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Vitamin B12. Emily Skeen. B12 Background. Discovered in 1948 due too its relationship to pernicious anemia Discovered by Dr. Lester Smith a chemist in England Only vitamin containing metal (cobalt): compounds with B12 are collectively referred to as “ cobalamins ” Water-soluble
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Vitamin B12 Emily Skeen
B12 Background • Discovered in 1948 due too its relationship to pernicious anemia • Discovered by Dr. Lester Smith a chemist in England • Only vitamin containing metal (cobalt): compounds with B12 are collectively referred to as “cobalamins” • Water-soluble • Required for RBC formation, DNA synthesis, and neurological function
Metabolic Pathway Bind to Intrinsic Factor Dietary B12 Release
Food Sources and Intake Levels • RDA: age 14+ years= 2.4 mcg/day • No tolerable upper intake level has been set by the Food and Nutrition Board • Sources: • Animal products • Generally not present in plant foods • Fortified breakfast cereals, and other fortified foods
Benefits • Help decrease homocysteine levels -> reducing risk for cardiovascular disease • Studies relating low B12 to Alzheimer’s and cognitive decline • Role in energy metabolism and ‘energy enhancer’
Deficiency • Characterized by megaloblastic anemia, fatigue, weakness, constipation, loss of appetite, and weight loss • Neurological issues and decreased cognitive function • During infancy: failure to thrive, movement disorcers, develpmental delays, and megaloblastic anemia • Deficiency typically treated with injections
Relationship to Folic Acid • Large amounts of Folic Acid can mask effects of B12 deficiency • Corrects the megaloblastic anemia • Does not correct the neurological damage • Permanent nerve damage can occur if B12 deficiency not treated • Folic acid should not exceed more than 1000 mcg/day
Exercise Study #1 • Compared Vitamin B12 and folate status of recreational endurance athletes and inactive controls by modern biomarkers • 72 athletes (38± 7y), 46 inactive controls (38± 9y) • Training not standardized • Serum levels of B12, folate, methylmalonic acid, holotranscobalamin II, and homocysteine (Hcy) measured • Hcy slightly lower in athletes, similar serum B12 levels but slightly lower in athletes
Exercise study #2 • 12 trained subjects (52.33± 2.4years) and 12 untrained subjects (56.23± 0.9 years) • Total homocysteine and total cysteine levels were measured at rest in both groups • Also during incremental exercise performed on cycle ergometer until exhaustion
Conclusion • Vitamin B12 is an important cofactor in the methionine pathway • Aids in converting homocysteine to methionine • Its main relationship to exercise stems from its ability to aid in this process • B12 deficiencies -> increase in homocysteine, decrease in RBC production, protein synthesis, and other substrate formation
References • Gaume V, M. F., Figard H, Simon-Rigaud ML, N'Guyen UN, Kentelip JP, Berthelot A. (2005). Physical Training Decreases Total Plasma Homocysteine and Cysteine in Middle-Aged Subjects. Annals of Nutrition & Metabolism, 49(2), 125-131. • Hermann M, O. R., Scharhag J, Kindermann W, Herrmann W. (2005). Altered Vitamin B12 Status in Recreational Endurance Athletes. International Journal of Sports Nutrition and Exercise Metabolism,15(4), 433-441. • Higdon, J. (2003). Vitamin B12. Vitamin B12, from http://lpi.oregonstate.edu/ infocenter/vitamins/vitaminB12/ • Vitamin B12. (2011). Office of Dietary Supplements: National Institutes of Health. Retrieved from http://ods.od.nih.gov/factsheets/VitaminB12 HealthProfessional/