I keep running into the myths about salt.
The three most common are:
Kosher salt is better for you.
Rock salt is not for eating.
Reducing salt reduces high blood pressure.
Let me take them in reverse order.
Too much salt is bad for you, too little salt is bad for you and too much Sodium salt compared to the amount of Potassium salt is bad for you. The best is a comfortable balance of Potassium and Sodium salts, which normally means eating more green vegetables and less processed foods, especially commercial pizza and deli meats.
The amount of salt to use is much more tricky to establish because of the variables of weight, activity level, living temperature, fluid intake, fluid retention, kidney function and hidden salts in your diet.
A shepherd in sub-Saharan Africa might need a bit more than a couch potato in the USA.
Rock salt is often edible and a lot of table salt is ground rock salt. The most popular at the moment is Himalayan pink salt, which is not from the Himalayas at all but from Khewra Salt Mine, located in Khewra, Jhelum District, province of Punjab. It is over-priced, has a number of scams associated with it and some of its minerals may be in unpleasant amounts. The pink colour is from the iron in the halite.
Kosher salt is a scam to charge you more for less and line the pockets of dietary regime that has managed to get its methods equated with being healthier. The larger crystals mean you tend to use less salt for the same apparent volume, so there is the reduction in Sodium. However, much of it contains yellow Prussiate of soda as an anti-caking agent, so check your ingredient list, it should just say salt. When the ingredients start to be in alchemist's language pay attention, as it is really Sodium ferrocyanide and your stomach acid breaks the bond between the iron and the cyanide.
My recommendation is that you eat more greens, consume much less prepared food (see my Notes for all the names of MSG) and get a good quality rock or sea salt that does not have claims of magical powers around it, just use it judiciously.
The fresher your foods, the less salt you need for flavour, and eventually you find yourself reaching for the salt only when you need it.
If you want pink rock salt (halite) just buy the stuff from South Am