Ayurveda considers black salt to be a cooling spice that may be beneficial digestive and health benefits.
Black salt is also known to have many beneficial properties.
These include:
It may have benefits as a fat burner 
It may show anti-diabetic activity  
It may be an anti-hair fall agent 
It may be an effective antacid 
it may show haematinic (stimulate blood cell formation) activity
It may show anti-flatulent properties 
It may have anthelmintic (destroy parasitic worms) activity
It may have adaptogenic activity 
It may have demulcent (relieving inflammation) properties
It may be digestive stimulant 
It may have antioxidant benefits