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Niacin (Vitamin B3) NUTR 624 – Vitamin Metabolism 6/25/2014 Chantal Otelsberg Niacin (B3) In terms of dietary intake, the combination of nicotinic acid and nucleotide-bound nicotinamide=niacin status Tryptophan is the third form of B3 that that is a precursor to for NAD (essential amino acid) Nicotinomide is the form of Niacin in supplements Where do I find Niacin? Historical Anecdotes Based on niacin deficiency, corn contains niacin Corn is a tightly bound structure, which is heat stable and is sensitive to alkaline treatment Native Americans developed various alkaline processing techniques to release existing niacin Importance of process not recognized when Columbus brought corn to Europe Pellagra outbreak occurred in outdoor labor workers, where sun-induced lesions occurred among those niacin deficient Similar outbreaks in Spain, Italy, and Egypt during 1700s and 1800s Nicotonic Acid first isolated in 1867, active role of vitamin was not identified until 1937 1906-NAD+ identified in yeast extracts Redox capabilities understood in 1936 1915-Dr. Joseph Goldberger: Conducted clinical trials on pellagra induced prison populations Pellagra cured/prevented through balanced diet and yeast supplements 1949-NADH formation with ATP production understood 1966-first publication on ATP-ribose formation, which aided in understanding pellagra Digestion of Niacin NAD and NADP needed to enable absorption, both present in food B6(pyrophosphatase) required for phosphate hydrolysis of NADP Due to negative electron charge of phosphate • Nicotinomide and nicotinic acid absorbed in stomach • More readily absorbed in the small intestine (sodium dependent facilitated diffusion) • High concentration of Niacin, passive diffusion Absorption • Nicotinamide and nicotinic acid formed slowly in stomach lining • Absorption in small intestine more rapid • Mechanisms of absorption not clear in current research • Nucleotides degraded in upper small intestine to form free nicotinamide • Low concentrations absorbed by sodium- dependent faciliated diffusion/proton cotransportors/anion antiporters • Higher concentrations absorbed by passive diffusion Absorption Absorbed through brush border in small intestine Nicotinamide converted to NADportal circulation Liver takes up remaining nicotinic acid from portal blood Nicotinic Acid and Tryptophan converted to NAD once in the liver Transport In plasma-niacin found in nicotinic amide bloodand nicotinic acid 1/3 of nicotinic acid (plasma) bound to plasma proteins bloodnicotinamide and acidcell membrane by simple diffusion Nicotinic acid transport kidney tubules and red blood cells require carrier Metabolic Function Coenzyme Transfer H electrons from one part of cell to another Provide energy to fuel metabolic reactions Aiding electron transport chain Non-redox Roles NAD acts as donor to form ADP-ribose and of modification of proteins associated with chromosomes Needed for DNA repair, replication, and transcription Niacin Deficiency Originally thought to be caused by disruptions in redox cycling (only metabolic role of niacin at the time) Due to ADP-ribosylation functions of NAD Deficiency mainly caused by NAD+ pool depletion Malabsorption Increased sensitivity to DNA damage Cancer Bone Marrow Esophagitis and Esophogeal ulcerations Deficiency Four D’s of deficiency: 1. Dermatitis • • 2. Dementia/Delerium • • • 3. Headache/apathy Loss of memory confusion Diarrhea • 4. Pellagra – “rough skin” Similar to sunburn Gastrointestinal manifestations Death • If left untreated Treatment 500 mg of nicotinamide daily –several weeks Possible riboflavin supplementation to oral lesions Possible thiamin supplementation for treatment of peripheral nerve problems DRI/RDI/AI Infants 0 - 6 months: 2* milligrams per day (mg/day) 7 - 12 months: 4* mg/day *Adequate Intake (AI) Children 1 - 3 years: 6 mg/day 4 - 8 years: 8 mg/day 9 - 13 years: 12 mg/day Adolescents and Adults Males age 14 and older: 16 mg/day Females age 14 and older: 14 mg/day Tolerable Upper Limit Children – 10-20 mg/d Adults – 35 mg/d *vasodilatory effects Assessment Urinary metabolites through urinalysis Serum and red blood cell indicators due to NAD concentrations related to NAD:NADP concentration in erythrocytes Interactions Niacin synthesized in body from tryptophan Scientists are currently debating how important the tryptophan to niacin pathway is in human nutrition Process requires vitamin B6 to occur Therefore, tryptophan and vitamin B6 could increase deficiency of niacin Primary Research Majewski, M., & Lebiedzinska, A. (2014). The evaluation of selected shellfish as a source of niacin in nutrition and therapy of modern human. Polish Annals of Medicine, 69. • Niacin analysis that was conducted showed differences between the various types of seafood • • • • Microbial method Vitamin extracted using enzymatic hydrolysis – papain and diastase Used 100g of seafood for DRI for men and women Among the analyzed seafood, the best source of niacin came from the 100 g of oyster meat (containing 1.16 mg niacin) • Determined that increased consumption of seafood might contribute to reduce the risk of civilization diseases morbidity, Critical Thinking Diagram/Describe the several general areas of metabolism in which NAD(NADH) and NADP(H)-dependent enzymes are involved. References Majewski, M., & Lebiedzinska, A. (2014). The evaluation of selected shellfish as a source of niacin in nutrition and therapy of modern human. Polish Annals of Medicine, 69. Gropper, S. A., Smith, J. L., & Groff, J. L. (2009). Advanced nutrition and human metabolism. Australia: Wadsworth/Cengage Learning. Shils, M. E., & Shike, M. (2006). Modern nutrition in health and disease. Philadelphia: Lippincott Williams & Wilkins. Deficiency Diseases (History of Medicine). (n.d.). Retrieved from http://www.blatner.com/adam/consctransf/historyofmedicine/5-deficiencydiseases/5deficdis.html Guide to Vitamn B3-Niacin (Nicotinic Acid). (n.d.). Retrieved from https://www.meschinohealth.com/books/vitamne_b3_niacin#vit2 Niacin: MedlinePlus Medical Encyclopedia. (n.d.). Retrieved from http://www.nlm.nih.gov/medlineplus/ency/article/002409.htm Template Provided By www.animationfactory.com 500,000 Downloadable PowerPoint Templates, Animated Clip Art, Backgrounds and Videos