Is there any disadvantage/ side effect to low sodium salt? when compared to salt, is low sodium salt definitely better alternative?

Probably no need: Views about sodium have changed over the years. The current consensus is higher sodium intake is harmless in the absence of high blood pressure and certain heart, kidney, liver or other metabolic problems. Probably you can use salt in cooking and salt your food to taste without worry. Salt substitues usually have potassium, which can have its own problems. If in doubt, check w/ your doctor.