Health effects of salt

The health effects of salt are the conditions associated with the consumption of either too much or too little salt. Salt is a mineral composed primarily of sodium chloride and is used in food for both preservation and flavor. Sodium ions are needed in small quantities by most living things, as are chlorine ions. Salt is involved in regulating the water content of the body. Both sodium and chlorine ions are used for electrical signaling in the nervous system, among other biological roles.
Salt is usually high in ultra-processed and hyperpalatable foods. In 2020, the World Health Organization recommended that adults consume no more than of salt per day, an amount providing about of sodium per day. The WHO further recommends that salt intake be adjusted for those aged 2 to 15 years old based on their energy requirements relative to those of adults. High sodium consumption and insufficient potassium intake have been linked to high blood pressure and increased risk of heart disease, stroke, and kidney disease.
As an essential nutrient, sodium is involved in numerous cellular and organ functions. Several national health organizations recommend limiting sodium consumption to 2.3 g per day. However, some studies have found that sodium intake that is below 3 g per day may increase the risk for cardiovascular disease and early death. The cardiovascular benefits of reducing salt consumption are similar to reductions in obesity, cholesterol, and tobacco use.

Acute effects

causes thirst, and due to brain cell shrinkage may cause confusion, muscle twitching, or spasms. With severe elevation, seizures and comas may occur. Death can be caused by ingestion of large amounts of salt at a time. Deaths have also been caused by the use of salt solutions as emetics, typically after suspected poisoning.
Hyponatremia, or blood sodium levels below 135 mEq/L, causes brain cells to swell; the symptoms can be subtle and may include altered personality, lethargy, and confusion. In severe cases, when blood sodium falls below 115 mEq/L, stupor, muscle twitching or spasms, seizures, coma, and death can result.

Long-term effects

Major health organizations and recent reviews state that high consumption of salt increases the risk of several diseases in children and adults.
Excess sodium consumption increases blood pressure. Approximately 15% of adults have inverse salt sensitivity, with blood pressure increasing from eating less salt. Some studies suggest a U-shaped association between salt intake and mortality, with increased mortality associated with both excessively low and excessively high salt intake. Larger reductions in salt intake lead to larger decreases in blood pressure.
Normotensive overweight/obese patients who were salt restricted for six weeks showed an endothelin 1 decrease of 14% associated with a 45% increase in flow-mediated dilation. ET-1 has autocrine action on endothelial cells causing the release of nitric oxide. Another study using middle-aged or older adults with moderately elevated blood pressure taking sodium chloride tablets or placebo tablets for a few weeks showed that sodium restriction increased nitric oxide and tetrahydrobiopterin resulting in improved FMD without affecting blood pressure. The suppression of endothelium production of nitric oxide is the result of oxidative stress on the vasculature.
Health effects associated with excessive sodium consumption include:

Stroke and cardiovascular disease.
High blood pressure: Evidence shows an association between salt intakes and blood pressure among different populations and age ranges in adults. Reduced salt intake also results in a small but statistically significant reduction in blood pressure.
Left ventricular hypertrophy : "Evidence suggests that high salt intake causes left ventricular hypertrophy. This is a strong risk factor for cardiovascular disease, independently of blood pressure effects." "...there is accumulating evidence that high salt intake predicts left ventricular hypertrophy."
Edema : A decrease in salt intake has been suggested to treat edema.
Kidney disease: Excessive salt intake, combined with an inadequate intake of water, can cause hypernatremia. It can exacerbate renal disease. A US expert committee reported in 2013 the common recommendation by several authorities "to reduce daily sodium intake to less than 2,300 milligrams and further reduce intake to 1,500 mg among persons who are 51 years of age and older and those of any age who are African-American or have hypertension, diabetes, or chronic kidney disease", but concluded that there was no health-outcome-based rationale for reducing intake below 2,300 mg, and did not have a recommendation for an upper limit.

A meta-analysis investigated the association between sodium intake and health outcomes, including all-cause mortality and cardiovascular disease events. Low sodium intake level was a mean of <115 mmol, usual sodium intake was 115–215 mmol, and a high sodium intake was >215 mmol, concluding: "Both low sodium intakes and high sodium intakes are associated with increased mortality, consistent with a U-shaped association between sodium intake and health outcomes".

Salt-preserved foods

Possible effects of microplastic contamination

contamination in sea salt has been confirmed in all areas of the world, ranging from zero to 1,674 particles per kilogram. The most common particles are polypropylene, followed by polyethylene and nylon. Microplastic particles per kg sea salt tend to be higher when sourced from Asian countries. Salt sourced from India ranged from 115 to 560 particles/kg. Sea salt sourced from China reported more than 400/kg. Microplastics also accrue in shellfish grown or harvested in regions with microplastic contamination of seawater, and are a significant contributor to human exposure. The extent to which humans are exposed to microplastics in foods and beverages can be assessed via measuring microplastics content in feces, but the health effects, if any, are poorly understood.

Dietary recommendations

Recommended intakes of salt are usually expressed in terms of sodium intake as an Adequate Intake and a Tolerable upper intake level. Salt contains 39.3 percent of sodium by weight.

Country	Description	Sodium intake mg per day	Salt intake mg per day	Authority	Remarks
United Kingdom	The Reference Nutrient Intake defined for a typical adult	RNI: 1600	RNI: 4000	Scientific Advisory Committee on Nutrition	However, average adult intake is two and a half times the RNI. SACN states, "The target salt intakes set for adults and children do not represent ideal or optimum consumption levels, but achievable population goals." The Food Safety Authority of Ireland endorses the UK targets.
Canada	An Adequate Intake and Upper Limit recommended for persons aged 4 years or more.	AI: 1200–1500 UL: 1900–2300	AI: 3000–3750 UL: 5500–5750	Health Canada	"Canadians are consuming too much sodium without understanding the risks to their health. Canadians should lower their sodium intakes, as part of maintaining a healthy lifestyle, to reduce the risk of high blood pressure, stroke and heart and kidney disease."
Australia and New Zealand	An Adequate Intake and an Upper Level of intake defined for adults	AI: 460–920 UL: 2300	AI: 1150–2300 UL: 5750	NHMRC	Not able to define a recommended dietary intake
United States	An Adequate Intake and Upper Limit defined for adults. A different UL defined for the special group comprising people over 51 years of age, African Americans and people with hypertension, diabetes, or chronic kidney disease.	UL: 2300 UL for special group: 1500	UL: 5750 UL for special group: 3750	Department of Agriculture and Department of Health and Human Services	The Food and Drug Administration itself does not make a recommendation, but refers readers to the dietary guidelines given by this authority.
Sweden	An Adequate Intake and Upper Level of intake defined for adults	AI: 2000 UL: 2400	AI: 5000 UL: 6000	Swedish Food Agency	An excessive intake of sodium increases the blood pressure, which in turn can lead to increased risk of cardiovascular diseases and kidney failure. It is estimated that one forth of the adults in Sweden have high blood pressure, and almost half of all over 65 years of age. The Swedish recommendations are based on the Nordic Nutritional Recommendations.
Nordic countries	An Adequate Intake and Chronic disease risk reduction	UL: 1500 CDRR: 2300	UL: 2500 CDRR: 5750	The Nordic Nutritional Recommendations	Adverse effects of high intake are high blood pressure and increased mortality.

As of 2009 the average sodium consumption in 33 countries was in the range of 2,700 to 4,900 mg/day. This ranged across many cultures, and together with animal studies, this suggests that sodium intake is tightly controlled by feedback loops in the body. This makes recommendations to reduce sodium consumption below 2,700 mg/day potentially futile. Upon review, an expert committee that was commissioned by the Institute of Medicine and the Centers for Disease Control and Prevention reported that there was no health outcome-based rationale for reducing daily sodium intake levels below 2,300 milligrams, as had been recommended by previous dietary guidelines; the report did not have a recommendation for an upper limit of daily sodium intake.
The United States Centers for Disease Control and Prevention states that excess sodium can increase blood pressure and the risk for heart disease and stroke in some individuals. Therefore, health authorities recommend limitations on dietary sodium. The United States Department of Health and Human Services recommends that individuals consume no more than 1500–2300 mg of sodium per day.
Although sea salt is sometimes promoted as being healthier than table salt, both forms have the same sodium content.