Did anyone tell you to reduce salt intake because it would lead to elevation in blood pressure? It is not exactly the salt, but they are unknowingly referring to the sodium present in the salt.
Sodium is a micronutrient, mineral that is important in the body to maintain the homeostasis and also regulate the balance of fluids and electrolytes. It also helps in regulating the blood pressure. It also plays a role in the stimulation of the muscle and nerve cells, along with the transport of nutrients.
Sodium at physiological level
Sodium ions are found in higher concentrations in the extracellular fluid of cells than in intracellular fluid and the skeleton. Sodium is absorbed mostly in the distal small bowel and the colon. As we know, every cell in the body maintains homeostasis by balancing the fluid concentrations, sodium along with other mineral potassium is maintained between extracellular and intracellular by sodium-potassium pump activity. The sodium-potassium pump actively (using energy from ATP) transports sodium and potassium ions to and fro the cell.
Sodium also regulates the electrolyte balance and blood pressure. And this is how sodium and hypertension (high blood pressure) are connected. High levels of sodium increase the pressure in the blood flow, leading to hypertension.
Sodium in health
Deficiency in sodium usually doesn't occur, but most populations world-wide are found to consume more sodium than the recommended intake. This excess sodium doesn't come from normal consumption of daily food, but from the consumption of a variety of processed and packaged foods. With this excess consumption, high sodium levels not only leads to hypertension but kidney disease, gastric cancer and bone related disorders (osteoporosis due to loss of urinary calcium).
Deficiency or low sodium levels occurs only in conditions such as sodium-losing kidney diseases, diarrhea, vomiting, extreme sweating, excessive intake of diuretics and so on. That is when electrolytes intake will be recommended.
High levels of sodium also can pave the way to organ damage independent of hypertension such as vascular dysfunction, arterial stiffening, changed renal function, left ventricular hypertrophy, deposition of sodium ions in the skin, cerebral circulatory dysfunction, alterations in the sympathetic nervous system, and changed in the bone calcium content (Robinson et al., 2019).
Recommendations
According to Institute of Medicine and American Heart association, the adequate intake of sodium from daily intake of foods is 1500 mg (3-4 grams of salt) for 9-50 years population of both genders. An upper limit (UL) of 2300 mg (5 grams of salt or 1 teaspoon) per day is recommended for all those above 14 years of age. Whereas these recommendations apply to healthy individuals, the recommendations vary depending on the existing aforementioned diseases.
According to WHO, a daily recommendation of ≤ 2000 mg sodium is set, which also can avoid the iodine deficiency leading to thyroid diseases by the use of iodized salt.
Diet types such as DASH Diet is also recommended to help lower or prevent hypertension where it limits the intake of high sodium foods along with unhealthy fats and sugary foods.
Food sources
Most of the foods that we consume contain sodium, such as bread, milk, cheese, eggs, chicken, vegetables, and fruits. All these are from the food groups and should be consumed in balanced proportions.
We add sodium in many forms in foods preparations,
- to enhance the taste
- to increase the shelf life,
- prevent the growth of bacteria and other microorganisms.
Intake of whole food sources in appropriate proportions and reducing the processed and packaged foods would help in decreasing the overall sodium levels in the body to adequate recommended levels.
References
- Grillo, A. et al. (2019) ‘Sodium Intake and Hypertension’, Nutrients, 11(9). doi: 10.3390/NU11091970.
- Haddy, F. J. (2006) ‘Role of dietary salt in hypertension’, Life Sciences, 79(17), pp. 1585–1592. doi: 10.1016/j.lfs.2006.05.017.
- Robinson, A. T., Edwards, D. G. and Farquhar, W. B. (2019) ‘The Influence of Dietary Salt Beyond Blood Pressure’, Current Hypertension Reports. Current Medicine Group LLC 1. doi: 10.1007/s11906-019-0948-5.
- Strazzullo, P. and Leclercq, C. (2014) ‘Sodium’, Advances in Nutrition, 5(2), p. 188. doi: 10.3945/AN.113.005215.
