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Vitamin B-6 Caitlyn Beck Vitamin B-6 Overview B-6 is a family of 3 compounds: pyridoxal, pyridoxine, and pyridoxamine. All 3 can become active B-6 coenzymes Pyridoxal Phosphate (PLP) B-6 or Pyridoxine Vitamin B-6 in Foods Stored in muscle tissues of animals More readily absorbed Whole-grains Leading sources in US: fortified ready-toeat cereals, poultry, beef, potatoes and bananas. Can be lost when foods exposed to heat and other processing Vitamin B-6 Needs RDA 1.3 mg/day for men and woman up to age 50 For older adults, RDA increases 1.7 mg/day for men, 1.5 mg/day for momen Daily Value= 2 mg Average daily intake is 2.5 mg in adult men, and 1.7 mg for women Vitamin B-6 Upper Level Upper Level for adults 100 mg/day Vitamin B-6 supplements Irreversible nerve damage Bodybuilders, women attempting to treat for PMS Painful skin patches, extreme sensitivity to sunlight, nausea, and heartburn Absorption, Transport, Storage and Excretion of B-6 Absorption is by passive diffusion Coenzyme form converted to free vitamin form for absorption Portal vein Muscle Liver phosphorylated Blood Albumin tissue main storage site Excess B-6 generally excreted in urine Functions of B-6: Metabolism Amino acid metabolism Coenzyme for transamination reactions that transfer amino groups– allows synthesis of nonessential amino acids Without PLP, every amino acid would be essential PLP helps convert homocysteine to amino acid cysteine PLP required for release of glucose from glycogen Helps to maintain blood glucose concentration Functions of B-6: Synthesis of Compounds PLP catalyzes a step in the synthesis of heme PLP required for synthesis of several neurotransmitters Serotonin, dopamine, norepinephrine, gamma-aminobutyric acid, histamine PLP in Vitamin formation Other Vitamin B-6 Functions Normal immune function Regulation of gene expression Effects on health: Cancer Cognitive function Carpal tunnel syndrome Premenstrual syndrome Nausea and vomiting in pregnancy Vitamin B-6 Deficiency Rare in North America Symptoms: Seborrheic dermatitis, microcytic hypochromic anemia, convulsions, depression, confusion Elderly, blacks, smokers, users of oral contraceptive agents, alcoholics, underweight or consume poor diets Medications Pharmacological Use Supplemental vitamin B-6 has a long history as a treatment for: Carpal tunnel syndrome Premenstrual syndrome (PMS) Nausea during pregnancy EAL Study on Vitamin B-6 Does supplemental folate and/or Vitamins B6 and B12 reduce homocysteine levels and subsequently reduce coronary events? Homocysteine relationship with the development of brain disorders, bone disorders and cardiovascular disease Schnyder et al (2002) Homocysteinelowering therapy (272 patients) Result: Lower serum homocysteine levels in supplemental group vs. control group 553 patients with successful angioplasty Placebo (281 patients) Rimm et al (1998) 658 incident cases of nonfatal MI 281 cases of fatal CHD 98,462 female RNs; 30-55 yrs old Risk of CHD lowered with high intake of folate & B-6 Controlling for CVD risk factors Risk of CHD reduced w/ folate & B-6 MV Result: Intake of folate and vitamin B-6 above the current recommended dietary allowance may be important in the primary prevention of CHD among women. Toole et al (2004) Low dose group (200 µg pyridoxine) 2,954 people with nondisabling ischemic stroke High dose group (25 mg pyridoxine) Result: Both decreased total serum homocysteine, however, the high vitamin dose group had a larger decrease at one month, one year, and 2 years. In Conclusion… Supplemental folate and/or Vitamins B6 and B12 reduced homocysteine levels but there was no significant evidence that it also subsequently reduced coronary heart events. QUESTION TIME! • MAJOR ROLE! • Coenzyme for transamination reactions that transfer amino groups to allow the synthesis of nonessential amino acids. • Convert homocysteine to the amino acid cysteine. • Release of glucose from glycogen– maintain How is the pyridoxal blood glucose concentration phosphate (PLP) coenzyme used in amino acid metabolism? • • • • Fortified ready-to-eat cereals Poultry, beef, fish Potatoes Bananas What are some good food sources of Vitamin B-6? • • • • • Seborrheic dermatitis Microcytic hypochromic anemia Convulsions Depression Confusion What are some signs of Vitamin B-6 deficiency? Resources Wardlaw, G. M. (2013). Wardlaw's Perspectives in Nutrition, 9th edition. New York: McGraw-Hill. Academy of Nutrition and Dietetics. Does supplemental folate and/or Vitamins B6 and B12 reduce homocysteine levels and subsequently reduce coronary events? Retrieved September 2013, from Evidence Analysis Library: http://andevidencelibrary.com/evidence.cfm?evidence_summar y_id=98&auth=1 Schnyder. Effect of homocysteine-lowering therapy with folic acid, vitamin B12, and vitamin B6 on clinical outcome after percutaneous coronary intervention: the Swiss Heart study: a randomized control trial. JAMA 2002; 288: 973-9. Rimm EB, et al. Folate andvitamin B-6 from diet and supplements in relation to risk of coronary heart disease among women. JAMA. 1998 Feb 4; 279 (5): 359-364 Toole. Lowering homocysteine in patients with stroke to prevent recurrent stroke, myocardial infarction, and death: The Vitamin Intervention for Stroke Prevention (VISP) Randomized Controlled Trial. JAMA 2004; 291: 565-75. http://ods.od.nih.gov/factsheets/VitaminB6-QuickFacts/
