**1) Sodium is an essential nutrient** so you need to consume it regularly. The safe minimum sodium intake for individuals who do not sweat excessively is said to be 200 mg sodium (500 mg salt) per day.

[Recommended Dietary Allowances: 10th Edition, 1989][1], minimum intake for *salt:*

> In consideration of the wide variation of patterns of physical
> activity and climatic exposure, a safe minimum intake might be set at
> **500 mg/day.** Such an intake is substantially exceeded by usual diets in
> the United States, even in the absence of added sodium chloride.

**2) When sweating a lot, you may need more than 5 grams of sodium per day:**

[Sweat rate and sodium loss during work in the heat (PubMed, 2008)][3]:

> People working in moderately hot conditions for 10 hours on average
> will lose between 4.8 and 6 g of sodium (Na) equivalent to 12–15 g of
> salt (NaCl) depending on acclimatisation.

**3) What can help to prevent kidney stones?**

According to [Nutritional Management of Kidney Stones (Nephrolithiasis) (
Clinical Nutrition Research)][4], these dietary measures can help reduce the risk of calcium kidney stones:

 - low in sodium (2-3 g sodium/day)
 - high in potassium (in fruits and vegetables)
 - high in calcium (at least 1,000 mg/day)
 - low in animal protein
 - only moderate intake of vitamin C (<1,000 mg/day; avoiding vitamin C supplements and fruit juices as a source of fluid)

**4) Treatment**

Diet does not likely cure the established kidney stones. A doctor can tell what is the optimal treatment for a given type and size of stones.


  [1]: https://www.ncbi.nlm.nih.gov/books/NBK234935/
  [2]: https://www.heart.org/-/media/data-import/downloadables/8/2/0/pe-abh-why-should-i-limit-sodium-ucm_300625.pdf
  [3]: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2267797/
  [4]: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4525130/