Lecture 6 - Vitamins PDF

Lecture #6 - Vitamins Chapter 7: page. 260 - 282 Chapter Learning Outcomes Describe Describe characteristics/functions of vitamins Distingu Distinguish fat-soluble, water-soluble & vitamin- ish like compounds Identify food sources, RDA/AI and health effects Identify relat...

Lecture #6 - Vitamins Chapter 7: page. 260 - 282 Chapter Learning Outcomes Describe Describe characteristics/functions of vitamins Distingu Distinguish fat-soluble, water-soluble & vitamin- ish like compounds Identify food sources, RDA/AI and health effects Identify related to vitamin deficiencies or toxicity List List antioxidant vitamins 2  What is a Vitamin? A complex organic compound that meets the following criteria: 1. The body cannot synthesize, or make enough, to maintain good health 2. Naturally occurs in common foods 3. Deficiency condition occurs when ___________________________ 4. Good health is restored, if deficiency disorder is treated early by supplying the missing substance 3  Most vitamins have more than 1 form ie. Vitamin A = retinol, retinal, Vitamins: retinoic acid Provitamins Basic Vitamin precursors that do not function in the body until Concepts converted to active forms Beta-carotene (plant pigment) = precursor to __________ Tryptophan = (amino acid) precursor to Niacin 4  Usually have more than 1 function in the body. Roles of Vitamins may act as: Hormones (ie. vitamin D) Vitamin Participate in chemical reactions (ie. Vitamin C or thiamin) Regulate cell division & s development Regulate growth & tissue maintenance Antioxidants (neutralize free radicals) 5 Vitamins & Their Function s 6 Classifying Vitamins 1. _____-Soluble: Associated with lipids in food and body Do not dissolve in water or urine and are stored in the body May reach toxic levels 2. _____-Soluble: Dissolve in watery components of foods and the body Excreted in urine, usually do not reach toxic levels Choline: vitamin-like compound 7  Source 1. Natural Sources. 2. Synthetic. s of 3. Enrichment. Vitamin 4. Fortification. s 8 Vitamin Absorption Most absorption occurs in small intestine Absorption is not 100% efficient Absorption generally increases when more of the vitamin is needed: Growth (e.g., during infancy and adolescence) Pregnancy Breast-feeding (milk production) 9 Vitamin Deficiency & Toxicity Disorders Deficiencies result from poor diets or certain health conditions In Canada, severe deficiencies are uncommon because of: Food preservation practices Food enrichment and fortification Widespread availability of fruits and vegetables Small % of some segments of the Canadian population consume inadequate amounts of certain vitamins 10 Fat-Soluble Vitamins A, D, E, K Fat-soluble vitamins  Vitamin A Names: Retinol (active form of vitamin A). Can be formed from provitamins (aka. Carotenoids). ie. beta-carotene. Recommended Daily Allowance (RDA): Retinol equivalents (R E), retinal activity equivalents (R A E), or international units. 1 R A E = 1 mcg retinol, 12 mcg beta-carotene, or 3.3 I U. R D A = 900 mcg R A E or 3,000 I U for adult males, 700 mcg R A E or 2,300 I U for adult females. 13 Sources & Functions Food Sources: Preformed vitamin A in animal foods: liver, butter, cheese, egg yolks, fish liver oils, and fortified milk. Beta-carotene in dark-green leafy and yellow-orange vegetables; some fruits. Major Functions Cellular Growth (epithelial cell maintenance) Vision (night and peripheral) Immune system function Bone Development Anti-oxidant (bet—carotene) 14  15 Vitamin A Content of Selected Foods Mmmmm….liver! Vitamin A Deficiency What is night blindness? The inability to see in dim light An early sign of vitamin A deficiency The retina (light- sensitive area inside each eye) contains rods & cones These are specialized nerve cells essential for vision Rods and cones need vitamin A to function properly 16  srxawordonhealth.com What is Carotenemia? Upper Limit: 3 mg/day Excessive consumption of vitamin A can damage the liver Signs/Symptoms: headache, nausea, vomiting, visual disturbances, hair loss, bone pain/fractures Teratogenic effects may occur Carotenemia: Yellowing of skin due to excessive beta-carotene intake Appears to be both reversible and harmless 17 Vitamin D Names: Vit D2 = Ergocalciferol Vit D3 = Cholecalciferol Dietary Adequacy Infants 0 to 12 months: AI = 10 mcg cholecalciferol or 400 IU. 1 to 70 years old: AI = 15 mcg or 600 IU. >70 years: AI = 20 mcg or 800 IU. UL for those over 9 = 100 mcg or 4,000 IU. Vitamin D Toxicity Too much calcium is absorbed Excess calcium is deposited in soft tissues 18 including kidneys, heart, and blood vessels Sources & Functions Food Sources: Fatty fish (salmon, mackerel, sardines, and catfish) contain 200–500 I U in 3 oz. Shitake mushrooms contain 250 I U in four mushrooms. Small amounts in egg yolks and butter. Fortified foods (milk, cereals, orange juice). *Typically get about 90% of Vitamin D from sunlight, 10% from food Major Functions Bone Metabolism Calcium & Phosphorus metabolism & absorption (SI & kidneys) Parathyroid Hormone (PTH) Released when blood calcium levels drop Stimulates kidneys to increase active vit D production & decrease urinary calcium excretion Muscle Function 19 Activatio n of Vitamin D 20 Maintenance of Normal Calcium Levels 21 Vitamin D and Sunlight People who live south of the 37th parallel and are outdoors when sunlight is most intense will likely synthesize adequate vitamin D most of the Year *Barrie is 44.39 degrees North 22 Deficiency Vitamin D Deficiency Rickets: Softening/weakening of bones Rare in the Canada because many foods are fortified with vitamin D Osteomalacia - “adult rickets” Muscle weakness (impaired calcium metabolism in muscle) Other Potential Issues: Increased risk of myocardial infarction Increased risk of insulin resistance/diabetes Increased blood pressure Increased risk of poor cognitive function & Alzheimer’s disease Vitamin E – Alpha-tocopherol Dietary Adequacy RDA =. 1 mg = 1.5 IU. UL =. Deficiency Hemolysis: “breaking apart” of red blood cells Due to oxidation of polyunsaturated fatty acids in cell membrane Toxicity Upper Limit (UL) - Excess intake may interfere with vitamin K’s role in blood clotting 24 Sources & Functions Food Sources: Polyunsaturated vegetable oils. 1 tablespoon contains about 5 mg. Sunflower seeds, almonds, peanuts, wheat germ, and several vegetables are also good sources. ¼ cup sunflower seeds contains about 8 mg. ½ cup cooked spinach contains about 2 mg. Meats, refined grains, and dairy foods are typically poor sources. Major Functions Antioxidant in the cell membrane Prevent oxidation of cell phospholipids & vitamin A Role in synthesis of hemoglobin Improve cellular O2 utilization (in mitochondria) Maintains nervous system and immune system function 25 Selected Food Sources Vitamin E 26 Vitamin K Names: Phylloquinone—plant form. Menaquinone—animal form. Menadione—synthetic form. Dietary Adequacy AI = ___________ for adult males and females. No UL has been established. Deficiency Uncommon May cause impaired blood clotting & hemorrhaging 27  Food Sources: Plant foods: vegetable oils; green Sources leafy vegetables: Main dietary source. & 3 oz spinach contain 380 mcg. Animal foods: meats and milk: Lower concentrations. Functio 3 oz meat contain less than 1 mcg. Synthesis in body: ns Intestinal bacteria form menaquinone. Major Functions Formation of compounds for blood clotting May play a role in strengthening bones 28 Water Soluble Vitamins B-Complex, C Water-soluble vitamins  _____ vitamins: Vitamin B complex Water- Vitamin C (ascorbic acid). Not stored in the body. soluble Excess is excreted in urine. Deficiency symptoms may be vitamin noted in 2 to 4 weeks. May reduce physical performance capacity. s Most act as components of coenzymes necessary for energy metabolism.  Most water-soluble vitamins function as components of specific Coenzyme coenzymes Coenzymes: s small molecules that regulate chemical reactions by interacting with enzymes 32 B1 Dietary Adequacy RDA = ___ mg/day (men) ___ mg/day (women) Deficiency Deficiency symptoms can occur within in a few days _______: life-threatening thiamin-deficiency condition Can result in muscle wasting, edema, heart problems, memory loss Most common in 3rd world countries or alcoholism (decreases thiamin absorption) Functions Part of coenzyme involved in release of energy from carbohydrates Nervous system function Energy derivation form muscle glycogen 33 Food sources Widely distributed in plant and animal foods. Whole grain cereals, beans, pork. One lean pork chop contains 50 percent of the R D A. Several fortified, ready-to-eat cereals contain _____ percent of the RDA for thiamin, as well as most of the other B vitamins. Selected Food Sources of Thiamin 35 B2 Dietary Adequacy RDA = ____ mg/day (males) ____ mg/day (females) Deficiency Glossitis (inflammation of the tongue), skin cracking, scaly skin Confusion and headaches Functions Coenzyme for metabolism of carbohydrate, lipids, and amino acids Synthesis or conversion of vitamins Vit A & Folate  active forms Tryptophan  Niacin 36 Food sources Widely distributed in plant and animal foods. Milk and dairy products riboflavin quickly degrades with light; do not store in clear glass containers Liver, eggs Dark-green leafy vegetables Wheat germ, yeast Whole-grain products, enriched breads and cereals Selected Food Sources of Riboflavin 38 B3 Dietary Adequacy RDA = __ to __ mg/day UL = 35mg/day Deficiency _______ (the “4 D’s”) Dermatitis, Diarrhea, Dementia, Death Functions Important for glycolysis and fatty acid & amino acid metabolism Aerobic & Anaerobic energy processes 39 Selected Food Sources of Niacin 40 B5 Dietary Adequacy: ___ mg/day Deficiency is rare (B5 found in almost all foods) ”Burning Feet Syndrome” Tingling sensation in LE, fatigue, weakness, nausea Functions Coenzyme for a variety of metabolic reactions (glucose, A.A.s, fatty acids) 36  Dietary Adequacy B6 RDA = ___ to __ mg/day UL = ___ mg/day Deficiency rarely occurs, but signs and symptoms include: Dermatitis Anemia Convulsions Depression Confusion Functions Part of coenzyme needed for 42 Selected Food Sources of B-6 43 B7 Dietary Adequacy ___ micrograms/day Deficiencies May be caused by genetic disorders or smoking S/S: depression, infections, hair loss, seizures Functions Component of coenzymes involved in energy metabolism pathways 39 B9 Dietary Adequacy RDA = ___ mcg DFE/day Pregnancy = ____ DFE/day Deficiency Affects cells that rapidly divide: ie. RBCs (megaloblastic, macrocytic anemia) Mature RBCs do not have nuclei and live -4 months Without folate RBC precursor cells enlarge, but cannot divide Bone marrow releases some large, immature abnormal red blood cells with nuclei (megaloblasts) into the blood stream, a condition referred to as macrocytic anemia = megaloblastic anemia Can lead to Spina Bifida Type of malformation of fetal neural tube during pregnancy 45  Assists in red blood cell production Part of coenzyme tetrahydrofolic acid Folate - (THFA) Functions THFA is involved in DNA and amino acid metabolism Conversion of homocysteine to the essential amino acid methionine sources Green leafy vegetables, like spinach. Organ meats like liver and kidney. Whole grains, legumes. Fruits (oranges, bananas, avocadoes and papayas) Fortified grains (average 140 mcg/100 grams of food). Selected Food Sources of Folate 48 Neural Tube Defects During the first few weeks after conception, the neural tube forms Folate-deficient pregnant women are at risk of giving birth to infants with neural tube defects Common types: Anencephaly: Spina bifida: 49  Dietary Adequacy B12 ____ micrograms/day Deficiency Pernicious Anemia: genetic defect reduces production of intrinsic factor. Results in poor B-12 absorption S/S: Megaloblastic anemia, nerve damage, weakness, sore tongue, memory loss, confusion, difficulty walking and maintaining balance, and eventual death 50 Vitamin B-12 Functions Part of coenzymes required for folate metabolism and maintenance of myelin sheaths Important role in RBC formation Sources Only found in animal foods: meat, fish, poultry, cheese, eggs, and milk. Supplementation recommended for vegans Found in fortified foods, such as breakfast cereals. 51 Selected Food Sources of Vitamin B-12 52  Aka. ___________ Dietary Adequacy Vitamin RDA =___ to ____ mg/day (higher for smokers) Deficiency C ________: rare in Canada; prevented by 10mg/day S/S: poor wound healing, pinpoint hemorrhages, bleeding gums, bruises, depression Toxicity UL= ______ mg/day Kidneys excrete excess amounts of the vitamin and oxalate, a byproduct of vitamin C metabolism Excess oxalate excretion increases risk of kidney stones, particularly in susceptible persons 53 Vitamin C – Functions Not part of a coenzyme, but serves as a nutrient cofactor that facilitates several chemical reactions: 1. Collagen synthesis Participates in reactions that form and maintain collagen, by strengthening cross-connections between amino acids 2. Antioxidant activity Can act as an antioxidant by donating electrons to free radicals 3. Other Roles Immune system functioning Synthesis of bile, and certain neurotransmitters and hormones 54 Selected Food Sources of Vitamin C 55 Chloine Dietary Adequacy: A I = ___ mg/day males; ___ mg/day females. U L = ___ grams/day. Deficiency: Deficiency is very rare. Experimental deficiency: Fatty liver and liver damage. Food Sources: Animal foods as lecithin; plants as free choline. Milk, liver, and eggs are good animal sources. Good plant sources include vegetables, legumes, nuts, seeds, and wheat germ. Functions: Precursor for lecithin, a phospholipid in cell membranes. Involved in the formation of acetylcholine, an important neurotransmitter. Preserving Vitamin Content of Foods Better source of vitamins: Fresh or Frozen/Canned? Depends on 2 main factors:.. Vitamins susceptible to loss: Vitamin C, Thiamin, Folate More stable vitamins: Niacin, Vitamin D 57 Maximize Vitamin Contents of Foods Avoid buying wilted, bruised, or shriveled produce Store at near freezing temperatures, in high humidity and air-tight containers Cook in small amounts of water Use quick cooking methods such as microwaving, steaming, and stir- frying Freeze produce to preserve vitamins 58  Vitamins occur Have wide range of naturally in roles/functio foods ns Recap A D E K vs. Water Soluble B-Complex vs. Fat Soluble &C Disorders can Scurvy, result from Pellegra, deficiencies Spina Bifida