Meanwhile, studies have shown that young athletes in northern European countries such as Britain, Finland and Germany often suffer from vitamin D deficiency. Proper levels can reduce the risk of stress fractures, inflammatory injuries and upper respiratory tract infections.
"You can get vitamin D in food sources (such as eggs, dairy and fish) but it's not as effective as sunshine production," Stevenson said.
"Those at risk are athletes training at 35 degrees or above latitude -- northern Europe, north China, North America -- as UVB rays are inadequate during the winter months from November to April.
"When we measured our elite tennis players we only found one athlete who was marginal with vitamin D, as he had been injured and was rehabbing indoors.
"There needs to be more research evidence looking at vitamin D and injury prevention -- most of the work is retrospective."
Most athletes use supplements to bolster their dietary intake, everything from everyday vitamins such as magnesium and iron plus products such as whey protein, creatine, carnitine and branched-chain amino acids (BCAAs) specifically aimed at improving performance and recovery.
But, with drug-testing standards improving year by year and the list of banned substances also increasing, there is a strong onus for athletes to be acutely aware of everything they put in their mouth.
"Most athletes are using quite a few supplements. They live an extreme life, the amount of training they do is extreme, they exercise way outside what the normal person would do, so it is important to supplement their diet," Corones says.
"There is a very fine line and it's something that athletes need to stay on top of. The onus is 100% on the athlete and we make that very clear to them from a young age that they are responsible for what goes in their mouth. No matter if it comes from their coach or their parents or their brother or their friend, they have to know what they're putting in their body.
"You might trust your coach 100% but if he gives you a bottle of tablets and tells you it's iron, it's still your responsibility to get that checked. We have hotlines where the athletes can call up and check anything, so it's pretty easy to find out if it's okay to take."
At this stage, with the Games underway and many athletes still waiting to begin their competitions, the emphasis is on refinement as opposed to strength building.
"It varies depending on where we are in the year," says Corones, who works for the New South Wales Institute of Sport in Sydney.
"Earlier on we want them to be carrying a bit of extra weight to reduce the chances of injury and illness, but then when it gets down to racing it's stripped down to the bare minimum," she says.
"We don't really get them to count calories, we more look at what areas of food groups they're eating from. You're looking at getting quality fats, making sure you get enough carbohydrates, and also the timing of the meal -- if you're swimming or doing gym.
"If you're doing gym there's a greater mechanical breakdown of the muscle so we need to eat more protein post the session, with a little bit pre the session."
A big part of Corones' job is making sure athletes learn the right food habits -- and this generally means breaking eating patterns formed at a young age.
"It's a pretty big education process for the athletes. There are still some that struggle with that concept that the less processed it is, the better it is for them," she says.
"Often early on in their careers, in their young teens, they do a lot of training and they want to grab the first thing that's quickest available because they're always hungry after training. So they get in the habit of having a bucket of hot chips after every training session. Obviously that's not great so we try to break those habits.
"We often find that the processed foods -- with the high salt and the high sugar content in them -- that the body can crave them. It's about trying to break those cycles and get them eating as well as they can."