Chapter 13 Water Soluble Vitamins Overview of Water Soluble Vitamins Storage in is minimal Risk of toxicity less than fat soluble Easily destroyed during cooking Utilized in energy conversion Activated by digestion 50 90 of B vitamins are absorbed Marginal more common Enrichment Act Table B Vitamins Thiamin History Chemistry Functions First discovered in B complex B1 Very in alkali or basic solution Co enzyme TPP TPP involved in 2 energy production reactions Conversion of pyruvate to acetyl CoA Required for and branched chain amino acid reactions Thiamin Absorption and metabolism Thiamin Needs Sources RDA 1 2 mg day men 1 1 mg day women Average intake is 1 2 2 0 mg day thiamin riboflavin niacin iron folate Legumes Grains Feeding polished rice polished remove bran germ Neuritis inflamed nerves in legs Sunflower seeds Surplus is rapidly lost in urine non toxic Thiamin Deficiency Beriberi Mental depression Anorexia loss of appetite Constipation Neuro muscular pain Congestive heart failure Thiamin deficiency in alcoholics Disorientation Loss of short term memory Jerky eye movements Staggering gate Riboflavin Second B vitamin to be discovered B2 Chemistry and Properties Stable to basic solution heat Unstable in Riboflavin Absorption and metabolism Riboflavin Foods yogurt cheese from opaque containers enriched or whole grains eggs meat liver Needs and upper level RDA 1 3 mg day men and 1 1 mg day women Average intake is 1 5 2 1 mg day Non toxic Riboflavin Functions Co enzymes flavin mononucleotide FMN flavin adenine dinucleotide FAD Aids in breakdown of fat Antioxidant function Deficiency Cheilosis dry cracks at sides of mouth dry around nose Glossitis inflamed tongue magenta tongue purple Niacin Also called B3 Chemistry and Properties Humans can produce niacin 2 forms found in diet Body easily converts NA to nicotinamide Very stable and hard to breakdown Niacin Absorption and Metabolism Used for energy metabolism niacin precursor Can synthesize niacin 60 mg of tryptophan EAA 1 mg niacin 1 g of protein 10 mg tryptophan 100g protein 1g tryptophan Niacin Sources Eggs Meat Poultry Fish Whole and enriched Needs and upper level RDA 16 mg day men and 14 mg day women U S intake exceeds RDA UL 35 mg day applies only to supplements and fortification Niacin Functions NAD and NADPH needed for 20 metabolic pathways Required for catabolism of carbohydrate fat and protein Required for synthesis of fat Required in at least 200 reactions Niacin Deficiency rough skin Dry dark leathery skin on exposed parts of body Symptoms 4 D s Dementia Dermatitis Diarrhea and Death Pharmacological use lower LDL increase HDL Niacin Toxicity Impossible to get too much from diet Rx niacin available in form of nicotinic acid Rx day to lower serum cholesterol Can cause symptoms of Diabetes Liver disorders Vasodilation or can be produced if pantothenic acid is present Pantothenic Acid Present everywhere Chemistry and Properties Absorption Through GI tract Excess is excreted Function Requirements Integral in CoA metabolism AI 5 mg day average 15 mg day Sources Deficiency none Toxicity none Biotin Chemistry Critical role in TCA cycle Coenzyme for several pathways Properties Absorption protein in eggs binds to biotin Resulting compound is not absorbed in gut Only a problem with raw eggs not a problem after cooking Biotin Function Participates in Adding a carboxyl COOH to an existing C chain First step in Gluconeogenesis Lipogenesis NEAA synthesis Requirements AI adequate intake 30 g day DV 300mg No UL Biotin Sources Wide spread Organ meats Soy beans Fish Liver Whole grains Deficiency Symptoms Lethargy Hallucinations Facial rash Toxicity None reported Vitamin C Ascorbic acid Background All animals can synthesize vitamin C from glucose Except and guinea pigs Chemistry and Properties 6 C compound that has hydroxyl OH groups Most nutrient known Destroyed by Air Light Basic solution Exposure Vitamin C lost in food processing Vitamin C Ascorbic acid Absorption and Metabolism 100 of amounts absorbed Tablets large amounts only absorb 20 Excess out with feces Amount absorbed contributes to body pool of 1500mg 25 day reserve Vitamin C Functions Synthesis of other vital compounds Anti oxidant activity Iron absorption Immune function Vitamin C Ascorbic acid Requirements RDA Men 90 mg day Women 75 mg day Smokers 35 mg day UL 2000 mg day Sources Broccoli Bell peppers Oranges Grapefruit juice Vitamin C Ascorbic acid Deficiency Collagen molecules not maintained Not common Found in babies whose mothers had excessive vitamin C intake during pregnancy Movement is painful for infant Need increased vitamin C and the need to be weaned Toxicity Increased risk Kidney stones Cramping Pyridoxine B6 Chemistry 3 forms Pyridoxol plant foods Pyridoxal animal foods Pyridoxamine animal foods unstable sunlight inactivates Dry heat will also inactivate Pyridoxine B6 Absorption Vitamin B6 Functions Coenzyme for metabolic reactions Metabolism PLP coenzyme involved in amino acid metabolism Deamination Converts tryptophan to niacin Synthesis of compounds Neurotransmitters vitamins Vitamin B6 Foods Pyridoxine B6 Deficiency fish poultry fortified cereals potatoes Needs and upper level RDA 1 3 mg day women 1 7 mg day men UL 100 mg day Permanent Absorption is negatively impacted by Can result from altered tryptophan metabolism Inadequate B6 disrupts and their O2 binding ability Microcytic hypochromic anemia Pyridoxine B6 Can result from diet or Rx If 250x RDA or 325 mg Pharmacological use Neuromuscular dysfunction painful and irreversible PMS no significant benefit Nausea during pregnancy Cobalamin B12 Chemistry Central atom cobalt Absorption B12 is considered an Needs to bind to intrinsic factor parietal cell Parietal cells synthesize HCl in stomach About 50 of B12 is absorbed 1 3 of adults 60 yrs lose some parietal cell function B12 Absorption figure Cobalamin B12 Function 2 major functions Transforms folate into active form Folate is needed for DNA and RBC synthesis CNS integrity Maintenance of the myelin sheaths 3 5 year supply in liver Vitamin B12 Foods Needs and upper level RDA 2 4 micrograms daily Average intake 2 3 times RDA No UL Cobalamin B12 Deficiency Conditions Toxicity None Folic Acid or Folate Background Macrocytic Anemia Causes If eat animal products but lack intrinsic factor Intake Treatment Vegans need supplementation Named after best natural source Chemistry and Properties Folic Acid or Folate Function Cell division Amino acid metabolism