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The Vitamins Introduction Vitamins were discovered at the beginning of the twentieth century. Vitamin: An essential, noncaloric, organic nutrient needed in tiny amounts in the diet. A vitamin can cure a deficiency of that vitamin Classifying Vitamins Fat A D E K Soluble Vitamins Water Soluble Vitamins Vitamin C B Vitamins: Thiamin -- Biotin Riboflavin -- Pantothenic acid Niacin B6 Folate (folic acid) B12 Water Soluble Vitamins Digestion, Absorption, and Transport No chemical digestion needed Absorbed in the SI into the capillaries • Vitamin B12 must bind with a protein called the intrinsic factor (IF) in the stomach for absorption to occur in the SI No carriers required for transport in the blood Water Soluble Vitamins Storage and excretion Travel freely in the blood Cells take up water soluble vitamins as needed • Limited storage beyond tissue saturation Excess excreted in the urine Water Soluble Vitamins Deficiency is more common than toxicity for the water soluble vitamins Any toxicity is likely to be due to overuse of vitamin supplements, not food intake Water Soluble Vitamins Other interesting information: Many are destroyed by light, heat, or exposure to oxygen Best to cook whole in a minimum amount of water Frozen vegetables are often higher in vitamin content than grocery store “fresh” veggies • The Fat-Soluble Vitamins A, D, E, K Found in fats and oils of foods Require bile for absorption Stored in liver and fatty tissues until needed Not needed in the diet daily Can reach toxic levels if too much is consumed Deficiencies can occur when people eat diets that are extraordinarily low in fat Fat Soluble Vitamins Digestion, Absorption, and Transport Bile needed to emulsify fat soluble vitamins Form chylomicrons (along with long chain fatty acids and monoglycerides) Chylomicrons are absorbed into the lacteals Travel through lymph system blood liver Many require protein carriers to be transported in the blood Fat Soluble Vitamins Other interesting facts: Found in the fatty parts of food Removed with the fat when low-fat products are made • Many low-fat foods are supplemented with these vitamins to make up for this E.g. milk is vitamin A and D enriched Other interesting vitamin cooking/storing facts – page 293 The Vitamins For each vitamin we will consider: Functions Dietary needs and food sources Deficiency Toxicity The B- Vitamins: An Introduction Thiamin, riboflavin, niacin, pantothenic acid, and biotin – participate in the release of energy from the energy nutrients Folate and vitamin B12 help cells multiply Vitamin B6 helps the body use amino acids to synthesize proteins B Vitamin Deficiencies In a B vitamin deficiency, every cell is affected. Symptoms include • • • • • • • Nausea Severe exhaustion Irritability Depression Forgetfulness Loss of appetite and weight Impairment of immune response • • • • • Abnormal heart action Skin problems Swollen red tongue Teary, red eyes Pain in muscles Thiamin History Functions: 1. Needed for energy metabolism • 2. E.g. -- required for conversion of pyruvate to acetyl CoA Needed for nerve and muscle function Thiamin Recommended Intake 1.1-1.2 mg/day Food Sources Found in small amounts in many foods Easily destroyed by heat (cooking) Lost in cooking water Good sources include • Pork products, soy, legumes, vegetables, whole grains, watermelon…. Page 311 Thiamin Deficiency Prolonged deficiency leads to beriberi Results in damage to nervous system and muscles (to include the heart) Thiamin Deficiency Symptoms Beriberi: 1. Dry form- muscle wasting, poor coordination Muscle weakness 2. Legs heavy, hard to walk, calf pain 3. Apathy, confusion, memory loss 4. Anorexia and weight loss 5. Wet form has additional symptoms of: – edema, irregular heart beat, enlarged heart Thiamin Deficiency Thiamin Deficiency Populations at risk: Alcoholics • Often obtain the majority of their calories from alcohol • Alcohol inhibits thiamin absorption and hastens its excretion Cultures that eat primarily refined grains (e.g. white rice) and little else Thiamin deficient moms infant deaths from deficiency In alcoholics thiamin deficiency results in Wernicke-Korsakoff syndrome. Even if someone who drinks alcohol heavily follows a wellbalanced diet, most of the thiamine is not absorbed. Symtpoms • Mental confusion • Staggering • Rapid eye movements or paralysis of the eye muscles The City of New York DEPARTMENT OF HEALTH AND MENTAL HYGIENE Michael R. Bloomberg Thomas R. Frieden, m.d., m.p.h. Mayor Commissioner _______________________________________________________________ nyc.gov/health 2003 Health Alert # 39: A cluster of infantile thiamine (vitamin B1) deficiency (beri-beri) has been reported in Israel among infants fed a vitamin B1-deficient kosher soy-based formula distributed by Remedia. It is possible that this product may be imported into New York City and there may be children in the Orthodox Jewish community who have consumed it. The New York City Department of Health and Mental Hygiene (NYCDOHMH) asks that providers report immediately any suspect case of thiamine deficiency among infants who have been fed this product to: The New York City Poison Control Center at: 1-212-764-7667 (212-POISONS) or 1-800-222-1222. Please distribute to Pediatric staff in the Departments of Cardiology, Critical Care, Emergency Medicine, Family Medicine, General Pediatrics, Outpatient Pediatrics, Neonatology, Neurology, and Infectious Disease Thiamin Toxicity None known Excess thiamin is excreted and not stored Riboflavin Functions: 1. Needed for the metabolism of carbohydrates, fats, and proteins • • 2. Places a role in Kreb’s cycle Part of FAD This text includes an antioxidant function as well….most do not consider riboflavin an anti-oxidant Riboflavin Recommended Intake: 1.1 – 1.3 mg/day Food Sources: Destroyed by ultraviolet light (sun light) Good sources include (page 313) • • • • • Whole grain breads and cereals, oatmeal Liver Milk and milk products Clams and squid! Mushrooms Riboflavin Deficiency Symptoms 1. 2. 3. 4. 5. 6. Eyes are inflamed and sensitive to light Cheliosis (cracks at the corners of the mouth) Sore throat Inflammation of the tongue and mouth – painful Inflamed skin, with lesions covered with greasy scales Anemia page 312 Riboflavin Populations at Risk for Deficiency alcoholics any one with a marginal diet • Poor, elderly, eating disorders, drug addicts… Toxicity None reported Excess excreted Niacin Functions 1. Plays an essential role in energy metabolism • • Part of NAD Needed by every cell of the body Niacin Recommended Intake: 14 – 16 mg/day of niacin or of NE NE = Niacin Equivalents • Niacin can be made from the essential amino acid tryptophan • It takes 60 mg of tryptophan to make 1 mg of niacin • Therefore, 1 NE is 60 mg of tryptophan Niacin Food Sources (page 315): Sources of complete protein • Dairy, meats, poultry, fish,… Peanut butter Tomato paste Mushrooms Niacin Deficiency Niacin deficiency disease is called pellagra Symptoms, 4 D’s: 1. 2. 3. 4. Dermatitis especially with sun exposure Diarrhea, vomiting Dementia Death Other symptoms: 1. Inflamed, swollen, red, smooth tongue 2. Loss of appetite 3. Page 314 Niacin Pellagra symptoms: 4 “D’s” Diarrhea Dermatitis Dementia Death Niacin Pellegra - Other interesting information Originally believed to be caused by infection Common up to early 1900’s in US and Europe • Many in mental hospitals in south had niacin deficiency, not mental illness Incidence declined in US after WW II when mandatory enrichment of grains began Still common in Africa and Asia • Poor bioavailability form corn unless it’s soaked in lime juice Niacin Toxicity Tolerable Upper Intake Level (UL) = 35 mg/day High doses of niacin are commonly used to treat high cholesterol • 1500 -3000 mg/day recommended for treating high cholesterol Niacin Toxicity Symptoms 1. 2. 3. 4. 5. Niacin flush Excessive sweating Tingling GI distress Frequent need to urinate • 6. 7. May mask prostrate cancer symptoms in men Blurred vision, headaches Liver damage Folic Acid = Folate Functions: 1. Needed for DNA synthesis • • 2. Need to make all new cells E.g. Need to make new RBC Reduces incidence of neural tube defects • Defects occur in first weeks of pregnancy Folate 3. 4. Plays a role in protein synthesis Breaks down the amino acid homocysteine – High levels of homocysteine increases risk of blood clot formation 5. May reduce risk some cancers – Pancreatic cancer in men who smoke – Breast cancer in women who drink Folate Absorption and Activation Folate in foods must be acted upon by an intestinal enzyme for it to be absorbed and transported to cells Folate in cells needs to be activated by vitamin B12 • Process also activates the B12 Folate Recommended intake: 400 mcg/day Factors impacting needs Pregnancy -600 mcg/day Aspirin, antacids, smoking, oral contraceptives reduce absorption Some cancer drugs reduce absorption GI tract damage reduces absorption • Occurs with alcoholism, anorexia • Poor absorption, leads to even more damage to GI tract Folate Food Sources Cooking destroys up to 50% of folate Oxygen destroys folate Good sources include (page 323): • • • • • • Green leafy vegetables Asparagus Legumes Fortified cereals and Seeds Liver Orange juice (ok, but not great source) Folate Folate Deficiency (page 321) Impairs cell division and protein synthesis Symptoms: 1. Megaloblastic anemia Fewer red blood cells (RBC) made RBC larger than normal RBC do not carry oxygen as well Folate Deficiency 2. Confusion, irritability, weakness, fatigue • 3. 4. 5. 6. Related to the anemia GI tract deterioration Elevated homocysteine levels Smooth red tongue Increased risk neural tube defects Folate Toxicity No known symptoms May mask a vitamin B12 deficiency • B12 deficiency is VERY serious Vitamin B12 Dorothy Crowfoot Hodgkin Awarded the Nobel prize in chemistry for deducing the structure of vitamin B12 • Took her eight years Headline in the London paper announcing this read “Nobel Prize for British Wife” Vitamin B12 Functions: Needed to activate folate • Therefore, needed for DNA and new cell (RBC) synthesis Helps maintain myelin sheath around nerve cells Vitamin B12 Recommended intake: 2.4 microgams per day Food Sources*: ONLY found naturally in animal products • Meat, poultry, fish, eggs, dairy, liver…. Fortified grains *Easily destroyed by microwave cooking Vitamin B12 Deficiency: Pernicious anemia (VERY SERIOUS) • • • • Megaloblastic anemia Nerve damage creeping paralysis Smooth sore tongue Fatigue Vitamin B12 Vitamin B12 Pernicious anemia frequently goes undiagnosed Pernicious anemia can be masked by high intakes of folate Generally as supplements B-12 and Folate Presence of immature red blood cells symptom of folate or vitamin B12 deficiency Extra folate corrects this blood condition B12 deficiency continues B12’s other functions then become compromised Vitamin Vitamin B12 Gastric by-pass patients and vegans are at elevated risk Takes several years to develop Toxicity: None reported B6 Functions: Need for protein and fatty acid metabolism Need for amino acid metabolism • E.g. For converting tryptophan to other niacin • need to make serotonin form tryptophan Helps make RBC Other functions under study B6 Recommended Intake: 1.3 mg/day UL: 100 mg/day Food sources (page 318): destroyed by heat Meat, fish, poultry Legumes Seeds and nuts Liver Non-citrus fruits B6 Deficiency: (rare) Anemia Weakness and fatigue Depression, confusion Abnormal brain waves, convulsions Greasy dermatitis B6 Increased risk of deficiency: Alcoholics • Alcohol contributes to increased B6 breakdown and excretion Oral contraceptives may increase risk of B6 deficiency Drug INH inactivates B6 INH used to treat tuberculosis B6 Toxicity: Serious Stored in muscle cells, toxicity seen with supplements Symptoms: • Irreversible nerve damage numbness in hands and feet Difficult to walk • Convulsions • Insomnia, restlessness B6 B6 does not help with: Carpal tunnel syndrome PMS Supplementation above the UL is NOT recommended Biotin Functions: Need for energy metabolism Need to make glycogen Plays a role in fatty acid and amino acid synthesis Biotin Recommended Intake: 30 micrograms/day (AI) Food Sources*: Widespread in foods: liver, egg yolk, legumes, fish, mushrooms, whole grains… Some produced by GI tract bacteria *easily destroyed by processing Biotin Deficiency: RARE • • • • • Skin rash Hair loss Depression Hallucinations Numbness in legs/arms Biotin Deficiency can be induced by eating LARGE quantities of raw egg whites 2 dozen daily for ~2 months! Prevents biotin absorption Toxicity: none reported Pantothenic Acid Functions: Need for energy metabolism • Part of acetyl CoA Plays a role in the synthesis of many substances: • • • • Lipids Hormones Neurotransmitters Hemoglobin Pantothenic Acid Recommended intake: 5 mg/day (AI) Food Sources: Widespread in foods Pantothenic Acid Deficiency: Rare Fatigue GI distress Insomnia, depression Apathy, irritable Increased sensitivity to insulin Toxicity: none known Vitamin C Functions: Collagen synthesis • Part of scar tissue • Strengthens blood vessels • Provides matrix for bone growth Antioxidant Need for healthy immune system Need for thyroxine production Vitamin C Functions: Need for thyroxine production • Regulates body temperature and metabolic rate Enhances iron absorption Need to make hemoglobin Vitamin C Recommended intake: Men: 90 mg/day Women: 75 mg/day Smokers: an extra 35 mg/day • More free radicals that need to be “neutralized” UL: 2000 mg/day Vitamin C Food sources* (page 329): Citrus fruits Strawberries, melon Vegetables • Tomatoes, dark green leafy vegetables, potatoes, broccoli… *Heat and oxygen sensitive Vitamin C Deficiency: Scurvy Poor wound healing - Increased infection Weakness Bleeding gums Loose teeth Broken blood vessels Loss of appetite Joint pain and fragile bones Anemia Deficiency Symptoms Vitamin C Populations at increased risk: Alcoholics Elderly Babies and toddlers fed only milk/cereals Smokers After illness or stress • Fever and stress deplete vitamin C stores Vitamin C Toxicity Symptoms: Diarrhea Cramps, nausea Headaches, insomnia May interfere with lab tests and meds Increased risk kidney stones Over-absorption of iron Fat Soluble Vitamins A D E K Vitamin A Chemical nature: Active forms of vitamin A • Retinol • Retinoic acid • Retinal Precursor form • Beta-carotene • Converted to active vitamin A as needed Vitamin A plays a role in • Gene expression • Vision • Maintenance of body linings and skin Need to build healthy epithelial and mucous tissue • Immune defenses • Growth of bones and of the body • Normal development of cells Plays a role in cell differentiation • Reproduction Vitamin A - Functions Vitamin A plays two roles in eye sight: Process of light perception at the retina Maintenance of a healthy cornea Beta-Carotene Functions beta-carotene; Can be converted to active vitamin A as needed Antioxidant Vitamin A Recommended intake: 700-900 RAE micrograms/day RAE = retinol activity equivalents • Older unit is IU = International Units UL 3000 RAE • UL refers to active vitamin A only, not betacarotene Vitamin A Food Sources pre-formed Vitamin A: All animal sources • • • • • In fatty portion of the food Dairy products Eggs Meat, liver Fortified skim milk and margarine • Page 296 Beta-Carotene Food Sources beta-carotene: All plant sources Yellow/orange/red fruits and vegetables • Carrots, apricots, cantaloupe, mangos, pumpkin, sweet potato, winter squash, peppers…… Dark green leafy vegetables • Spinach, kale, broccoli, beet greens (but not the beet!) Vitamin A Deficiency Symptoms – eye sight related Night blindness Blindness • Leading cause of blindness worldwide • ~ ½ million children go blind each year due to a vitamin A deficiency Eyesight Vitamin A Deficiency: Keratinization dry, cracked skin Reduced secretions • GI tract • Bladder • Lungs Above symptoms increase risk of infection Skin And Body Linings The skin in vitamin A deficiency Vitamin A Deficiency: Anemia Slow bone growth Painful joints Cracked, cracked teeth Delayed sexual maturity Vitamin A Toxicity: Teratogenic • “monster producing” GI distress, weight loss Bone issues • Joint pain • Stunted bone growth and more Vitamin A Toxicity: Headaches, pressure inside skull Blurred vision Fatigue, muscle weakness Skin rashes Dry, cracked, bleeding lips Dry, brittle hair Vitamin A Vitamin A toxicity can be fatal Symptoms go away quickly if diet changes Toxicity is never from beta-carotene sources Beta-carotene toxicity….. Vitamin D Chemical nature: Vitamin D is a sterol Body can make from cholesterol – see page 299 • Requires sunlight exposure, action of skin, liver, and kidney Vitamin D Functions: Bone mineralization • Works with other nutrients Vitamins A, C. K Several minerals Regulates calcium and phosphorus levels • Stimulates Ca and P absorption in SI • Regulates movement of Ca and P in/out of bones • Stimulates kidneys to retain Ca and P All of the above are related to bone mineralization Vitamin D Other Functions: Acts as a hormone • Not fully understood • Many target organs: Brain and CNS Muscle Reproductive cells… Vitamin D Recommended intake: Depends upon sun exposure and skin color 5-10 micrograms/day (AI) UL: 50 mcg/day Vitamin D Food sources* (page 301): Fortified milk and margarine Butter Egg yolks Liver Fatty fish and fish oils *natural sources are all animal sources Vitamin D Deficiency: Bone abnormalities • Kids rickets • Adults osteomalcia Vitamin D Populations at risk for deficiency: Inner-city kids Dark skinned Live in a northern climate Limited sun exposure Elderly Kidney or liver disease Vegans Vitamin D Toxicity: Very toxic • Can be lethal • Milk story Toxicity is never from sun exposure Vitamin D Toxicity Symptoms: Calcium deposits in soft tissue • Muscles, lungs, heart Kidney stones Calcium deposits on walls of arteries Joint pain Frequent urination GI distress Vitamin E Chemical nature: A type of tocopherol 4 forms • Alpha, beta, gamma, delta • Alpha-tocopherol is the most active form • Other forms have very limited bioactivity Vitamin E Functions: Antioxidant • Component of animal cell membranes • Protects unsaturated fatty acids in cell membranes Other roles are not clearly defined, but likely exist Vitamin E Recommended intake: 15 mg/day Need more if eat more polyunsaturated fats most students did not meet their vitamin E requirement on the day analyzed Vitamin E Food sources* (page 303): Vegetable oils Nuts and seeds Whole grains Green leafy vegetables Liver Wheat germ Egg yolks *easily destroyed by heat and oxygen Vitamin E Deficiency: Rare as most vitamin E is recycled See in premature babies • Transferred from mom to baby in last weeks of pregnancy Cystic fibrosis patients • Due to poor fat absorption Vitamin E Symptoms deficiency: Hemolytic anemia • RBC break open Neurological problems with prolonged deficiency • Loss of coordination • Vision and speech problems • Does not prevent/cure MD Vitamin E Vitamin E may help with: Leg cramps • Intermittent claudication Fibrocystic breasts disease • “lumpy” breasts Vitamin E Toxicity: Rare Supplements recommended by many, but not above the UL = 1000 mg • 200 mg supplement probably enough May interfere with blood clotting • Stop taking supplements prior to surgery Other symptoms: nausea, fatigue, blurred vision VITAMIN K Functions: Need for synthesis of blood clotting proteins Plays a role in regulation of calcium levels Vitamin K Recommended intake: 90-120 mcg/day Sources: Made by GI tract bacteria Dark green leafy vegetables, cabbage family Liver Milk Vitamin K Deficiency: rare Symptoms: • Bleeding, hemorrhaging • Bone weakness Populations at risk • Babies • After long-term antibiotic treatment • CF Vitamin K Toxicity: rare Occurs with supplement overuse • Take with caution, even if prescribed Symptoms: • • • • RBC break open Jaundice Brain damage Interferes with anti-clotting meds