Salt, just like sugar, is an inexpensive way to make food taste good. One often observes people sprinkling salt over their food before tasting it, and some researchers suggest that the high consumption of salt is a habit, or even an addiction, learnt in childhood.
Many popular foods and snacks such as potato crisps, pretzels, nuts, and popcorn are flavoured with lots of salt. Throughout the ages salt has been used as a preservative and high quantities of salt are still found in some foods for this reason, such as processed meat products. The intake of salt is vital for certain chemical processes in the human body, but is too much salt, like too much sugar, necessarily bad for you?
What is salt?
Table salt is composed of two minerals, sodium, and chloride – both ionic compounds – which forms from the ionic bonding of sodium ions and chloride ions into sodium chloride. Ionic compounds mean they are particles that are electrically charged, either positive or negative. Sodium is positively charged and bonds with the negatively charged chloride.
Sodium separates from chloride when salt, being very soluble, dissolves in water and is easily absorbed into the bloodstream from the small intestine.
Sodium is the main positively charged ion (called a cation) of the fluid surrounding the cells in the body (called extracellular fluid), while a smaller amount is found in the skeleton and an even smaller amount in the fluid inside the cells (called intracellular fluid).
Chloride is the major negatively charged ion (called an anion) outside cells and in the blood. Chloride plays a role in maintaining the normal balance of fluids in the body.
Substances that become ions in solution, being either positively or negatively electrically charged, are called electrolytes. The most common electrolytes in the body are sodium, chloride, potassium, and bicarbonate. Potassium is the major positive ion inside cells in the body, while bicarbonate helps to maintain the normal levels of acidity in the blood and other fluids.
The role that sodium plays in the body
In a nutshell, sodium helps to keep the water balance in the body and plays a role in the normal nerve and muscle functions. (Water balance refers to the amount of fluid inside and around the cells in the body, as well as the amount of fluid in blood – referred to as blood volume.) The sodium ions are essential for the functioning of every cell in the body.
Sodium is obtained through food and drink and most of it is found in blood and in the fluid around cells. Sodium is lost through sweat and urine.
Interestingly, there is no direct mechanism for the body to analyze sodium content, but it is determined indirectly, mainly by vascular pressures. This means that the body interprets variations in vascular pressures as variations in sodium content. Certain blood vessel cells (called baroreceptors) that deform according to changes in pressure within blood vessels (intravascular pressure) is one of the factors that play a role in controlling sodium excretion in the kidneys.
These receptors trigger mechanisms to increase blood volume when sodium concentrations are too low, in two ways: – by stimulating the adrenal glands to release the hormone aldosterone, which triggers the kidneys to retain sodium; – and by the pituitary gland releasing the hormone vasopressin, which triggers the kidneys to conserve water.
The capacity of sodium, as one of the electrolytes in the body, to conduct electrical current, plays an important role in many processes in the body that require electrical signals for communication, such as in the brain, the nervous system, and muscles. Sodium helps maintain the right balance of fluids in the body; helps to transmit nerve impulses; and helps the contraction and relaxation of muscles.
Implications of too much or too little sodium in the body
Too high or too low levels of sodium can seriously impact one’s health.
Excess sodium: The kidneys can be overwhelmed with excess sodium, which results in the body retaining water to dilute the sodium. This in turn leads to increases in the levels of fluid surrounding cells and in the volume of blood in the bloodstream. Larger quantities of blood affect the heart (which must work much harder to pump the bigger volumes) and increase the pressure in blood vessels. Over the longer term the extra strain on the heart and blood vessels can stiffen the blood vessels, leading to high blood pressure and cardiovascular conditions such as heart failure, heart attack, and stroke. Over the longer-term hypertension may also lead to kidney disease, which is a chronic illness that can result in kidney failure.
Sodium deficiency: This condition is exceedingly rare, as salt is added to a variety of food and is found naturally in many foods. Deficiency can occur in impaired older people who do not eat or drink enough or have health conditions that deplete the body of sodium; or when sodium is depleted due to excess diarrhea, vomiting, or sweating.
“Sodium isn’t generally a nutrient that you need to look for, it finds you.”
So says Harvard about the abundance of sodium in commercially prepared foods. Unprocessed foods are low in sodium, such as fruit, vegetables, nuts, meats, fish, whole grains, and dairy products. The sodium intake from fresh foods is ample for the body’s needs.
An easy way to visualise the amount of sodium in food, is to compare it with a teaspoon of salt (scraped, not heaped), which contains close to 6 grams of salt, of which 2,4 grams (or 2400 mg )consists of sodium. While half the salt molecule is sodium, it is not half by weight, with sodium making up 40% and chloride 60% of the weight of salt.
Daily recommended intake: Various authoritative international guidelines, for the daily recommended sodium intake, recommend moderate amounts. For example, the World Health Organization sets the daily recommended intake as not more than 2000 mg of sodium, while the Nutritional Guidelines for Americans set an adequate daily intake as 1500 mg of sodium.
Low sodium food: Food with less than 120 mg sodium per 100 grams is regarded as a low sodium food.
High sodium food: food with more than 600 mg sodium per 100 grams is regarded as a high sodium food.
Other forms of sodium: Salt is not the only source of sodium. Other sources include baking soda (sodium bicarbonate), flavour enhancers such as MonoSodium Glutamate (MSG), preservatives such as sodium benzoate, sodium nitrite, and sodium sulphite, as well as antioxidants such as sodium ascorbate, often used in white wines.
Major dietary sources of salt: The average person may consume much more salt than the recommended guidelines, says the Mayo Clinic about the main sources of sodium in the diet:
- Processed and prepared foods are generally high in salt and in additives that contain sodium.
- Natural sources of sodium include all vegetables, diary products, shellfish, and meat. These foods may be low in sodium content, but it all adds up to the daily total.
- Salt is added in the kitchen and at the table. Salt is an ingredient in many recipes and sodium is found in many condiments. Some people habitually sprinkle salt on their food at the table.
Ways to cut back on salt: There are several ways to cut back on sodium in one’s diet.
- As a large percentage (estimated 75%) of added sodium comes from processed, take away, and commercially prepared foods, sodium intake can be vastly reduced by switching to fresh food such as fruit and vegetables. Fresh meat is lower in sodium than processed meat. Make sure to check the label for sodium content for any foods in a container, package, wrapper, or skin (such as processed meats).
- Cut down on highly salted foods, and snacks such as pretzels, potato- and corn crisps, anchovies, olives, and spreads. Some condiments are loaded with sodium, such as soy sauce, tomato sauce, other sauces, salad dressing, and mustard.
- Sprinkle less salt at the table. The golden rule is to taste the food first to find out if it really needs extra salt. Gradually sprinkle less salt over time, so your taste buds can adjust accordingly.
- Cut down on the amount of salt in recipes.
- Substitute salt with aromatic spices (but check for sodium content in mixed spices), herbs, and aromatic ingredients such as onions and garlic.
- Some labels may claim reduced or less sodium, which only means 25% less sodium than the regular version, which may be high in sodium. Rather opt for labels that indicate unsalted or no salt added.
As salt is an acquired taste, your taste buds will adjust in a few weeks as you reduce your intake of sodium. Ban the saltshaker from the table and only fetch it when really needed. Over time the preference for salty food diminishes and the true taste of the food itself can be enjoyed, with health benefits for the heart and many other organs.
Sodium in blood. Published online. Medical University of Michigan. USA. (www.uofmhealth.org)
Overview of sodium’s role in the body. Published online and reviewed April 2020. MSD Manual, Consumer Version. (www.msdmanuals.com)
Sodium. Published March 2014. Advances in Nutrition. Publication of the American Society for Nutrition. National Center for Biotechnology Information. National Library of Medicine. National Institutes of Health. USA. (www.ncbi.nlm.nih.gov)
The role of potassium and sodium in your diet. Published online. Centers for Disease Control and Prevention. USA. (www.cdc.gov)
Electrolytes. Published online and reviewed 24 December 2019. MedicineNet. (www.medicinenet.com)
Shaking out the facts about salt. Published February 2016. American Chemical Society. (www.acs.org)
Why is too much salt bad for you? Published 30 May 2013. Livescience. (www.livescience.com)
Salt and sodium. Published online. The Nutrition Source. Harvard School of Public Health. (www.hsph.harvard.edu)
How to convert sodium to salt (and salt to sodium). Published online and updated August 2020. Foodwatch. (www.foodwatch.com.au)
Sodium: How to tame your salt habit. Published 29 June 2019. Mayo Clinic. USA. (www.mayoclinic.org)