What amount of daily salt intake is ideal for a person? Does increased consumption cause any adverse effects on the health of the person?
The recommended daily intake of salt varies, but Nutrition Australia recommends 1.15-2.00 grams per day.
When you consume more salt than this, your blood pressure increases as a result of the body's compensatory mechanism for controlling the increase in plasma sodium. The body prefers to have higher blood pressure than to have a higher sodium concentration, as a high sodium concentration can be catastrophic and can lead to seizures and coma.
The mechanism behind the increase in blood pressure in order to control sodium concentration is as follows:
The increase in plasma osmolarity due to the increased plasma sodium causes the osmoreceptor cells located in the anterior hypothalamus near the supra-optic nuclei to shrink. This shrinkage of the osmoreceptor cells causes them to fire, sending nerve signals to nerve cells in the supra-optic nuclei, which eventually transmit signals to the posterior pituitary.
This results in increased release of the hormone ADH (anti-diuretic hormone) from the posterior pituitary. This ADH hormone then enters the blood stream, moves to the kidneys and increases the permeability of the collecting tubules to water, resulting in increased water resorption in the kidneys, leading to urine being more concentrated.
The net result is an increase in water resorption and an increase in blood volume and blood pressure.
High blood pressure is associated with many adverse health effects, particularly cardiovascular disease, including stroke and myocardial infarction.