World number one Serena Williams said she is supplement-free in the wake of Maria Sharapova's failed drugs test.

Sharapova sent shockwaves through tennis on Monday after revealing she had tested positive for recently banned substance meldonium at the Australian Open in January.

The five-time grand-slam champion insisted she was not aware the drug had been added to the World Anti-Doping Agency's (WADA) list of banned substances as of the start of the year.

Williams was quizzed about Sharapova on the eve of her first match at the BNP Paribas Open on Thursday, and the 21-time major winner said she does not take supplements.

"I'm terrified [of them], to be honest. It would just be a really bad situation if that was me," Williams said.

"Plus, my sister [Venus] went through a lot of illnesses and with her going through that, she was able to introduce me into a really vegan and raw, kind of really vegetable, whole raw world that I really enjoyed. And I was able to see a lot of benefits in my game and my body in general from that.

"Just even from a health perspective, I've never been a big fan of taking anything."

Despite the news, Williams said: "The majority of the players play with integrity. They do things when they're out there because they want to be the best they can the right way.

"It's just like the world. We live in a massive world with billions of people, and there are a few people who do things and it makes people scared, but that doesn't make the whole world a bad situation and a bad place.

"That's the same thing with tennis. The majority of players here, for years and years and years, really pride themselves on having integrity and playing with that. I think that beyond these two situations, we're still out there and we're still working hard."