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 (NaCl) 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 (fluid balance) 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 (WHO) recommended that adults consume no more than 5 grams (0.18 oz) (just under a teaspoon) of salt per day, an amount providing about 2 grams (0.071 oz) 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 (5 g or more of salt per day) and insufficient potassium intake (less than 3.5 grams (0.12 oz) per day) 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 (equivalent to about 7.5 g of salt) may increase the risk for cardiovascular disease and early death. The cardiovascular benefits of reducing salt consumption are similar to population-wide reductions in obesity, cholesterol, and tobacco use.
Acute effects Hypernatremia (high blood sodium level, above 145 mEq/L) 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 (about 1 g per kg of body weight). 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 (ET-1) decrease of 14% associated with a 45% increase in flow-mediated dilation (FMD). 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 (BH4) 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 (cardiac enlargement): "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 (fluid retention): A decrease in salt intake has been suggested to treat edema. Kidney disease: Excessive salt (sodium) 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 (CVD) events. Low sodium intake level was a mean of <115 mmol (2645 mg), usual sodium intake was 115–215 mmol (2645–4945 mg), and a high sodium intake was >215 mmol (4945 mg), 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 Microplastic 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.
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