The Salt Breakthrough
HOW MUCH SALT IS TOO MUCH? AND CAN TOO LITTLE RAISE YOUR BLOOD PRESSURE?
For years, we’ve been told that a high-sodium diet leads to high blood pressure. But is that really the case? New research from the University of Virginia says, “no.” In fact, a high-sodium diet may actually lower blood pressure in some people. Here’s a look at the latest research on salt, plus tips on how to ensure that you’re getting just the right amount of sodium for you.
Salt has a bad rap for raising blood pressure and risk for heart disease and stroke, but some studies have questioned the low-salt mantra. For example, the Framingham Offspring Study followed more than 2,600 men and women for 16 years and found that those who consumed less than 2,500 mg of sodium daily had higher blood pressure than those who consumed more. This flies in the face of limits recommended by the American Heart Association of 2,300 mg of sodium daily, and ideally no more than 1,500 mg daily for most older people. It’s become a muddled issue. Enter the Salt Sensitivity Study (saltstudy.com) at the University of Virginia in Charlottesville. An NIH-funded research project that’s been going on for the past 10 years, it’s shedding some new light on the salt scene.
“A low-salt diet may not be beneficial to everyone and may paradoxically increase blood pressure in some individuals,” says the study’s principal investigator, Robin Felder, PhD. Bottom line: Each of us has a unique sweet spot for salt intake, called a “personal salt index” by the researchers, and your health risks will be lowest if you eat the right amount—not much more or less than your optimum amount.
How likely are you to need more or less salt? Initial testing in the Salt Study has found three categories of reactions to salt:
* Sodium doesn’t affect blood pressure in 72 percent of people, described by researchers as “salt-resistant.” * A high-sodium diet raises blood pressure in 17 percent of people, described as “salt-sensitive,” and a low-sodium diet will lower their blood pressure.
* For 11 percent of people, described as “inverse salt-sensitive,” a low-sodium diet will actually raise blood pressure. Increasing sodium will lower blood pressure.
Which Type Are You?
There isn’t any medical test to find your personal salt index, but you can do this: eat a low-sodium diet for a week, and then a high-sodium diet for another week and measure your blood pressure along the way. For test purposes, low-sodium is no more than 400 mg daily and highsodium is 1,800–2,000 mg of sodium daily.
Here are some other clues from Felder: At a football game where people load up on beer and salty hot dogs and snacks at the start, the inverse saltsensitive will be the first wave of people to go to the bathroom because they quickly eliminate water and salt. The salt-resistant will go later in the game. And the salt-sensitive may not go at all until they get home.
If you eat an unusually salty meal and feel really bloated the next morning or notice a gain of a few pounds on the bathroom scale, it’s water retention. You’re likely salt-sensitive.
How the Right Amount of Salt Keeps You Healthy
Elevated blood pressure readings during the daytime are only one possible sign of too much or too little sodium. Eating the right amount also plays a vital role in repairing arteries while you sleep, helping to prevent atherosclerosis, diabetes, and stroke.
“At night, our blood pressure is programmed genetically to drop about 10 percent and then come back up in the morning,” says Felder. “That 10-percent drop is the time when your body is repairing capillaries.”
By tracking blood pressure while people slept, the Salt Study found that the wrong amount of salt is harmful because it interferes with the normal nighttime drop. “At night,” says Felder, “if you aren’t dipping, you aren’t repairing.”