• Health effects of salt

    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 (NaCl) and is used in food for both preservation and flavor. Sodium ions are needed in small quantities by most living things, as are chloride ions. Salt is involved in regulating the water content (fluid balance) of the body. The sodium ion itself is used for electrical signaling in the nervous system.

      Salt consumption has increased during modern times. Scientists have become aware of health risks associated with high salt intake, including high blood pressure in sensitive 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 (3750–5750 mg of salt) per day depending on age.

      As an essential nutrient, sodium is involved in numerous cellular and organ functions. Salt intake that is too low may also increase risk for cardiovascular disease and early death.

      Hypernatremia, a 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 use of salt solutions as emetics (typically after suspected poisoning), forced salt intake, and accidental use of salt instead of similar-looking sugar in food.

      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. Acute hyponatremia is usually caused by drinking too much water, with insufficient salt intake.

      Country Description Sodium intake
      mg per day
      Salt intake
      mg per day
      Authority Remarks
      United Kingdom The Reference Nutrient Intake (RNI) defined for a typical adult RNI: 1600 RNI: 4000 Scientific Advisory Committee on Nutrition (SACN) (2003) 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 (AI) and Upper Limit (UL) recommended for persons aged 9 years or more. AI: 1200–1500
      UL: 2200–2300
      AI: 3000–3750
      UL: 5500–5750
      Health Canada (2005)
      Australia and New Zealand An Adequate Intake (AI) and an Upper Level of intake (UL) defined for adults AI: 460–920
      UL: 2300
      AI: 1150–2300
      UL: 5750
      NHMRC (2006) Not able to define a recommended dietary intake (RDI)
      United States An Upper Limit (UL) defined for adults. A different upper limit defined for the special group comprising people over 51 years of age, African Americans and people with hypertension, diabetes, or chronic kidney disease (regardless of age). UL: 2300
      UL for special group: 1500
      UL: 5750
      UL for special group: 3750
      Department of Agriculture and Department of Health and Human Services (2010) The Food and Drug Administration itself does not make a recommendation, but refers readers to the dietary guidelines given by this authority.

      • Stroke and cardiovascular disease.
      • High blood pressure: Evidence shows an association between salt intakes and blood pressure among different populations and age range 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 can predicts left ventricular hypertrophy." Excessive salt (sodium) intake, combined with an inadequate intake of water, can cause hypernatremia. It can exacerbate renal disease.
      • Edema: A decrease in salt intake has been suggested to treat edema (fluid retention).
      • Stomach cancer is associated with high levels of sodium, "but the evidence does not generally relate to foods typically consumed in the UK." However, in Japan, salt consumption is higher.
      • Kidney 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.
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    • Health effects of salt