Govindam,

First I want to clear the myth about supplements( a thing added to something else in order to complete or enhance it), SUPPLEMENTS ARE NOT STEROIDS AT ALL. 

Simply, supplements are the PART of your diet HERE Part means, those nutrients which  we are not able to take from our daily roution diet.

But, One thing you should keep in mind that your supplements are  genuine so thats why you have to buy your stuff from any authorized store. and you can have your mass gainer if you want to increase more than 5 kgs of your body weight.