Excessive intakes of sodium chloride (NaCl) lead to an increase in the volume of fluid in blood vessels (plasma) and fluid between cells as water is pulled from cells to maintain normal sodium concentrations. However, as long as water needs can be met, normally functioning kidneys can excrete the excess sodium and restore the system to normal (60). Ingestion of large amounts of salt may lead to nausea, vomiting, diarrhea, and abdominal cramps (61).
Abnormally high plasma sodium concentrations ('hypernatremia') generally develop from excess water loss, frequently accompanied by an impaired thirst mechanism or lack of access to water. Symptoms of hypernatremia in the presence of excess fluid loss may include dizziness or fainting, low blood pressure, and diminished urine production.
Severe hypernatremia may result in swelling ('edema'), hypertension, rapid heart rate, difficulty breathing, convulsions, coma, and death.
Hypernatremia is rarely caused by excessive sodium intake (e.g., the ingestion of large amounts of seawater or intravenous infusion of concentrated saline solution).
Tolerable upper intake levels
The European Food Safety Authority has decided that the available data are not sufficient to establish an upper level for sodium from dietary sources (62).
The U.S. Food and Nutrition Board has established an upper level intake (UL) for sodium based on the adverse effects of high sodium and sodium chloride (salt) intakes on blood pressure, a major risk factor for cardiovascular and kidney diseases (5):
Age Group | UL for sodium (g/day) | UL for salt (g/day) |
| Infants 0–12 months | not determined* | not determined* |
| Children 1–3 years | 1.5 | 4.8 |
| Children 4–8 years | 1.9 | 4.8 |
| Children 9–13 years | 2.2 | 5.5 |
| Adolescents 14–18 years | 2.3 | 5.8 |
| Adults 19 years and older | 2.3 | 5.8 |
* Not determined. Intake should be from food or formula only.
The UL for sodium may be lower for those who are most sensitive to the blood pressure effects of sodium, including older people, African Americans, and individuals with hypertension, diabetes, or chronic kidney disease.
Drug interactions
Please note:
Because of the potential for interactions, dietary supplements should not be taken with medication without first talking to an experienced healthcare provider.