diastolic (the bottom number) pressures.

The low-sodium DASH diet worked best of all. Volunteers assigned to this combination had systolic blood pressure values that were 8.9 mm Hg (millimeters of mercury) lower than those on the high-sodium control diet, and their diastolic pressure was 4.5 mm Hg lower. In an individual, that's as beneficial as taking a medication to lower blood pressure.

There isn't a one-size-fits-all recommendation for daily sodium intake. Some people definitely benefit from getting less. For others, it won't make much of a difference on blood pressure.

Healthy people younger than 50 whose blood pressure is in the healthy range (under 120/80) have little reason to worry about dietary salt. But a lower-sodium diet is good for people who are older, who are of African American descent, who have high blood pressure or diabetes-- and for people (like you) whose blood pressure is gradually creeping upward. The Institute of Medicine, the Dietary Guidelines for Americans, and the American Heart Association call for all of us to limit our sodium intake to a maximum of 2,300-2,400 mg a day. But for people with high blood pressure and for everyone who is middle aged and older, the latest guidelines suggest a limit of 1,500 mg a day.

A surprisingly small amount of the salt we eat pours from the salt shaker, either in the kitchen or at the table. The bulk comes in processed foods. Luncheon meats, pasta sauce, canned and dried soup, even commercially prepared baked goods pack plenty of sodium (see sidebar). Here are a few basic tips for shaking your salt habit:

Read food labels and choose low-sodium products.

Limit the use of cured, canned and processed foods and frozen dinners.

When eating out, ask if items are prepared with salt.

In fast food restaurants, ask for a nutrition information sheet.

Cook with herbs and spices instead of salt.

Beware of snack foods, sauces, and condiments.

What about salt substitutes? Many are good, but others can be tricky, particularly for people with kidney disease and those who are taking medicines that boost their potassium levels. Keep in mind that sodium is just one of many factors that influence your blood pressure and heart health. For the greatest gains in both, a broader focus on healthful eating, exercise, weight control, tobacco avoidance, and stress reduction will have a bigger payoff.