Video: Eliza McCartney urges young athletes against supplement use

As the pressure on young athletes to perform at an early age continues to grow, more aspiring sportspeople are turning to supplements to help - without knowing exactly what they're taking.

Olympic bronze medallist Eliza McCartney has linked up with Drug Free Sport New Zealand to join a new campaign aimed at warning young people about the risks of taking supplements.

The 20-year-old believes it's not worth the risk taking supplements because you never know what exactly what you're taking.

"They don't give you a shortcut, then there's a chance when you get into professional sport, the supplements you take can be contaminated. There's no guarantee - you don't know what you're taking," she told Newshub.

"I can totally understand why you'd see this product and think, 'That's going to give me more muscle, I'm going to get stronger, I'm going to do better', but that's why we need to get these messages out there that food is all you need."

That's why Drug Free Sport New Zealand is promoting McCartney's "food first" attitude to other young athletes to tackle a growing problem.

"We need more education around supplements and food," she said.

"You can get everything from food. Supplements are a shortcut - there just doesn't seem to be enough education about that."