<qa>  What is the process that will test how effective vitamin B6 functions in helping your body use certainOnce you have completed all screening procedures you will be asked to eat meals prepared by the GCRC for 2 days, you will then participate in the procedure to test how effectively vitamin B6 functions in helping your body use certain amino acids. This will involve giving you a solution of certain amino acids by a vein in your arm over the course of 9 hours. 