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Is salt bad for you? Here’s why scientists can’t agree

Todd Hartley writer headshot By | Updated on April 2, 2020
Medically reviewed by Anis Rehman, MD

When it comes to sodium chloride, better known as salt, there’s one thing all scientists and doctors agree on: Your body needs some amount of it. Sodium helps regulate the body’s fluid levels and blood pressure and is essential for muscle and nerve function. 

But when it comes to how much sodium we need—or, more importantly, how much sodium is too much—that’s where the disagreements begin. Health organizations have linked excess sodium intake to cardiovascular problems like high blood pressure, heart disease, and increased risk for heart attacks and strokes, but many doctors think that most people are fine consuming salt and actually need it for a healthy lifestyle. People with kidney disease are thought to have improvement if they avoid excessive salt intake. So which is it, and why is the medical community split on the answer?

Is salt good or bad for you?

You’ve probably heard or read somewhere that eating too much salt is bad for you. In fact, there have been thousands of articles written on that exact subject, but those articles haven’t always examined the full scope of the relationship between salt intake and heart health. A 2016 study by Columbia University and Boston University, cited in Science Daily, looked at 269 salt-intake-related academic papers written between 1979 and 2014 and found that there was deep disagreement among the authors. The study judged whether each paper “supported or refuted the link between reduced sodium intake and lower rates of heart disease, stroke, and death” and found that 54% supported the idea, 33% refuted the idea, and 13% were inconclusive. They also found that the papers’ authors on either side of the issue were “more likely to cite reports that drew a similar conclusion than to cite reports drawing a different conclusion.” This calls into question how trustworthy the papers really were.

The truth is that salt is both good and bad for you. Keeping a healthy amount of sodium in your system is essential for life, but having too much or too little can be dangerous and lead to long-term health problems. The American Heart Association (AHA) recommends “no more than 2,300 milligrams a day and moving toward an ideal limit of no more than 1,500 mg per day for most adults.” 

The problem is that Americans eat, on average, 3,400 mg of sodium per day. That’s more than twice as much sodium as the AHA recommends. We cook salty meals and usually add more salt to them when they arrive at the table. Processed and prepared foods can be even higher in sodium. For most people, it can seem unrealistic to maintain a rate of 2,300 mg of sodium a day—much less 1,500 mg. Still, it can be done with a limited diet and careful monitoring of salt intake, but is it worth it?

The health benefits of salt

Sodium is an electrolyte, which is a mineral that can carry an electric charge when it’s dissolved in a liquid like blood. As such, it serves an important role in the cardiovascular system and the body’s metabolism. Sodium helps the body maintain normal fluid levels and plays a key role in nerve and muscle function. People used to believe that consuming more salt would make you thirstier, but a 2017 study in the Journal of Clinical Investigation found that eating more salt actually led to increased body water conservation, making people less thirty. Many doctors take this to mean that, given enough salt and water, the body is capable of choosing its preferred level of sodium.   

According to the AHA, our bodies can operate just fine on less than 500 mg of sodium per day. That’s less than one quarter of a teaspoon of salt. But that doesn’t necessarily mean that a low-salt diet is better for you than a regular diet. Studies have shown that diets that are in the middle ranges salt-wise—those considered low usual, usual, and high usual sodium intakes—don’t show a significant difference in overall health outcomes for most people. Diets considered low sodium intake, on the other hand, can be nearly as unhealthy as those that are high in sodium.

Sources of sodium intake

More than 70% of the average American’s sodium intake comes through packaged, prepared, and restaurant foods. The rest is mostly the kind you’re sprinkling on by yourself, and it comes in a wide array of choices. There’s kosher salt, sea salt, table salt, iodized salt, pink salt, even Hawaiian salt and Himalayan salt. They’re all about the same when it comes to nutritional values, with the exception of iodized salt.

“What we do in the U.S. and a lot of places in the world is put iodine in the salt,” says Kristy Bates, a registered nutritionist-dietitian with Aspen Valley Hospital in Colorado. She says that’s a good thing because iodine helps prevent hypothyroidism, which leads to goiter (an abnormal enlargement of the thyroid gland). In several parts of the world, iodine is deficient from the diet, therefore, iodine is mixed with the edible salt to avoid iodine deficiency. 

If you want to put the salt shaker away and don’t like packaged or prepared foods, you can eat healthy and still get enough sodium through sources like meats, shellfish, beets, celery, carrots, cantaloupe, spinach, chard, artichokes, and seaweed. Good liquid sources of sodium include milk and coconut water. Sports drinks tend to overdo things with the sodium and sugar, according to Bates, so she had a tip for weekend warriors rehydrating that way.

“One bottle of sports drink you can actually stretch into three,” she said. “The more optimal formula for electrolyte replenishment would be a third of what’s in a sports drink bottle. So split it up, and you can get three for the price of one.”

The health risks of salt

Most doctors recommend that most people get less sodium in their diets. High sodium levels in the blood can cause inflammation, which, over time, can put you at risk for a number of serious health problems, including high blood pressure, stomach cancer, kidney stones, headaches, osteoporosis, stroke, and heart failure.   

“Inflammation is kind of a silent killer,” Bates says. “You don’t necessarily realize that you’re inflamed. It’s not necessarily painful, so it can go on for 20 years, and you won’t realize it until your blood vessels are compromised.”

What happens when you have too much salt?

Hypernatremia—too much sodium in the blood—is essentially the same as dehydration, when there is too little water in the body. In acute cases it’s usually not caused by eating too much salt. Instead, it can be brought on by not drinking enough water, severe diarrhea, vomiting, fever, kidney disease, diabetes insipidus (loss of water hormone), certain medications, and large burn areas on the skin.

Symptoms of hypernatremia include:

  • Thirst
  • Frequent urination
  • Water retention, or weight gain
  • Puffiness, swelling, or bloating
  • Frequent headaches

In addition to those symptoms, over time too much sodium can cause your taste buds to be less sensitive, meaning food loses its flavor, meaning you’re likely to add more salt to it to make it taste better. It can be a bit of a snowball effect that can be countered by taking steps to eat a low-sodium diet. Although they may not be necessary for everyone, diets that restrict sodium intake to less than 2,300 mg per day (about a teaspoon of salt) are often prescribed for people with certain medical conditions like high blood pressure, kidney disease, and heart failure. Lower sodium levels can also help make those people’s medications more effective. 

What happens when you don’t have enough sodium in your diet?

Hyponatremia—too little sodium in the blood—is a relatively rare condition that can be caused by certain medications, problems with the heart, kidneys, or liver, hormonal changes, chronic alcoholism, malnutrition, or just drinking too much water. This has been known to happen to athletes who over-hydrate when they aren’t sweating very much and people using illicit drugs, particularly MDMA, also known as ecstasy or molly.

Symptoms of hyponatremia include:

  • Fatigue
  • Nausea and vomiting
  • Muscle weakness, cramps, or spasms
  • Confusion, restlessness, or irritability
  • Seizures

Mild, chronic hyponatremia can go undetected and may not cause any noticeable symptoms, but it may contribute to higher levels of cholesterol and triglycerides (a type of fat) in the blood. Acute hyponatremia, when sodium levels drop rapidly, can lead to brain swelling, seizure, coma, and even death. The condition can often be prevented by treating any underlying medical conditions that can cause hyponatremia, or by drinking water in moderation or fluids that contain electrolytes when engaged in physical activities or sports. 

Who should follow a low-sodium diet?

Many people are salt-resistant, meaning the amount of sodium in their diet does little to change their blood pressure. Others, who are salt-sensitive, can see their blood pressure rise by five points or more if they go on a high-sodium diet. For these people, who usually have high blood pressure to begin with, a low-sodium diet can be important for overall health. Low-sodium diets can also help people trying to lose weight, as high sodium levels cause the body to retain water, which can contribute to weight gain.

To follow a low-sodium diet, be sure to read nutritional information labels carefully and select items that are low in salt. Put away the salt shaker and season your food with other spices. Avoid packaged or prepared foods. Don’t eat out at restaurants very often, and especially avoid the AHA’s “Salty Six:” breads, cold cuts, pizza, poultry, soup, and sandwiches. 

How much salt a day is safe?

For those who don’t have high blood pressure, there’s evidence that the amount of salt you consume does little to affect your blood pressure and other health markers. That being said, there’s also evidence that consuming less sodium is a smarter strategy in the long term. Essentially, though, unless the amount of sodium in your blood is causing problems, any amount between 500 mg and 3,400 mg per day is likely safe. A better idea, however, would be to try to stay within the AHA’s guidelines of 1,500 mg to 2,300 mg per day. That’s a range that most doctors and scientists would agree on.