Should you be watching your salt intake more closely? The full truth:

saltMany health organizations claim that high intake of salt causes or contributes to a number of serious health issues, including heart disease and high blood pressure; we’ve been warned repeatedly to limit salt in the diet.

But evidence collected over decades does not support the theory that it’s dangerous to consume salt. (1)

Some studies actually indicate that eating a diet very low in salt can be harmful.

Let’s sort through the facts and get clear on the role salt plays in our bodies, how much is too much, and the effects of salt on health.

The Nature of Salt

Sodium chloride (NaCl) is commonly called salt; it consists of 60% chloride and 40% sodium. Salt and sodium are used interchangeably to refer to this compound, which is often used to improve the flavor of food.

We get most of the sodium in our diets from salt, although it occurs naturally in small amounts in most foods.

Salt has been used as a preservative for centuries; the high amount of sodium in salt inhibits the growth of bacteria that can cause spoilage.

Depending on the type of salt, other minerals can be present in small amounts, such as zinc, potassium, iron and calcium; table salt often has added iodine. (2, 3)

These essential minerals act as electrolytes in our bodies, working to ensure proper muscle function, balancing fluid levels, and participating in the process of transmitting messages through the nervous system.

Salt is obtained through mining it from the earth or the evaporation of seawater or other water rich in minerals; table salt is the most common type available, and others include sea salt and Himalayan pink salt.

Flavor and texture varies between types, and the health effects of different kinds of salt are actually quite similar.

Your Heart on Salt

Many health authorities recommend keeping sodium intake below 2,300 mg daily. Certain groups and experts continue to insist a considerably lower amount is better. (4, 5, 6)

Salt is 40% sodium by weight, and 2,300 mg amounts to about a teaspoon of salt (6 grams). Estimates gathered from survey information indicate as many as 9 out of 10 Americans consume more than the recommended amount. (7)

We’ve been told eating too much salt jacks up blood pressure and raises the risk of suffering a stroke or heart attack, but the actual benefits of restricting sodium are in question.

Cutting back on sodium intake can make a dramatic difference in blood pressure levels for people who have a condition called salt-sensitive hypertension, but the average blood pressure reduction in healthy subjects is minimal. (8)

A 2013 study reported significant salt restriction practiced by healthy individuals dropped pressure by only 2.42 mmHg systolic and 1.00 mmHg diastolic. Here’s an example of how a person’s blood pressure measurement might change: 130/75 mmHg could be reduced to 128/74 mmHg. (9)

This is obviously not the drastic reduction one would hope for by removing most salt from the diet.

Recent review studies analyzing data gathered from multiple clinical trials found no evidence that restricting sodium decreases the risk of heart attack, stroke, or death. (10, 11)

Negative Effects of Low Salt Intake

We hear about the dangers of too much salt, but potential problems associated with too little salt don’t make headlines.

Studies with patients who significantly reduced sodium intake yielded the following data:

  • A meta-analysis of studies indicated heart failure patients restricting sodium had 160% higher risk of dying than those who did not. (12)
  • Eating less than 3,000 mg sodium daily was associated in several studies with a higher risk of dying from heart disease. (13, 14)
  • Restricting salt is linked with higher levels of LDL cholesterol (the bad kind), as well as elevated triglyceride levels. (15)
  • Type 2 diabetes patients who restrict sodium are at higher risk for death. (16)
  • Eating a low-salt diet has been associated in several studies with insulin resistance. (17, 18, 19)

Salt and the Digestive Process

Gastric cancer, which is also called stomach cancer, is the fifth most common type of cancer; it kills more than 700,000 people annually, ranking as the third leading cause of cancer deaths worldwide. (20)

Observational studies have linked high salt intake to an elevated risk of developing stomach cancer, and several hypotheses about why this may be so have been suggested, including:

  • Excessive salt may damage the lining of the stomach, which could lead to increased exposure to carcinogens. (21, 22)
  • High salt levels may encourage the growth of helicobacter pylori, the bacteria that can result in inflammation and gastric ulcers. (23, 24)

A review of studies published in 2012 analyzing data from more than 200,000 test participants showed that those who habitually consume high amounts of salt run a 68% higher risk of developing stomach cancer than people who eat a low-salt diet. (25)

The observational studies cited above cannot prove that high-salt diets raise the risk of stomach cancer, only that there is an association.

High-Salt Foods and Cutting Back

The majority of salt in a typical diet is from processed foods and restaurant foods. Estimates indicate that only about a quarter of most people’s salt intake comes from what is added to food when cooking at home or at the table. (26)

These foods are usually high in salt:

  • Instant and canned soup
  • Pickles
  • Snack foods like pretzels, potato chips, etc.
  • Soy sauce
  • Processed meats

Here are some others that might surprise you:

  • Cottage cheese
  • Certain breakfast cereals
  • Bread

Read food labels before making a purchase to determine how much sodium the product contains.

Some health conditions require a restriction of sodium, so if your doctor has advised you to watch your salt intake, it’s important to follow the guidelines you’ve been given. (27)

For healthy people who eat only minimal amounts of processed food and focus on whole, natural foods, there is probably no reason to be concerned about salt intake.

Summary: Restricting salt intake can have long term health benefits for people with certain conditions, but evidence does not support the practice of sodium restriction for many of the high-profile applications generally recommended, such as protecting heart health.

References:

  1. http://www.ncbi.nlm.nih.gov/pubmed/20888548
  2. http://onlinelibrary.wiley.com/doi/10.1111/j.1745-459X.2010.00317.x/abstract
  3. http://www.ncbi.nlm.nih.gov/pubmed/18620930
  4. http://www.who.int/nutrition/publications/guidelines/sodium_intake_printversion.pdf
  5. http://www.ncbi.nlm.nih.gov/pubmed/20089546
  6. http://www.cnpp.usda.gov/DietaryGuidelines
  7. http://www.ncbi.nlm.nih.gov/pubmed/22854410/
  8. http://www.ncbi.nlm.nih.gov/pubmed/8613190
  9. http://www.ncbi.nlm.nih.gov/pubmed/23558162
  10. http://www.ncbi.nlm.nih.gov/pubmed/25519688
  11. http://www.ncbi.nlm.nih.gov/pubmed/9519949
  12. http://www.ncbi.nlm.nih.gov/pubmed/21731062
  13. http://www.ncbi.nlm.nih.gov/pubmed/16490476
  14. http://www.ncbi.nlm.nih.gov/pubmed/21540421
  15. http://www.ncbi.nlm.nih.gov/pubmed/12535503
  16. http://www.ncbi.nlm.nih.gov/pubmed/21289228
  17. http://www.ncbi.nlm.nih.gov/pubmed/21036373
  18. http://www.ncbi.nlm.nih.gov/pubmed/10371376
  19. http://www.ncbi.nlm.nih.gov/pubmed/12691602/
  20. http://www.ncbi.nlm.nih.gov/pubmed/25220842
  21. http://www.ncbi.nlm.nih.gov/pubmed/21081930
  22. http://www.ncbi.nlm.nih.gov/pubmed/16450397
  23. http://www.ncbi.nlm.nih.gov/pubmed/17510398
  24. http://www.ncbi.nlm.nih.gov/pubmed/23989802
  25. http://www.ncbi.nlm.nih.gov/pubmed/22296873
  26. http://www.ncbi.nlm.nih.gov/pubmed/1910064
  27. http://www.ncbi.nlm.nih.gov/pubmed/22425103
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