We crave it. We love it. It’s not surprising why: salt makes food taste delectable. It helps keep food fresh and safe from spoilage. We also need salt. We literally can’t survive without sodium. Salt (a.k.a. sodium chloride) is our chief supply of this mineral, which helps our muscles contract, sends nerve impulses throughout our bodies and regulates fluid balance so we don’t become dehydrated.
But for more than four decades, health authorities have urged us to consume less salt. That’s because salt is roughly 40 percent sodium and too much of it can elevate blood pressure. In your body, sodium acts like a magnet for water, pulling fluid into your bloodstream. That excess liquid increases the pressure in your blood vessels and over time can damage their linings, potentially causing blood clots to form. Once those blood clots develop, they can eventually cause blockages that can lead to a heart attack or stroke.
Most of us eat about 3,400 milligrams of sodium a day. Downsizing our sodium intake to 1,500 milligrams daily would have major health benefits, slashing 16 million of the nation’s 68 million cases of hypertension and saving $26 billion health care dollars, according to the Centers for Disease Control. In 2004, the Institute of Medicine (IOM) agreed, advising anyone over age 50, of African-American descent or with high blood pressure, chronic kidney disease or diabetes to limit their sodium to 1,500 milligrams. That’s nearly half of all Americans. The rest of us were advised to keep our numbers below 2,300 milligrams, the amount in roughly a teaspoon of salt.
Then in May of 2013, in an apparent about-face, the IOM released a report concluding that too little sodium may be equally problematic for some people, particularly those with congestive heart failure. Even more startling, it announced there was no solid evidence that people with diabetes, kidney disease or cardiovascular disease would benefit from the previous 1,500-milligram cap and instead stated that 2,300 milligrams would be more appropriate. However, if you read the report’s fine print you’ll find that the IOM admits that the data used to make the updated 2013 recommendations contains gaps in its methodology. What’s more, shortly after its announcement, one of the main studies that the IOM report relied on was retracted by the journal Heart, leaving us more confused than ever.
Yet perhaps we’re missing the point. “By debating whether 1,500 or 2,300 is the magic number, we’re dancing on the head of a pin,” says Jane Henney, M.D., chair of a 2010 IOM Committee on Strategies to Reduce Sodium Intake in the United States. “We’re all eating so much more sodium than any of those numbers that if we can reduce our intake to between 1,500 and 2,300 milligrams a day we’d be a lot better off.”
Even if most Americans were interested in eating less sodium, whittling our intake down seems like a nearly impossible task. That’s because sodium saturates our food supply, occurring naturally in many foods but also lurking in foods that don’t even taste salty.
Your blood pressure isn't the only consideration when it comes to figuring out how much sodium you should be consuming. Here’s what to keep in mind:
—Karen Ansel, M.S., R.D., C.D.N.
Salt sensitivity, the likelihood that sodium will raise your blood pressure, increases with age. While slightly over a third of 45-year-olds have hypertension, that number jumps to more than half by age 55 and over 70 percent by age 75. Which is why after age 50 it’s more important than ever to keep an eye on your sodium intake.
"The blood vessels of people with diabetes are already stiffer, more brittle and more calcified, so they are more likely to experience the adverse effects of high blood pressure," says Elliott Antman, M.D., a professor of medicine at Harvard Medical School and president-elect of the American Heart Association. That makes prevention crucial. If you’re diabetic but don’t have high blood pressure, the American Diabetes Association recommends no more than 2,300 mg of sodium a day. If you have hypertension, limit yourself to 1,500 mg daily.
African-Americans are more likely to have high blood pressure than whites or Hispanics—and they develop it at an earlier age. They may carry a gene that causes extreme salt sensitivity. That’s why experts advise that African-Americans limit sodium to 1,500 mg a day. Forty-three percent of African-American men and 46 percent of African-American women have high blood pressure compared to 34 and 33 percent of all American men and women.
Because sodium holds on to fluid it helps you stay hydrated when you’re sweating up a storm. While that doesn’t usually mean you need extra sodium at mealtime, you might need a little more when you work out. If you break a sweat for an hour or longer, sip a sports drink during exercise to help fend off dehydration.
Keeping your salt intake in check can help prevent kidney disease. The reason: too much sodium can lead to high blood pressure, which is one of the most common causes of kidney disease. "If you already have kidney disease the stakes are even higher, especially since most people with kidney disease are salt sensitive," says Joseph A. Vassalotti, M.D., chief medical officer for the National Kidney Foundation. "The better your blood pressure control, the less likely you are to lose kidney function over time." According to a 2013 Journal of the American Society of Nephrology study, people with moderate to severe kidney disease who cut their sodium to between 1,380 and 1,840 mg daily for six weeks lowered their systolic and diastolic blood pressure by 10 and 4 points respectively. They also improved other markers of kidney disease.
Eating a high-sodium diet may also slowly weaken your bones. In a study in the Journal of Human Hypertension, for every additional 2,300 mg of sodium participants consumed daily, they excreted an extra 42 mg of calcium. That may not sound like much, but it’s the equivalent of losing an entire day’s worth of calcium each month, which, over time, could impact bone calcium levels. Here’s the good news: your body holds on to that calcium when you limit your daily sodium to less than 2,000 mg.
There are no specific sodium guidelines for kidney stones currently, so it’s unlikely your doctor is going to put you on a low-sodium diet. However, if you have had stones, watching your sodium may still make sense: consuming too much sodium doesn’t cause kidney stones directly, but because it ups the amount of calcium excreted, that can favor calcium stone formation, says Vassalotti.