As a whole - that said - I generally consider most supplements to be benign (not harmful) but with one disclaimer - buyer beware.
My suggestions are as follows:
- Follow and do not exceed recommended doses.
- Always check with your physician - some supplements may interact with medications that your are currently taking, or cause high blood pressure, kidney or liver problems. Remember to let your doctor know all medications or supplements that you are taking.
- Ask your physician to make sure that your kidneys and liver are working normally (confirmed by simple blood tests) before starting supplements.
- It is very likely that your physician can provide you information on supplements or other natural food products that might improve your sport function.