You are here:

Salt shakedown: A boon for lowering blood pressure

New guidelines to reduce added sodium in food are good news for everyone—not just people with high blood pressure.

cold cuts sodium salt blood pressure
Image: rezart/iStock

If you’re like most people, chances are you eat far more than the recommended amount of sodium, one of the main components of salt. But cutting back may be a little easier in the future, thanks to the FDA’s recent proposed guidelines to scale down sodium levels in processed and restaurant food.

Health experts consider the move a long-awaited step in the right direction. Strong evidence from more than 100 clinical trials shows that lowering dietary sodium also lowers blood pressure. High blood pressure (hypertension), which affects one in three American adults, is a key culprit in cardiovascular disease.

“I’m glad to see the FDA is finally doing something, and the gradual reduction they’re proposing is the way to go,” says Dr. Nancy Cook, professor of medicine at Harvard Medical School. Public health authorities, nutritionists, and cardiologists have been urging the agency to do something to regulate high sodium levels in our food supply for decades, she notes. A gradual reduction gives food companies time to reformulate their products and consumers time to adjust their taste buds.

Sodium sources

Current federal guidelines advise getting no more than 2,300 milligrams (mg) of sodium daily, but the average American consumes about 3,500 mg a day. Most of it—about 75%—comes from processed and restaurant foods, not the salt shaker. In the United States, the top sources of dietary sodium are breads and rolls (mostly because people eat these foods often); cold cuts and cured meats; pizza; poultry dishes (such as rotisserie chicken and chicken nuggets); soup; and sandwiches (including burgers).

A salty diet spills excess sodium into your bloodstream. This signals your kidneys to hold on to more water, and the extra fluid causes blood pressure to rise. But even in people without high blood pressure, excess sodium may harm the heart, kidneys, brain, and blood vessels.

According to a 2010 analysis in The New England Journal of Medicine, trimming sodium from our food supply could save many lives—and a lot of money. The projected annual benefits from slashing the average person’s sodium intake by about 1,200 mg a day include

  • preventing as many as 99,000 heart attacks and 66,000 strokes
  • reducing the number of deaths from any cause by as many as 92,000
  • saving up to $24 billion in health care expenses.

A possible paradox?

These benefits have been questioned, however, based on a few studies that suggest a paradoxical link between low sodium and a higher risk of cardiovascular disease. But those studies have fundamental flaws, notes Dr. Cook. For example, the observations are based on one-time “spot urine” tests to estimate sodium intake, which isn’t considered an accurate measure. Also, one recent study that pooled data from 49 different countries included some people with pre-existing disease and poor diet quality.

Clinical trials provide more reliable results. For example, the Trials of Hypertension Prevention (TOHP), which began in 1987, compared two groups of people at risk for high blood pressure. Half got advice and support to help lower their daily sodium intake to 1,800 mg; the other half had no sodium restrictions. During the two-phase trial, which lasted up to three years, the investigators estimated the participants’ sodium levels from multiple 24-hour urine measurements.

As expected, people who met the lower sodium goals had lower blood pressure compared with the controls. After the study ended, they didn’t necessarily stick to a strict low-salt diet, although many tended to choose less salty foods. Dr. Cook found that compared with the control group, those in the low-sodium group were 25% less likely to develop heart disease in the next 10 to 15 years. And results from the 20-year follow-up (which Dr. Cook presented at last year’s American Heart Association meeting) showed that they had a 15% lower risk of dying from any cause during that period.

The TOHP participants all had “prehypertension,” which is defined as a blood pressure reading of 120/80 to 139/89 millimeters of mercury (mm Hg). At least half of the population falls into this category, says Dr. Cook.

The FDA’s short-term target to lower our average sodium intake to about 3,000 mg per day may not make a dramatic difference in preventing and treating high blood pressure. But it’s a start—and will likely be easy to swallow, says Dr. Cook. “Because of all the research I’ve done, I try to avoid eating too much salt. Now, if I have pretzels with a lot of salt, I notice. Once you cut down, your taste for salt really does change,” says Dr. Cook.

Posted by: Dr.Health

Back to Top