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.

First Health effects of salt
Too much or too little salt in the diet can lead to various cramps in the muscle, dizziness, or electrolyte disturbance. This can cause neurological problems, or death. Drinking too much water, with insufficient salt intake, puts a person at risk of water intoxication (i.e hyponatremia).

Second Health effects of salt
The effect of high salt consumption on long term health outcomes is controversial. Some associations include:
  • 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.

Source: Article on Health effects of salt, submitted to Wikipedia