Water-Soluble Vitamins Water soluble Readily excreted – expensive urine Can be lost from food by cooking/storage Typically work as part of enzymes in metabolism Relatively high absorption rate Severe deficiencies rare Vitamins – Niacin, Thiamine, Folic Acid, Riboflavin, B12, and C.

Enrichment Act of 1941 and 1998 Milling of rice, wheat, oats, etc… significantly reduces nutritional quality Whole grains contain original nutrients Enrich with thiamin, riboflavin, niacin, folate, iron Enriched grains still deficient in B-6, magnesium and zinc

Thiamin Destroyed by alkaline and heat Coenzyme: Thiamin pyrophosphate (TPP) Absorbed in the jejunum by a carrier-mediated system Transported by RBC in the blood Deficiency Beriberi Weakness, nerve degeneration, irritability, poor arm/leg coordination, loss of nerve transmission Edema, enlarge heart, heart failure

Food Sources of Thiamin Wide variety of food White bread, pork, hot dogs, luncheon meat, cold cereal Enriched grains/ whole grains Thiaminase found in raw fish 1.1 mg/day for women 1.2 mg/day for men Most exceed RDA in diet Surplus is rapidly lost in urine; non toxic

Riboflavin Coenzymes: Flavin mononucleotide (FMN) Flavin adenine dinucleotide (FAD) Oxidation-reduction reactions Electron transport chain Citric Acid Cycle Catabolism of fatty acids

Absorption, Transport, & Metabolism of Riboflavin HCL in the stomach release riboflavin from its bound forms Absorption Active or facilitated transport during low to moderate intake Passive absorption during high intake Increase with intake Transported by a protein carrier in the blood

Functions of Riboflavin Accepts electrons Electron Transport Chain FAD FADH 2 Succinate Fumarate Citric Acid Cycle Participates in beta oxidation FMN shuttles hydrogen ions and electrons to into the electron transport chain Metabolism of oxidized glutathione

Deficiency of Riboflavin Ariboflavinosis Glossitis, cheilosis, seborrheic dermatitis, stomatitis, eye disorder, throat disorder, nervous system disorder Occurs within 2 months Usually in combination with other deficiencies

Glossitis (Fig. 10-4) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Who is at Risk For Deficiency? Rare Low milk/dairy intake Alcoholics Long term phenobarbital use

Food Sources of Riboflavin Milk/products Enriched grains Liver Oyster Brewer’s yeast Sensitive to uv radiation (sunlight) Stored in paper, opaque plastic containers

RDA for Riboflavin 1.1 mg/day for women 1.3 mg/day for men Average intake is above RDA Toxicity not documented

Niacin Nicotinic acid (niacin) & nicotinamide (niacinamide) Coenzyme Nicotinamide adenine dinucleotide (NAD) Nicotinamide adenine dinucleotide phosphate (NADP) Oxidation-reduction reaction Metabolic reactions

Absorption, Transport and Storage of Niacin Readily absorbed from the stomach and small intestine Absorption: active transport and passive diffusion Transported from the liver to all of the tissues where it is converted to the coenzymes

Deficiency of Niacin Pellagra 3 Ds Occurs in days Decrease appetite & weight Prevented with an adequate protein diet Enrichment Act of 1941 Only dietary deficiency disease to reach epidemic proportions in the U.S. Who is at risk? (Untreated) corn as main staple, poor diet, Hartnup disease, alcoholics

Dermatitis of Pellegra (Fig. 10-5) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Food Sources of Niacin Mushroom Enriched grains Beef, chicken, turkey, fish Heat stable; little cooking loss 60mg tryptophan can be converted into 1 mg niacin

RDA for Niacin 14 NE/day for women 16 NE/day for men

Niacin as a Medicine x RDA can lower LDL and TG and increase HDL Slow/ reverse progression of atheroscelerosis with diet and exercise Toxicity effects Flushing of skin, itching, nausea, liver damage

Biotin Free and bound form Biocytin (protein bound form) Biotinidase in small intestine Metabolism of CHO, fat, protein (C skeleton) DNA synthesis

Functions of Biotin Assists in the addition of CO 2 to substances Carboxylation of acetyl-CoA to form malonyl-CoA for the elongation of a fatty acid chain Addition of CO 2 to pyruvate to yield oxaloacetate Breaks down leucine Allows 3 essential amino acids to be oxidized for energy

Food Sources of Biotin Cauliflower, yolk, liver, peanuts, cheese Intestinal synthesis of biotin Biotin content only available for a small number of foods Unsure as to bioavailablity of synthesized biotin We excrete more than we consume Avidin inhibits absorption > a dozen of raw eggs a day to cause this effect

Biotin Needs Adequate Intake is 30 ug/day for adults This may overestimate the amount needed for adults No Upper Limit for biotin

Who is at Risk For Deficiency? Rare High intake of raw egg white diet Alcoholics Biotinidase deficiency Anticonvulsant drug use Signs & symptoms: skin rash, hair loss, convulsion, neurological disorders, impaired growth in children

Vitamin B-6: Pyridoxal, Pyridoxine, Pyridoxamine Main coenzyme form: pyridoxal phosphate (PLP) Activate enzymes needed for metabolism of CHO, fat, protein Transamination Synthesis of hemoglobin and oxygen binding and white blood cells Synthesis of neurotransmitters

Deficiency of Vitamin B-6 Microcytic hypochromic anemia Seborrheic dermatitis Convulsion, depression, confusion Reduce immune response Peripheral nerve damage Who is at risk? Elderly Alcoholics Alcohol decreases absorption Destroy the coenzyme form

Food Sources of Vitamin B-6 Meat, fish, poultry Whole grains (not enriched back) Banana Spinach Avocado Potato Heat and alkaline sensitive

RDA for Vitamin B mg/day for adults 1.7 mg/day for men over mg/day for women over 50 Daily Value set at 2 mg Average intake is more than the RDA

Factors That Affect B-6 Requirement L -DOPA-medication used to treat Parkinson’s disease and Isoniazid-antituberculosis medication Reduce blood concentration of PLP Need extra vitamin B-6 Preeclampsia Reduce blood concentration of PLP Will supplementation will reduce preeclampsia?

B-6 As A Medicine? PMS B-6 to increase the level of serotonin Improve depression Not a reliable treatment Carpal tunnel syndrome Toxicity potential Can lead to irreversible nerve damage with > 200 mg/day

Folate (Folic acid, Folacin) Consists of pteridine group, para-aminobenzoic acid (PABA), and glutamic acid Coenzyme form: tetrahydorfolic acid (THFA)

Functions of Folate DNA synthesis Transfer of single carbon units Synthesis of adenine and guanine Anticancer drug methotrexate Homocysteine metabolism Neurotransmitter formation

Deficiency of Folate Similar signs and symptoms of vitamin B-12 deficiency Pregnant women Alcoholics Interferes with the enterohepatic circulation of bile/folate

Neural Tube Defects Spina bifida Anencephaly Importance of folate before and during pregnancy (Fig. 10-8) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Food Sources of Folate Liver Fortified breakfast cereals Grains, legumes Foliage vegetables Susceptible to heat, oxidation, ultraviolet light

RDA for Folate 400 ug/day for adults Daily Value is set at 400 ug

Vitamin B-12 Cyanocobalamin. methlcobalamin, 5-deoxyadenosylcobalamin Contains cobalt Folate metabolism Maintenance of the myelin sheaths Rearrange 3-carbon chain fatty acids so can enter the Citric Acid Cycle

Absorption of Vitamin B-12 (Fig ) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Functions of Vitamin B-12 Helps convert methylmalonyl CoA to succinyl CoA (citric acid cycle) RBC formation Nerve functions Maintains myelin sheath Megalobalstic anemia

Deficiency of Vitamin B-12 Pernicious anemia Never degeneration, weakness Tingling/numbness in the extremities (parasthesia) Paralysis and death Looks like folate deficiency Usually due to decreased absorption ability Achlorhydria especially in elderly Injection of B-12 needed Takes ~20 years on a deficient diet to see nerve destruction

Who is at Risk For Deficiency? Vegans Breastfed infants of vegan moms Elderly Individuals with AIDS or HIV

Food Sources of Vitamin B-12 Synthesized by bacteria, fungi and algae (Stored primarily in the liver) Animal products Organ meat Seafood Eggs Hot dogs Milk

RDA for Vitamin B ug/ day for adults and elderly adults Average intake exceeds RDA B-12 stored in the liver Non-toxic

Vitamin C Ascorbic acid (reduced form), dehydroascorbic acid (oxidized form) Synthesized by most animals (not by human) Absorbed by a specific energy dependant transport system Passive transport if intake is high Decrease absorption with high intakes Excess excreted

Functions of Vitamin C Reducing agent (antioxidant) Iron absorption Synthesis of carnitine, tryptophan to serotonin, thyroxine, cortiscosteroids, aldosterone, cholesterol to bile acids Immune functions Cancer prevention? Collagen synthesis

Collagen Synthesis (Fig ) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Antioxidant Can donate and accept hydrogen atoms readily Water-soluble intracellular and extracellular antioxidant Must be constantly enzymatically regenerated Needs are higher for smokers

Deficiency of Vitamin C Scurvy Deficient for days Fatigue, pinpoint hemorrhages Bleeding gums and joints. Hemorrhages Associated with poverty Rebound scurvy immediate halt to excess vitamin C supplements Who is at risk? Infants, elderly men Alcoholics, smokers

Food Sources of Vitamin C Citrus fruits Potatoes Green peppers Cauliflower Broccoli Strawberries Romaine lettuce Spinach Easily lost through cooking Sensitive to heat Sensitive to iron, copper, oxygen

RDA for Vitamin C 90 mg/day for male adults 75 mg/day for female adults +35 mg/day for smokers Average intake ~72 mg/day Fairly nontoxic (at <1 gm) Upper Level is 2 g/day Warning to people with hemochromatosis, oxalate kidney stones