Transcript VITAMINS
VITAMINS Chap 8 J Pistack MS/Ed Vitamins Organic substances—derived from living matter and contain carbon Small amounts required for normal metabolism, growth, and maintenance Coenzymes (substances that activate enzymes) and regulators of metabolic processes Do not provide energy Do not become part of body structure Specific functions nontransferable— deficiency diseases Vitamin Classifications Fat soluble (A, D, E, and K)—more stable to environmental influences; absorbed with fat; stored in body Water soluble (B vitamins and C)— less stable to environmental influences; only B12 stored for any length of time Vitamin A Chemical necessary for vision Health of epithelial tissue—skin, lining of gastrointestinal tract Normal bone growth Metabolism of adipose tissue Vitamins A preformed vitamin is already in a complete state in ingested foods A provitamin requires conversion in the body to become complete. A provitamin is also called a precursor because it is a substance from which another substance is derived Vitamin A Food Sources Preformed vitamin A—liver, egg yolk, fortified milk Provitamin A Carrots, sweet potatoes, squash Apricots, cantaloupe Spinach, collards, broccoli, cabbage Vitamin A Deficiency Diseases Night blindness Xerophthalmia - Extreme dryness and thickening of the conjunctiva, often resulting from a deficiency of vitamin A In developed countries, disease or lack of treatments can cause deficiencies Vitamin A Deficiency Vitamin A deficiency diseases in addition to vision: Anorexia Growth retardation Increased susceptibility to infection Disorders of the skin and hair follicles Taste impairment Balance disturbances Bone changes that impinge on cranial nerves (increased osteoblastic activity) Increased intracranial pressure Fertility Prevention and Treatment of Vitamin A Deficiency in Developing Countries Prevention Breastfeeding Supplementation Food fortification Diet diversification Treatment High-dose vitamin A Active corneal disease is a medical emergency Vitamin A Toxicity • Carotenemia - too many yellow vegetables; (squash and carrots) usually benign • Hypervitaminosis A - can be fatal • S/S similar to brain tumor • Liver disease Additional information: www.sightandlife.org Vitamin D Functions Increases intestinal absorption of calcium and phosphorus Stimulates bone cells to build tissue Signals kidney to return calcium to bloodstream, not excrete it in urine Vitamin D Deficiency Rickets—in children: still a risk, especially to dark- skinned breastfed infants Osteomalacia—in adults: low D intake and/or little sun exposure can cause a bone disease in adults analogous to rickets in children, marked by bone demineralization caused by impaired metabolism or deficiency of vitamin D or phosphorus. Disorders due to vitamin D excess One of the most likely vitamins to cause toxicity Loss of appetite Nausea/vomiting Polyuria Muscle weakness Constipation More serious issues consist of calcium deposits in the heart, kidneys, and brain Vitamin D Sources Sunlight on skin—daily sun exposure Arms, shoulders, and back without sunscreen Between 11 a.m. and 2 p.m. for 15 minutes in summer and 20 minutes in spring and fall Fortified foods—milk combines vitamin with calcium Supplements—cod liver oil vitamin/mineral supplement Vitamin E Functions Antioxidant - take on oxygen preventing surrounding molecules from becoming unstable Protects cell membranes (plays a role in vitamin E, provitamin A, and unsaturated fatty acids stability In lungs, barrier against air pollution Protects red blood cells from oxidation in lungs Vitamin E Deficiency Hemolytic anemia - Anemia resulting from the lysis of red blood cells Degenerative neurological problems Anemia in premature infants Vitamin E Toxicity Excessive supplemental vitamin E can cause Gastrointestinal symptoms Muscle weakness Double vision Increased bleeding tendencies Vitamin E Sources Vegetable oils—canola and olive oils highest in alpha-tocopherol (one of the components of vitamin E and is present in vegetable oils, nuts, and seeds or produced synthetically. It is the predominant form of vitamin E in the human body and in supplements.) Whole grains Especially fortified ready-to-eat cereals Wheat germ Nuts Leafy vegetables Vitamin K Functions Blood clotting—Necessary for the liver to make prothrombin and other clotting factors Bone metabolism—Facilitates synthesis of a calcium-binding protein (Osteocalcin) Vitamin K Note - Vitamin K can be given to serve as an antidote for warfarin overdose Vitamin K Deficiency Bleeding problems can occur in Newborns Long-term antibiotic therapy users People with malabsorption syndromes Vitamin K Sources Intestinal synthesis Varies from person to person Not sufficient as sole source Food sources—green leafy vegetables Broccoli, Brussels sprouts Cabbage, collards Salad greens, spinach Vitamin K Toxicity Not from naturally occurring forms Vitamin K1 (plants) Vitamin K2 (intestinal synthesis) Pharmaceutical K1 (phytonadione) not recommended intravenously except in emergency due to lifethreatening reactions Vitamin C Functions Collagen synthesis—strong, fibrous protein in connective tissue Antioxidant—more sensitive to oxidation than vitamins A and E Iron absorption—acts with HCl to keep iron in more absorbable form Aids in the synthesis of norepinephrine and serotonin Vitamin C Deficiency Signs and symptoms of scurvy Early—bleeding gums, petechiae (small hemorrhage) Late—delayed or reversed wound healing, bone pain and fractures, tooth loss, hemorrhage Treatment—vitamin C Current cases of scurvy Due to restricted eating patterns Delayed diagnosis due to low suspicion Vitamin C Sources Fruits—citrus, cantaloupe, kiwi fruit, papayas, strawberries Vegetables—broccoli, Brussels sprouts, green and red peppers Boiling, cooking, and canning fruits and vegetables lowers vitamin C content by 33% Vitamin C Toxicity S/S—nausea, abdominal cramps, diarrhea Megadoses contraindicated if at risk for Iron overload Kidney stones Thiamin Functions Coenzyme in metabolism of: Carbohydrates Glucose Branched chain amino acids Thiamin Deficiencies At risk Alcoholics People subsisting on milled rice Lack of glucose for central nervous system Wernicke encephalopathy—motor and sensory deficits involving eye muscles, balance, and memory Korsakoff psychosis—amnesia and impaired conceptual functions Thiamin Deficiencies Beriberi – broad classification of thiamin deficiency Dry beriberi – muscle weakness Wet beriberi – cardiovascular system culminating in right-sided heart failure Infantile beriberi – loud cry and convulsions Thiamin Sources Meat/legumes—pork, black beans, black- eyed peas Other plant sources—wheat germ, enriched grain products Fortified foods—cereals Riboflavin Function Coenzyme in metabolism of protein and other vitamins Deficiency Usually combined with other vitamin deficiencies like thiamin and niacin If alone it’s called Ariboflavinosis Niacin Function—coenzyme in energy metabolism Deficiency—pellagra 3 Ds—dermatitis (glove), diarrhea, dementia 4th D—death Sources of niacin—meat; fish; poultry; whole, enriched, or fortified grains; coffee; tea Vitamin B6 Function—coenzyme in the metabolism of amino acids Deficiency—rare except for drug interactions and food-processing errors Vitamin B6 Sources and Toxicity Sources of vitamin B6—widely distributed in foods, especially fortified beverages and cereals Toxicity None reported from foods Folate/Folic Acid Functions—necessary for the formation of DNA, thus participates in the reproduction of every cell Deficiency Link to neural tube defects (NTDs) - A group of birth defects that affect the backbone and sometimes the spinal chord. Discovery of this led to recent change in enrichment of grains Megaloblastic anemia Folate/Folic Acid Sources and Toxicity Sources of folate Liver, dried peas, beans, lentils Green leafy vegetables Fortified grains Toxicity of folic acid None reported from food or supplements Vitamin B12 Function and Deficiencies Functions—Required for Synthesis of DNA, RNA Metabolism of amino acids and fatty acids Synthesis and maintenance of myelin Deficiency Other pathology—gastric resection, gastric atrophy, Crohn’s disease Dietary causes—elimination of animal products Wise Use of Supplements Select a multivitamin/multimineral preparation Take recommended dosages, not to exceed 150% (one and one-half times) the RDA Mention when asked medication history