Thanks for the good question, barbaryans <img src="/images/graemlins/smile.gif" alt="" /> . Athletes definitely have unique nutritional requirements. They ask more from their bodies which means they need more of certain nutrients.
I'm glad to hear you eat well. That's always a great beginning. Since it's so hard to get everything you need from the foods you eat, I suggest supplementing your diet with complete natural, whole food nutritional supplements.
Focus on essential fatty acids to help balance your hormonal system, a complete protein supplement to help build and repair your muscle tissue and antioxidants (vitamins A, C, E and Carotenoids and Flavonoids). Physical activity increases your need for antioxidants.
I would strongly suggest you stay away from carnitine and creatine. You'd be better off in the long run to focus on "complete" proteins as opposed to isolated amino acids. Your body desires a complete protein profile to work properly. Isolating specific aminos will cause imbalances in your body that can lead to other problems.
I hesitate at being more specific with quantities without more details. A public forum is not necessarily the place for such personal information. Work with these general recomendations and you'll know if you're getting the right amounts when you begin to notice more natural energy, faster recovery from a workout, better muscle tone development, less PMS (assuming you're female <img src="/images/graemlins/wink.gif" alt="" /> ) and fewer, if any, illnesses.
And, please keep in touch, barbaryans. We'd all like to hear about your progress and how you're doing. <img src="/images/graemlins/laugh.gif" alt="" />