Yes, it is perfectly fine for him to take. Creatine is a natural substance that is found in many foods such as steak. There are many benefits from creatine, and they're noticable.. Hence it's popularity.
There are a few things though. Since creatine does lend itself to water retention, he should increase his fluid intake. If he doesn't, he may suffer from muscle cramps---not good if he's playing baseball. Another way to subside the muscle cramps is to increase his potassium intake. (eat a banana a day!). Make sure he drinks it with grape juice or some type of non-acidic juice high in simple sugars.
Justin
