Salt, sodium chloride, NaCl, is about 40% sodium and 60% chloride. It is ubiquitous and found in many different food items. It flavors food and is used as a binder and stabilizer. Salt has endured as an important part of our culture, and many different salt variants are available to meet our needs.
The use of salt is now universal. Salt is thought to have entered the human diet about 5,000 years ago. Ancient Chinese texts described more than 40 types of salt about 4,700 years ago (Peng-Tzao-Kan-Mu, pharmacology). It is a food preservative – as bacteria can’t thrive in the presence of a high amount of salt – that helped humans migrate longer distances.
The word “salary” was used to describe how Roman soldiers were paid for their duties with salt (Latin salarium). In 1930, Gandhi led thousands of Indians on a 240-kilometer salt march in defiance of the British Salt Act, which is considered a maiden event in India’s independence.
Today salt is used as a way to preserve foods to prolong foods’ shelf life.
The average American man and woman are estimated to consume 10.4 and 7.3 grams of salt per day respectively. The U.S. Department of Agriculture and Department of Health and Human Services recommend no more than 5.8 grams of salt (2.3 grams of sodium) per day, with a lower target of 3.7 grams for most adults (people over 40, blacks, patients with hypertension). One gram of sodium is equivalent to 2.5 grams of salt or sodium chloride.
It is estimated that we need about 500 milligrams of sodium daily for our vital functions. But too much sodium in the diet can lead to high blood pressure and stroke.
A study entitled “Salt Appetite” by University of North Carolina at Chapel Hill nephrologist Philip Klemmer, MD, showed that when he and a colleague went on an extremely low salt diet of 10 milliequivalents per day, they noticed a weight drop of 1.4 kilograms along with a drop in blood pressure.
Multiple articles have shown weight and blood pressure drop with lower salt intake. A paper by Kirsten Bibbins-Domingo, MD, PhD, and others published in the New England Journal of Medicine showed that reducing salt consumption by 3 grams per day reduced coronary heart disease in the U.S. by 60,000 to 120,000 cases per year; the number of strokes decreased 32,000 to 66,000 cases a year.
A study published in 1975 looked at the “salt-free culture” of South America’s Yanomami tribe, who had relied on food obtained by hunting and fruits. Of all the people studied in the tribe, the mean urine sodium excretion was 1.02 milliequivalents per day, whereas the mean systolic blood pressure was <110 mm Hg across all age groups. They also had high renin aldosterone levels given their high potassium, low sodium diet.
Salt consumption is a cultural thing, where consumption is driven by taste and our appetite for processed food.
Most salt we consume today comes as a preservative in foods that we buy. Table salt and salt added while cooking contribute to about 10% of salt consumption. (Figure below)
According to the Centers for Disease Control and Prevention (CDC), the top 10 salt contributors (in mg) are:
- Bread and rolls (80-230),
- Cold cuts/cured meats (1 bacon 194/1 beef jerky 443),
- Pizza, 1 slice (500-700),
- Fresh and processed poultry (300-700 mg),
- Soups (300-500),
- Sandwiches like cheeseburgers (700-1700),
- Cheese, 1-oz. slice (330-440),
- Pasta dishes like spaghetti with meat sauce (400),
- Meat dishes like meatloaf with tomato sauce (600-1100), and
- Snacks like chips, pretzels etc. (140).
This helps me talk salt to my patients, informing them that the real salt that one needs to cut is the salt that’s in packaged and processed foods. Feel free to sprinkle that salt on your watermelon!
Nishant Jalandhara, MD, is a clinical nephrologist practicing in the Greater Fort Worth area. His areas of interest are hypertension and chronic kidney diseases prevention and management with a special emphasis on home dialysis. He graduated from the Texas Medical Association Leadership College in May 2019.