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Sodium and your healthThe good old friend of ours, sodium (Na), is macro-mineral in everyday's use at most everyone's table. Its primary source is sodium chloride, a coarse whitish powder we all know as "salt".
What is it that we need sodium for? You may be surprised how important for your health is this soft metallic element. As a major body electrolyte, it is essential for creating and maintaining the spark that keeps us alive: bioelectricity.
Being crucial for the cellular function and survival, sodium is directly related to the organ function as well. For instance, with its cellular buddy phosphorus, is directly related to the function of your kidneys.
More specifically, high sodium levels (that is, high sodium to phosphorus - and other nutrients - ratio), can be pro-inflammatory and result in infection of the right kidney. If it is high phosphorus, it is the left kidney that is affected18. The cure is most often as simple as balancing sodium, or phosphorus, with the rest of minerals.
And of course, there is that dreaded sodium link to high blood pressure. Statistically, your chances to be affected are 1 in 3. Not too bad, and even if you are "salt sensitive", that does not necessarily mean it will make you hypertensive. You still need salt to stay alive and well: too little can be just as bad as too much, and everyone has to find near-optimum individual level.
However, there are other metabolic pathways where sodium can affect your health. In some people, low sodium level can result in low blood pressure, dehydration and, longer-term, kidney stones, arthritis, and fatigue.
Elevating sodium intake resolves these problems, unless the aldosterone (steroid hormone) levels are also low. This hormone is needed for sodium retention, and when it is low, higher sodium intake results in the opposite effect: it is readily excreted together with lots of fluid, which worsens the above low-sodium symptoms. In such case, low aldosterone levels need to be corrected (by supplementing vitamin B1, choline or iron), which would likely also resolve low-sodium status18.
Sodium is needed to control the body fluid level, as well as the osmotic pressure between the cells. Make sure you have enough of it, but not too much. Other than elevated blood pressure and water retention (edema), excessive sodium intake can cause nausea, gout, kidney damage and, in extreme cases, stroke and coma. Since the kidneys can't excrete sodium without calcium, excessive sodium intake has lowering effect on your calcium levels.
Sodium DRI (Dietary Reference Intakes, the most recent set of dietary recommendations set by the government) for an average healthy adult is set at 1.5g (slightly lower after 50 years of age), with the safe limit set at 2.3g a day. Since the table salt sodium content is around 40% by weight, this translates into the safe limit of 6g of salt a day.
Most world populations have higher, or significantly higher sodium intake. In the U.S. it averages about 3.5g a day (nearly 9g of salt), and in some East Asia regions it can be more than twice as much. Average worldwide range of daily consumption is between 100 and 200 mmol, which translates to 2.3-4.6g of sodium (5.75-11.5g of salt).
This suggests that the safe limit may be somewhat higher than the officially recommended. Since the average body sodium content is nearly 0.14% by weight, or 1.4 g per kg of body weight, it is unlikely that variations in intake of few grams of salt (i.e. 1-2g of sodium) would pose significant problem for body's very capable regulatory mechanism. As always, this general assessment is subject to possibly wide variations in individual sensitivities.
Natural sodium food sources are invariably low in their salt content, with the exception of some sea algae. Thus most of your sodium intake comes from salt.