For the human body, salt is both an essential metal and toxic at a high dose. The most common form of sodium comes from sodium chloride, a salt. However, too much salt and arteries become stiff, and the risk of heart disease and cardiovascular disease increases. The majority of dietary salt comes from processed foods.
Probably the most famous book is The Salt Fix. A rambling book claiming low salt is responsible for everything from lower sex drive to insulin resistance. The book is logical and simplistic, with abundant citations taken out of context. In summary, the book is almost completely incorrect.
One of the classic studies about salt and hypertension is the DASH sodium study. In these studies, the study participants were fed the diet with varying amounts of salt. These studies are expensive and often not done, but powerful. Additionally, the lower levels of salt, the lower the blood pressure. In fact, a low-sodium DASH diet led to a reduction of blood pressure equivalent to one blood pressure pill.
In contrast, "The Salt Fix" states that decreasing levels of salt led to increasing blood pressure and heart disease. The Salt Fix explanation is that lower salt leads to increased levels of renin, angiotensin, and aldosterone (hormones that would increase blood pressure). His conclusion is the opposite of hundreds of articles and much analysis. Such as here, here, and here.
Another false claim, "The Salt Fix," stated the DASH study showed an increase in LDL, cholesterol, and triglycerides.
The DASH diet showed no significant impact at all.
Salt is salt. It is NaCl. Some have minor amounts of contaminants and other metals in them, which give them color. It is not enough to make a significant impact on your body chemistry or your health.
This salt comes from about 200 miles away from the Himalayas, it is mined in Pakistan. Sounds better to say it is from the Himalayas, but it isn't. Thus, salt is mined much like the salt from Utah. The reason for the pink color is various contaminants. While many tout benefits of this salt, the additional minerals found in Pink salt are insignificant. Thus, the salt is expensive, pink, and mainly decorative.
Celtic salt is from the coast of France, where the salt water is evaporated to get the salt. In contrast, pink and white salt are mined from the old oceans. Celtic salt has more trace minerals than pink salt or white salt. However, the amount of minerals in these salts is not of consequence to humans.
Marathon runners and endurance athletes have died from low salt levels in the blood (hyponatremia). Drinking too much water, or non-salty beverages is one reason for this.
Sweating is not a major loss of salt in athletes. The average athlete will sweat about 15-65 mEq/Liter, with a maximum of 2 liters per twenty-four hours.
The major problem with those with low blood sodium after endurance athletic events is drinking too much water. Adding salt to the fluids does not improve performance, nor does it.
Some fear the anti-caking agents used in table salt. Sodium and Potassium ferrocyanide sound horrible because of the cyanide. However, ferrocyanide does not break down into toxic cyanide. Still, those who have not taken Chemistry 101 don't understand this. After all, salt itself has "chloride," which kills when it is chlorine gas.