 If you volunteer for this study, you will come to the General Clinical Research Center GCRC at Shands Hospital for a screening visit. There approximately 27.5 mL of blood 5 12 teaspoons will be taken from a vein in your arm. This will be used for tests to determine whether you are receiving adequate amounts of vitamin B6 and other vitamins, to analyze a part of the genetic information in certain blood cells that relates to how your body processes some nutrients, and to confirm your general health. If the vitamin B6 content of your blood is higher than the range needed for this study, which sometimes occurs from eating fortified foods, you might be asked to give another blood sample 2 teaspoons after several weeks to have the screening test repeated. You will also be asked questions about your health and a detailed assessment of your regular diet will be carried out. Your general health will be confirmed by taking a medical history, physical exam, and standard blood tests including liver, kidney, bone marrow function, cholesterol and urine analysis. To take part in this study, you must be in good health and in adequate nutritional status for vitamin B6 and other vitamins. 