Everyone loves salt, right? Salt is one of our four main taste types and enhances the flavour of food. Salt is essential to the health of humans and other animals, but how much should we have and why?
Table salt is made up of two elements sodium and chlorine, and has been used in food manufacturing, seasoning, preserving and cooking processes for thousands of years. Usually salt is obtained from salt mines (in the mineral form of halite) or from the evaporation of seawater (sea salt). Table salt is a refined (cleaned) product which contains 97 - 99% sodium chloride. Anti-caking agents are added such as sodium aluminosilicate or magnesium carbonate, which help the salt flow freely, and sometimes people add a few grains of uncooked rice to the salt shaker to absorb extra moisture and prevent the salt from clumping.
Sodium and chlorine are essential minerals in the body; sodium is the main electrolyte which enables many biochemical and osmotic processes, so nerves and muscles work correctly. Sodium helps regulate our blood pressure and cardiovascular system, and therefore too much salt can cause hypertension or high blood pressure (1, 2).
Many people consume too much salt, mostly from adding salt to cooking, and consuming convenience processed foods. In the United States, 75% of the sodium eaten comes from processed and restaurant foods, 11% from cooking and table use and the rest from what is found naturally in foodstuffs (3). Excessive salt consumption can increase the risk of cardiovascular disease, stroke, kidney disease and increase your blood pressure (4, 5). The World Health Organisation recommends only 2000 mg of sodium daily, which is about what you get from 1 tsp or 5 grams of added salt (6). If you exercise a lot or are working outdoors and are a salty sweater you may need to add more salt to your food to replace your losses. Many athletes consume carbohydrate electrolyte drinks to enhance athlete performance, which help to replace sodium losses through sweat, and typically contain around 10 - 20 mmol/L sodium (7).
Iodine is a trace element and is often added to salt, due to our historical deficiency of this element in our diets leading to the development of goitre, which is an enlargement of the thyroid gland in adults or cretinisim in children (8, 9). A deficiency of iodine can cause lowered production of thyroxine leading to hypothyroidism and enlargement of the thyroid gland. Iodized salt has been used to correct these conditions since 1924, (10) and table salt is mixed with minute amounts of potassium iodide, sodium iodide, or sodium iodate. Iodine deficiency affects about two billion people around the world and is the leading preventable cause of mental retardation.
There are many varieties of salt: table salt (highly refined usually with iodine added), kosher salt (natural, coarser and flaky), unrefined sea salt, Himalayan pink salt (from salt mines), Celtic sea salt (grey colour), Fleur de Sea (tidal pond sea salt from Brittany, France), Kala Namak (Himalayan black salt where charcoal, bark, herbs are added), black Hawaiian salt (volcanic), Red Hawaiian, Smoked salt (smoked and flavours added). All edible salt is made up of sodium chloride, flavours may vary but the chemical composition is very similar.
In summary, a little salt daily is fine, if not essential for good health, however most of us need to monitor how much we use.