Health organizations have been warning us about the dangers of salt for a long time.
That's because high salt intake has been claimed to cause a number of health problems, including high blood pressure and heart disease.
Photo credit: Shutterstock
However, decades of research have failed to provide convincing evidence to support this (1).
What's more, many studies actually show that eating too little salt can be harmful.
This article takes a detailed look at salt and its health effects.
What is Salt?
Salt is by far the biggest dietary source of sodium and the words “salt" and “sodium" are often used interchangeably.
The essential minerals in salt act as important electrolytes in the body. They help with fluid balance, nerve transmission and muscle function.
Some amount of salt is naturally found in most foods. It's also frequently added to foods in order to improve flavor.
Historically, salt was used to preserve food. High amounts can prevent growth of the bacteria that cause food to go bad.
Salt is harvested in two main ways: from salt mines and by evaporating sea water or other mineral-rich water.
There are actually many types of salt available. Common varieties include plain table salt, Himalayan pink salt and sea salt.
This is What Salt Looks Like:
Photo credit: Shutterstock
The different types of salt may vary in taste, texture and color. In the picture above, the salt on the left is more coarsely ground. The salt on the right is finely ground table salt.
In case you're wondering which type is the healthiest, the truth is that they are all quite similar.
Bottom Line: Salt is mainly composed of two minerals, sodium and chloride, which have various functions in the body. It is found naturally in most foods and is widely used to improve flavor.
How Does Salt Affect Heart Health?
This amounts to about one teaspoon or 6 grams of salt (salt is 40 percent sodium, so multiply sodium grams by 2.5).
However, about 90 percent of U.S. adults consume a lot more than that (7).
Eating too much salt is claimed to raise blood pressure, thereby increasing the risk of heart disease and stroke.
However, there are some serious doubts about the true benefits of sodium restriction.
It is true that reducing salt intake can lower blood pressure, especially in people with a medical condition called salt-sensitive hypertension (8).
But, for healthy individuals, the average reduction is very subtle.
One study from 2013 found that for individuals with normal blood pressure, restricting salt intake reduced systolic blood pressure by only 2.42 mmHg and diastolic blood pressure by only 1.00 mmHg (9).
That is like going from 130/75 mmHg to 128/74 mmHg. These are not exactly the impressive results you would hope to get from enduring a tasteless diet.
Bottom Line: Limiting salt intake does result in a slight reduction in blood pressure. However, there is no strong evidence linking reduced salt intake to a lower risk of heart attacks, strokes or death.
Low Salt Intake can be Harmful
There is some evidence suggesting that a low-salt diet can be downright harmful.
The negative health effects include:
- Elevated LDL cholesterol and triglycerides: Salt restriction has been linked to elevated LDL (the “bad") cholesterol and triglycerides (12).
- Heart disease: Several studies report that less than 3,000 mg of sodium per day is linked to an increased risk of dying from heart disease (13, 14, 15, 16).
- Heart failure: One analysis found that restricting salt intake increased the risk of dying for people with heart failure. The effect was staggering, with a 160 percent higher risk of death in individuals who reduced their salt intake (17).
- Insulin resistance: Some studies have reported that a low-salt diet may increase insulin resistance (18, 19, 20, 21).
- Type 2 diabetes: One study found that in type 2 diabetes patients, less sodium was associated with an increased risk of death (22).
Bottom Line: A low-salt diet has been linked to higher LDL and triglyceride levels and increased insulin resistance. It may increase the risk of death from heart disease, heart failure and type 2 diabetes.
High Salt Intake is Linked to Stomach Cancer
Stomach cancer, also known as gastric cancer, is the fifth most common cancer.
It is the third leading cause of cancer death worldwide and is responsible for more than 700,000 deaths each year (23).
A massive review article from 2012 looked at data from seven prospective studies, including a total of 268,718 participants (28).
It found that people with high salt intake have a 68 percent higher risk of stomach cancer, compared to those who have a low salt intake.
Exactly how or why this happens is not well understood, but several theories exist:
- Growth of bacteria: High salt intake may increase the growth of Helicobacter pylori, a bacteria that can lead to inflammation and gastric ulcers. This may increase the risk of stomach cancer (29, 30, 31).
- Damage to stomach lining: A diet high in salt may damage and inflame the stomach lining, thus exposing it to carcinogens (25, 31).
However, keep in mind that these are observational studies. They can not prove that high salt intake causes stomach cancer, only that the two are strongly associated.
Bottom Line: Several observational studies have linked high salt intake with an increased risk of stomach cancer. This may be caused by several factors.
Which Foods are High in Salt/Sodium?
In fact, it is estimated that about 75 percent of the salt in the U.S. diet comes from processed food. Only 25 percent of the intake occurs naturally in foods or is added during cooking or at the table (32).
There are also some seemingly un-salty foods that actually contain surprisingly high amounts of salt, including bread, cottage cheese and some breakfast cereals.
If you are trying to cut back, then food labels almost always list the sodium content.
Bottom Line: Foods that are high in salt include processed foods, such as salted snacks and instant soups. Less obvious foods, such as bread and cottage cheese, may also contain a lot of salt.
Should You Eat Less Salt?
However, if you are a healthy person who eats mostly whole, single ingredient foods, then there is probably no need for you to worry about your salt intake.
In this case, you can feel free to add salt during cooking or at the table in order to improve flavor.
Eating extremely high amounts of salt can be harmful, but eating too little may be just as bad for your health (16).
As is so often the case in nutrition, the optimal intake is somewhere between the two extremes.
This article was reposted from our media associate Authority Nutrition.
YOU MIGHT ALSO LIKE
By Lynne Peeples
Editor's note: This story is part of a nine-month investigation of drinking water contamination across the U.S. The series is supported by funding from the Park Foundation and Water Foundation. Read the launch story, "Thirsting for Solutions," here.
In late September 2020, officials in Wrangell, Alaska, warned residents who were elderly, pregnant or had health problems to avoid drinking the city's tap water — unless they could filter it on their own.
Unintended Consequences<p>Chemists first discovered disinfection by-products in treated drinking water in the 1970s. The trihalomethanes they found, they determined, had resulted from the reaction of chlorine with natural organic matter. Since then, scientists have identified more than 700 additional disinfection by-products. "And those only represent a portion. We still don't know half of them," says Richardson, whose lab has identified hundreds of disinfection by-products. </p>
What’s Regulated and What’s Not?<p>The U.S. Environmental Protection Agency (EPA) currently regulates 11 disinfection by-products — including a handful of trihalomethanes (THM) and haloacetic acids (HAA). While these represent only a small fraction of all disinfection by-products, EPA aims to use their presence to indicate the presence of other disinfection by-products. "The general idea is if you control THMs and HAAs, you implicitly or by default control everything else as well," says Korshin.</p><p>EPA also requires drinking water facilities to use techniques to reduce the concentration of organic materials before applying disinfectants, and regulates the quantity of disinfectants that systems use. These rules ultimately can help control levels of disinfection by-products in drinking water.</p>
Click the image for an interactive version of this chart on the Environmental Working Group website.<p>Still, some scientists and advocates argue that current regulations do not go far enough to protect the public. Many question whether the government is regulating the right disinfection by-products, and if water systems are doing enough to reduce disinfection by-products. EPA is now seeking public input as it considers potential revisions to regulations, including the possibility of regulating additional by-products. The agency held a <a href="https://www.epa.gov/dwsixyearreview/potential-revisions-microbial-and-disinfection-byproducts-rules" target="_blank">two-day public meeting</a> in October 2020 and plans to hold additional public meetings throughout 2021.</p><p>When EPA set regulations on disinfection by-products between the 1970s and early 2000s, the agency, as well as the scientific community, was primarily focused on by-products of reactions between organics and chlorine — historically the most common drinking water disinfectant. But the science has become increasingly clear that these chlorinated chemicals represent a fraction of the by-product problem.</p><p>For example, bromide or iodide can get caught up in the reaction, too. This is common where seawater penetrates a drinking water source. By itself, bromide is innocuous, says Korshin. "But it is extremely [reactive] with organics," he says. "As bromide levels increase with normal treatment, then concentrations of brominated disinfection by-products will increase quite rapidly."</p><p><a href="https://pubmed.ncbi.nlm.nih.gov/15487777/" target="_blank">Emerging</a> <a href="https://pubs.acs.org/doi/10.1021/acs.est.7b05440" target="_blank" rel="noopener noreferrer">data</a> indicate that brominated and iodinated by-products are potentially more harmful than the regulated by-products.</p><p>Almost half of the U.S. population lives within 50 miles of either the Atlantic or Pacific coasts, where saltwater intrusion can be a problem for drinking water supplies. "In the U.S., the rule of thumb is the closer to the sea, the more bromide you have," says Korshin, noting there are also places where bromide naturally leaches out from the soil. Still, some coastal areas tend to be spared. For example, the city of Seattle's water comes from the mountains, never making contact with seawater and tending to pick up minimal organic matter.</p><p>Hazardous disinfection by-products can also be an issue with desalination for drinking water. "As <a href="https://ensia.com/features/can-saltwater-quench-our-growing-thirst/" target="_blank" rel="noopener noreferrer">desalination</a> practices become more economical, then the issue of controlling bromide becomes quite important," adds Korshin.</p>
Other Hot Spots<p>Coastal areas represent just one type of hot spot for disinfection by-products. Agricultural regions tend to send organic matter — such as fertilizer and animal waste — into waterways. Areas with warmer climates generally have higher levels of natural organic matter. And nearly any urban area can be prone to stormwater runoff or combined sewer overflows, which can contain rainwater as well as untreated human waste, industrial wastewater, hazardous materials and organic debris. These events are especially common along the East Coast, notes Sydney Evans, a science analyst with the nonprofit Environmental Working Group (EWG, a collaborator on <a href="https://ensia.com/ensia-collections/troubled-waters/" target="_blank">this reporting project</a>).</p><p>The only drinking water sources that might be altogether free of disinfection by-products, suggests Richardson, are private wells that are not treated with disinfectants. She used to drink water from her own well. "It was always cold, coming from great depth through clay and granite," she says. "It was fabulous."</p><p>Today, Richardson gets her water from a city system that uses chloramine.</p>
Toxic Treadmill<p>Most community water systems in the U.S. use chlorine for disinfection in their treatment plant. Because disinfectants are needed to prevent bacteria growth as the water travels to the homes at the ends of the distribution lines, sometimes a second round of disinfection is also added in the pipes.</p><p>Here, systems usually opt for either chlorine or chloramine. "Chloramination is more long-lasting and does not form as many disinfection by-products through the system," says Steve Via, director of federal relations at the American Water Works Association. "Some studies show that chloramination may be more protective against organisms that inhabit biofilms such as Legionella."</p>
Alternative Approaches<p>When he moved to the U.S. from Germany, Prasse says he immediately noticed the bad taste of the water. "You can taste the chlorine here. That's not the case in Germany," he says.</p><p>In his home country, water systems use chlorine — if at all — at lower concentrations and at the very end of treatment. In the Netherlands, <a href="https://dwes.copernicus.org/articles/2/1/2009/dwes-2-1-2009.pdf" target="_blank">chlorine isn't used at all</a> as the risks are considered to outweigh the benefits, says Prasse. He notes the challenge in making a convincing connection between exposure to low concentrations of disinfection by-products and health effects, such as cancer, that can occur decades later. In contrast, exposure to a pathogen can make someone sick very quickly.</p><p>But many countries in Europe have not waited for proof and have taken a precautionary approach to reduce potential risk. The emphasis there is on alternative approaches for primary disinfection such as ozone or <a href="https://www.pbs.org/wgbh/nova/article/eco-friendly-way-disinfect-water-using-light/" target="_blank" rel="noopener noreferrer">ultraviolet light</a>. Reverse osmosis is among the "high-end" options, used to remove organic and inorganics from the water. While expensive, says Prasse, the method of forcing water through a semipermeable membrane is growing in popularity for systems that want to reuse wastewater for drinking water purposes.</p><p>Remucal notes that some treatment technologies may be good at removing a particular type of contaminant while being ineffective at removing another. "We need to think about the whole soup when we think about treatment," she says. What's more, Remucal explains, the mixture of contaminants may impact the body differently than any one chemical on its own. </p><p>Richardson's preferred treatment method is filtering the water with granulated activated carbon, followed by a low dose of chlorine.</p><p>Granulated activated carbon is essentially the same stuff that's in a household filter. (EWG recommends that consumers use a <a href="https://www.ewg.org/tapwater/reviewed-disinfection-byproducts.php#:~:text=EWG%20recommends%20using%20a%20home,as%20trihalomethanes%20and%20haloacetic%20acids." target="_blank" rel="noopener noreferrer">countertop carbon filter</a> to reduce levels of disinfection by-products.) While such a filter "would remove disinfection by-products after they're formed, in the plant they remove precursors before they form by-products," explains Richardson. She coauthored a <a href="https://pubs.acs.org/doi/10.1021/acs.est.9b00023" target="_blank" rel="noopener noreferrer">2019 paper</a> that concluded the treatment method is effective in reducing a wide range of regulated and unregulated disinfection by-products.</p><br>
Greater Cincinnati Water Works installed a granulated activated carbon system in 1992, and is still one of relatively few full-scale plants that uses the technology. Courtesy of Greater Cincinnati Water Works.<p>Despite the technology and its benefits being known for decades, relatively few full-scale plants use granulated active carbon. They often cite its high cost, Richardson says. "They say that, but the city of Cincinnati [Ohio] has not gone bankrupt using it," she says. "So, I'm not buying that argument anymore."</p><p>Greater Cincinnati Water Works installed a granulated activated carbon system in 1992. On a video call in December, Jeff Swertfeger, the superintendent of Greater Cincinnati Water Works, poured grains of what looks like black sand out of a glass tube and into his hand. It was actually crushed coal that has been baked in a furnace. Under a microscope, each grain looks like a sponge, said Swertfeger. When water passes over the carbon grains, he explained, open tunnels and pores provide extensive surface area to absorb contaminants.</p><p>While the granulated activated carbon initially was installed to address chemical spills and other industrial contamination concerns in the Ohio River, Cincinnati's main drinking water source, Swertfeger notes that the substance has turned out to "remove a lot of other stuff, too," including <a href="https://ensia.com/features/drinking-water-contamination-pfas-health/" target="_blank" rel="noopener noreferrer">PFAS</a> and disinfection by-product precursors.</p><p>"We use about one-third the amount of chlorine as we did before. It smells and tastes a lot better," he says. "The use of granulated activated carbon has resulted in lower disinfection by-products across the board."</p><p>Richardson is optimistic about being able to reduce risks from disinfection by-products in the future. "If we're smart, we can still kill those pathogens and lower our chemical disinfection by-product exposure at the same time," she says.</p><p><em>Reposted with permission from </em><em><a href="https://ensia.com/features/drinking-water-disinfection-byproducts-pathogens/" target="_blank">Ensia</a>. </em><a href="https://www.ecowatch.com/r/entryeditor/2649953730#/" target="_self"></a></p>
EcoWatch Daily Newsletter
- Most Meat Will Be Plant-Based or Lab-Grown in 20 Years, Analysts ... ›
- Lab-Grown Meat Debate Overlooks Cows' Range of Use Worldwide ... ›
- Will Plant-Based Meat Become the New Fast Food? - EcoWatch ›
One city in New Zealand knows what its priorities are.
Dunedin, the second largest city on New Zealand's South Island, has closed a popular road to protect a mother sea lion and her pup, The Guardian reported.
piyaset / iStock / Getty Images Plus
- No Country Is Protecting Children's Health, Major Study Finds ... ›
- 'Every Child Born Today Will Be Profoundly Affected by Climate ... ›
By Jeff Masters, Ph.D.
Earth had its second-warmest year on record in 2020, just 0.02 degrees Celsius (0.04°F) behind the record set in 2016, and 0.98 degrees Celsius (1.76°F) above the 20th-century average, NOAA reported January 14.
Figure 1. Departure of temperature from average for 2020, the second-warmest year the globe has seen since record-keeping began in 1880, according to NOAA. Record-high annual temperatures over land and ocean surfaces were measured across parts of Europe, Asia, southern North America, South America, and across parts of the Atlantic, Indian, and Pacific oceans. No land or ocean areas were record cold for the year. NOAA National Centers for Environmental Information
Figure 2. Total ocean heat content (OHC) in the top 2000 meters from 1958-2020. Cheng et al., Upper Ocean Temperatures Hit Record High in 2020, Advances in Atmospheric Sciences
Figure 3. Departure of sea surface temperature from average in the benchmark Niño 3.4 region of the eastern tropical Pacific (5°N-5°S, 170°W-120°W). Sea surface temperature were approximately one degree Celsius below average over the past month, characteristic of moderate La Niña conditions. Tropical Tidbits
- NASA and NOAA: Last Decade Was the Hottest on Record - EcoWatch ›
- Earth Just Had Its Hottest September Ever Recorded, NOAA Says ... ›