Supplementing with vitamins can increase cancer risk, so be cautious. Fat-soluble vitamins are especially risky because they are stored in the adipose tissue (fat cells) of your body. Water-soluble vitamins tend to be excreted in urine.

https://www.sciencebasedmedicine.org/vitamins-and-cancer-risk/
http://www.coloradocancerblogs.org/dietary-supplements-shown-to-increase-cancer-risk/