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WATER-SOLUBLE VITAMINS CHAPTER 13 LEARNING OUTCOMES • Identify the water-soluble vitamins • List important food sources for each water-soluble vitamin • Describe how each water-soluble vitamin is absorbed, transported, stored and excreted • List the major functions of and deficiency symptoms for each water-soluble vitamin 2 LEARNING OUTCOMES • Describe the toxicity symptoms from the excess consumption of certain water-soluble vitamins • Distinguish between vitamins and non-vitamins, such as carnitine and taurine 3 OVERVIEW OF WATER-SOLUBLE VITAMINS • Storage in body tissues is minimal • Risk of toxicity less than fat-soluble • Many of the B vitamins act as coenzymes, which are important for energy metabolism 4 5 PRESERVING NUTRITION IN WATER SOLUBLE VITAMINS T or F: Most fruits and vegetables will last longer if you refrigerate them. T or F: You should trim, cut, and peel fruits and vegetables shortly after buying them to keep them from spoiling. T or F: The best way to cook vegetables is to boil them. T or F: Organic fruits and vegetables have more nutrition than non-organic. 6 THIAMIN (B1) • Foods • Pork, sunflower seeds and legumes • Bread and cereals (enriched grains) • Needs and upper level • RDA 1.2 mg/day men, 1.1 mg/day women • Fairly uncommon deficiency in US • No UL • Absorption in small intestine • Transported by RBC as TPP • Storage and excretion- little stored, excess excreted 7 THIAMIN (B1) 8 THIAMIN (B1) Functions • Thiamin helps the body's cells convert carbohydrates into energy. It is also essential for the functioning of the heart, muscles, and nervous system. • Co-enzyme-thiamin pyrophosphate (TPP) • Decarboxylation reactions: energy metabolism, amino acid metabolism 9 THIAMIN (B1) • Functions • Coenzyme for transketolase • Converts glucose to pentose (used to make DNA and RNA) 10 THIAMIN (B1) • Deficiency • Beriberi • Peripheral neuropathy (dry) • Congestive heart failure (wet) • Who? • • • • • 14 days with no thiamin White rice staple food Parental nutrition Severe vomiting and diarrhea Weight loss surgery • Wernicke-Korsakoff (Alcohol use) 11 RIBOFLAVIN (B2) • Foods • Milk, enriched grains, eggs and meat • Needs and upper level • RDA 1.3 mg/day men and 1.1 mg/day women • Uncommon deficiency in US • No UL • Absorption (needs HCl, absorbed in SI) • Transport by protein carriers • Storage and excretion-mostly excreted in urine 12 RIBOFLAVIN (B2) 13 RIBOFLAVIN (B2) • Functions • Co-enzymes: flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) • Energy metabolism • Citric Acid Cycle • Beta oxidation • Shuttles H atoms to the electron transport system • Other B vitamin functions (niacin, B6, and folate) • Antioxidant function 14 RIBOFLAVIN (B2) • Deficiency – Ariboflavinosis after 2 months – Most often seen in alcoholics, elderly, and adolescent girls – Light sensitive (milk containers are now plastic and cardboard to preserve riboflavin) – Use of some types of medications can increase riboflavin breakdown (drug used for sleeping and seizures) 15 15 NIACIN (B3) • Foods • Available as niacin or synthesized from tryptophan • Preformed niacin: Poultry, meat, fish, and enriched grains, some in coffee and tea • RDA expressed as niacin equivalents • 60 mg tryptophan =1 mg niacin • 1 gr of protein = 10 mg tryptophan 16 NIACIN (B3) 17 NIACIN (B3) • 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 • Absorption- passive diffusion • Transport-to liver • Stored in liver or excreted 18 NIACIN (B3) • Functions + • Co-enzymes NAD and NADPH • Required for catabolism of carbohydrate, fat and protein • Required in at least 200 reactions • Pharmacological use • Nicotinic Acid-lower LDL, increase HDL • 1-2 g (60x the RDA) 19 NIACIN (B3) • Deficiency • • • • Pellagra Corn based diets Casal’s necklace Once a significant problem in the US 20 NIACIN (B3) IS USED IN ALMOST EVERY METABOLIC PATHWAY 21 PANTOTHENIC ACID (B5) • Foods • Meat, milk and many vegetables • Needs and upper level • AI 5 mg • Deficiency uncommon in US • No UL • Functions • Co-enzyme A needed to form acetyl CoA and acyl carrier protein to build fatty acids Deficiencies are RARE 22 BIOTIN (B7) • Food sources • Whole grains, eggs, nuts and legumes • Needs and upper level • AI 30 micrograms • Deficiency uncommon in US • No UL • Absorption in small intestine • Storage in muscle, liver and brain or excreted in urine or bile 23 BIOTIN (B7) • Functions • Co-enzyme that adds CO2 to compounds • Required for metabolism of carbohydrates, fats and proteins • Deficiency • Biotinase enzyme deficiency • Skin rash, hair loss, convulsions, impaired growth) • Excessive consumption (>12) of raw eggs (avidin) 24 VITAMIN B-6 (PYRIDOXAL, PYRIDOXINE, PYRIDOXAMINE) • Foods • Meat, fish, poultry, fortified cereals, potatoes • Needs and upper level • RDA 1.3 mg/day women 1.7 mg/day men • Deficiency uncommon in US • UL 100 mg day • Permanent nerve damage • Absorption via passive diffusion • Transport to liver, phosphorylated • Storage in liver or excreted 25 WHOLE GRAINS BETTER THAN ENRICHED 26 VITAMIN B-6 (PYRIDOXAL, PYRIDOXINE, PYRIDOXAMINE) 27 VITAMIN B-6 (PYRIDOXAL, PYRIDOXINE, PYRIDOXAMINE) • Functions • Metabolism • PLP coenzyme involved in more than 100 enzymatic reactions, all involving nitrogen (ie needed for amino acid metabolism) • Synthesis of compounds • Heme, neurotransmitters, vitamins (niacin) • Deficiency • Very poor diet, alcoholism, medications (Parkinson’s) • Anemia, convulsions, confusion, depression 28 TRANSAMINATION USES B6 29 VITAMIN B-6 (PYRIDOXAL, PYRIDOXINE, PYRIDOXAMINE) • Pharmacological use • Carpal tunnel syndrome • PMS (no significant benefit) • Nausea during pregnancy 30 FOLATE (B9) • Folic Acid • Synthetic sources of folate • Foods • Liver, legumes and leafy green vegetables • Now fortified grains • Needs and upper level • RDA 400 micrograms/daily • Dietary Folate Equivalents (DFE) • UL 1 mg • May mask B-12 deficiency • Concern is with synthetic sources 31 FOLATE (B9) 32 FOLATE (B9) • Absorption via passive diffusion • Transported to liver, travels in blood or bile • Excreted in urine or feces • Functions • Central co-enzyme form: tetrahydrofolic acid (THFA) • DNA synthesis 33 FOLATE DEFICIENCY • Megaloblastic anemia • Neural Tube defects • Maternal deficiency of folate plus genetic predisposition • All women capable of getting pregnant urged to take in 400 micrograms of folic acid • Current fortification yields about 200 micrograms of folic acid daily 34 MEGALOBLASTIC ANEMIA 35 VITAMIN B-12 VITAMIN B-12 (COBALAMIN) • Foods • Animal products • Needs and upper level • RDA 2.4 micrograms daily • Average intake 2-3 times RDA • No UL 36 VITAMIN B-12 (COBALAMIN) • Absorption, transport, storage and excretion • Stomach: • B12 freed from foods by HCl • Free vitamin binds to Rprotein • SI • Pancreatic lipases frees B12 from R-protein • Free vitamin binds with intrinsic factor to enhance absorption • B12-intrinsic factor complex travels to liver where it can be stored 37 VITAMIN B-12 (COBALAMIN) 38 VITAMIN B-12 (COBALAMIN) • Functions • Required for enzymatic reactions • Formation of THFA, needed for nucleic acid synthesis • Formation of methionine from homocysteine, needed to metabolize homocysteine and make methyl groups Methylated Folate B12 THFA Methylated-B12 Methionine (methyl groups) Homocysteine 39 VITAMIN B-12 (COBALAMIN) • Deficiency • Pernicious Anemia • Macrocytic/Megaloblastic Anemia • Neurological changes • Homocysteine • At risk for deficiencies: Atropic gastritis (elderly) and malabsorption, vegetarians • Treatment • Monthly injection • Nasal gel • Oral doses (1-2 mg) • Passive diffusion 40 WHO WOULD BE AT MOST RISK FOR VITAMIN B12 DEFICIENCY? • • • • Someone on the Atkins diet Someone who never eats fruits and vegetables Someone who takes large doses of antacids Someone who drinks alcohol heavily 41 CHOLINE (AN ESSENTIAL NUTRIENT ALTHOUGH NOT A B VITAMIN • Foods-in the form of lecithin (naturally occurring and added) • Milk, liver, eggs and peanuts • Needs and upper level • • • • AI 550 mg/daily men 425 mg/daily women Can be synthesized by the body Deficiency is rare UL 3.5 grams (fishy smell, low blood pressure, vomiting, GI upset) 42 CHOLINE 43 CHOLINE Absorption in small intestine, then to liver Transport in blood Storage in all tissues Excreted in urine or converted to betaine or methyl groups • Functions • • • • • Phospholipids, lipoproteins, cell membranes and a precursor to acetylcholine (neurotransmitter) 44 VITAMIN C • Foods • Citrus fruits, peppers and green vegetables • Needs and upper level • RDA 90 mg/day men 75 mg/day women • Smokers need an additional 35 mg/day • UL 2 grams/day (GI upset) • Absorption efficiency changes with consumption • Storage in glands, WBC, eyes, and brain and excreted in urine 45 VITAMIN C 46 VITAMIN C • Functions • Collagen synthesis • Synthesis of other vital compounds (amino acids, hormones, carnitine, neurotransmitters) • Antioxidant activity (eyes, cancer) • Iron absorption • Immune function (WBC) 47 VITAMIN C • Deficiency • Scurvy • Cancer, heart disease • Colds 48 COLLAGEN SYNTHESIS REQUIRES VITAMIN C 49 VITAMINS AND CANCER • Cancer is caused by changes (mutations) to the DNA within cells. The DNA inside a cell contains a set of instructions telling the cell how to grow and divide. Errors in the instructions may allow a cell to become cancerous. • What do gene mutations do? A gene mutation can instruct a healthy cell to: • Allow rapid growth of mutated genes • Fail to stop uncontrolled cell growth • Make mistakes when repairing DNA errors 50 VITAMINS AND CANCER • Role of vitamins • Prevent DNA damage • Control gene expression • Play a role in DNA synthesis • What foods? • Will more of these foods (i.e. supplements) protect you further? 51 ROLE OF VITAMINS 52 VITAMIN-LIKE COMPOUNDS • Needed for normal metabolism • Synthesized by the body and found in foods • Increased need during rapid growth and some disease states • Often found in infant formulas 53 CARNITINE • Carnitine • Made from lysine and methionine and found in meat and dairy • Transports fatty acids from cytosol to mitochondria for energy metabolism • Used as weight loss aid or exercise aid 54 TAURINE • Taurine • Made from methionine and cysteine and found in foods of animal origin • Functions as antioxidant, helps with insulin action, and needed for cell differentiation and growth • Used in kids with cystic fibrosis and preterm infants 55 TABLE 13_03A 57 NUTRITION AND PUBLIC HEALTH •Two most common serious birth defects of the spine and brain are spina bifida and anencephaly •Incomplete closure/formation of the neural tube •300,000 infants yearly worldwide 58 IN 1992, THE U.S. PUBLIC HEALTH SERVICE FOLIC ACID RECOMMENDATION • All women capable of becoming • pregnant should consume 400 micrograms folic acid daily • 400 mg is the quantity in most multivitamin supplements that has been associated with a reduced risk in the large observational studies 59 USE AND KNOWLEDGE OF FOLIC ACID IN WOMEN OF CHILDBEARING AGE IN 1995 • Heard of folic acid 52% • Knew folic acid can prevent birth defects 9% • Knew folic acid should be taken before pregnancy 2% • Took folic acid daily 28% March of Dimes Birth Defects Foundation, Gallup Polls 1995 60 FOLIC ACID FORTIFICATION • The FDA issued a regulation to go into effect by January 1998 mandating that all enriched cereal grain products (flour, rice, bread, pasta, corn grits, corn meal, farina, macaroni and noodle products) be added with 140 g folic acid/100 g of the cereal grain product. • This program was designed to increase average folate intake by ~100 µg/d, although reports have indicated it may be closer to 200 µg/d. EFFECT OF FORTIFICATION IN THE US ON PREVALENCE OF NTDS Study Results Honein et al. 2001 19% decrease in NTD rates Williams et al. 2004 26% decrease in NTD rates 62 WHY MIGHT INCREASED SYNTHETIC FOLIC ACID INTAKE BE ASSOCIATED WITH ADVERSE EFFECTS? •Folic acid is the synthetic version of the vitamin. •The safe upper limit (UL) for adults is 1 mg of folic acid. – Masking a B12 deficiency. •High folate intakes can increase the progression of cancer in those who already have cancer. 63