The answer simply is yes, we do need salt. But we get plenty of salt in the processed foods we eat, from meats and from plants. So even if we are not supplementing salt we still get salts in our diet.
What if I don't eat processed food ; would it be enought ?
Yes, the body regulates its salt balance. If low the body conserves salts. If high the body eliminates them.
I mean :
If I undertand well; the sodium in foods is actually sodium chloride, right ?
In processed foods the sodium is primarily sodium chloride or sodium bicarboante. In natural sources it can occur as sodium chloride or other salts such as carbonate.
Also potassium containg foods is usually chloride potassium ?
Potassium chloride, yes, or other potassium salts such as potassium sodium tartrate.
I concerned about how to get chlorine from food source for the HCl production by the stomach.
I don't really understand how to get it .
When I look at the chart food source considering somebody who would take only unprocessed food I mainly see eggs, wheat and rye and beef ( which I don't eat) to get chlorine.
Now what if somebody don't eat those foods ?
Plants pick up salts from the soil so you are going to get salts, including chlorides. You will also get these from meats. So it really is not hard to get the salts you need from diet.