It’s generally agreed by health experts that teens shouldn’t be using certain supplements, particularly some of those used to boost athletic abilities. Yet, according to CNN, more than two-thirds of vitamin stores still recommended a popular sports supplement — creatine — even when they were told the supplement was for a teen. It’s estimated that 30 percent of high school athletes are using this supplement, CNN said.

Creatine is one of 8 nutrients you can’t get from foods, and that’s why some people choose to take a supplement for it. Creatine is an amino acid found in animal foods that is important for muscle energy, proper function of your central nervous system, and brain health. But, it’s noteworthy that creatine can also be produced by the liver, so unless you’re a vegetarian who isn’t getting animal foods, you don’t really need a supplement for it.

Three important factors of fitness nutrition are a sufficient protein/high-fat/low-carb diet — which in and of itself will give you a source of creatine; getting enough essential amino acids, the most notable of which is leucine; and timing of meals. And while many athletes do this, carb-loading is not the most beneficial way to lose fat, gain muscle or boost your performance.

The bottom line is, in sports nutrition, the food you eat has an immense impact not only on your general health, but on the benefits you will ultimately reap from your workouts. This means making sure you have a proper balance of proteins, leucine and other essential amino acids that play a part in energy and sports nutrition ― and timing meals correctly. You also need to ditch energy drinks, sports drinks, most energy bars and even “healthy” drinks like vitamin water.