Actually, table salt, sea salt and kosher salt all have almost the exact same amount of salt in them. The extra mineral content you get from sea salt is pretty minimal. The only real difference is taste and texture. Table salt usually contains iodine and this is used to help prevent certain thyroid diseases. Sea salt is made from evaporating water from different ocean areas so depending where it comes from, the taste will vary. Some people find that the larger grain of kosher and sea salt makes them use less, but what I find is people mistake these salts as being healthier choices and just use more: defeating the whole purpose.
Whatever you choose to use, just be aware that overall we want to reduce our sodium intake to avoid high blood pressure and water retention (about 1tsp per day total from foods and what we add). Try using other spices like garlic, pepper and basil in your cooking instead salt where possible.