Lect14+WaterSol+Vitamins - Why do we need to eat...

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Unformatted text preview: Why do we need to eat Vitamins? !  Lack ability to make essential chemicals !  Prevent deficiency !  Prevent birth defects •  Improve Health? Slow Aging?????? •  Should we treat the symptom: “low vitamin status”? •  Or treat the underlying cause: the need for a complete diet?? Absorption of Vitamins water soluble vitamins not stored in body fat soluble stored in body Loss of Vitamins during Food Preparation •  Exposure to oxygen, heat or light •  Leach out into cooking water •  Milling of grains –  Grain/cereal products enriched with: Folate, Thiamin, Riboflavin, Niacin, Iron –  Still lack Fiber, trace minerals Vitamins act as Cofactors for enzymes boiling reduces vitamins in vegetables refined grains loses vitamins vitamins with bind to enzyme (incomplete) to make a functional enzyme amount of enzyme is the limiting factor 1 Role of Vitamins in Energy Metabolism Folate -- Folic Acid •  Function: Synthesis of DNA, RNA, amino acids Converts Vitamin B12 to active form •  Food sources: foliage, green vegetables, grains, legumes, Fortified breads & cereals Folate/B12 Deficiency: Folate Deficiency •  •  •  •  Megaloblastic anemia Spina Bifida GI tract deterioration Anti-folates given as cancer drugs: e.g. Methotrexate: stops cell division Megaloblastic Anemia A nti-folates inhibits cell growing cells are large and dark does not have oxygen carrying capacity folic acid would work ONLY if it's folate d eficiency anemia (does not work for Iron d eficient anemia, ) 2 Folate Deficiency: Spina Bifida: incomplete closure of neural tube Vitamin B12 Function: •  Folate metabolism •  Formation of myelin sheath Absorption: •  Stomach: secretes Intrinsic Factor •  Intestine: B12 -Intrinsic Factor Complex absorbed Food Sources: Animal products B12 synthesized ONLY by bacteria Folate must be given BEFORE pregnancy to prevent spina bifida sometimes permanent paralysis neurotube does not close b irth defects folate deficiency declined dramatically when flour was fortified with folate need b12 for folate metabolism Natural B12 is only by bacteria inside of animals Pernicious Anemia Nerve damage PLUS megaloblastic anemia B12 deficiency due to •  Lack of intrinsic factor: autoimmune disease or bariatric surgery •  Malabsorption disorders •  May take 5-15 years to develop •  •  •  •  Thiamin Riboflavin Niacin Vitamin B6 B Vitamins: 1. Function as coenzymes (cofactors) 2. Participate in energy metabolism 3. 50-90% are absorbed Nerve damage is irreversible Store a fair amount of B12 (5-15 years) First symptom of B12 deficiency is anemia 3 Thiamin Deficiency: Beriberi –  First seen with advent of polished rice Riboflavin Function: Cofactor Food sources: milk, dairy Light-sensitive: milk in opaque containers Symptoms: •  Damage to nervous system, heart •  Common in alcoholics Food sources: pork, enriched grains Niacin Deficiency: Pellagra Diarrhea, dermatitis, dementia, death Usually in people consuming low protein, corn-based diets. Common in certain parts of the world. Function: 1. Coenzyme for formation of: •  collagen: framework of bone, skin, gums •  Neurotransmitters •  Hormones •  Bile acid synthesis Vitamin C common in people low with tryptophin 4 Scurvy Vitamin C Corkscrew hair Pinpoint hemorrhages Function: 2.  Antioxidant – water soluble •  Stabilizes free radicals by donating their electrons or hydrogen •  protects LDL & white blood cells •  Regenerates oxidized Vitamin E 3. Enhances absorption of Iron Gingival hemorrhage Periungual hemorrhage Free radicals •  Unstable molecule with an unpaired electron –  created during the processing of oxygen Do we need additional antioxidants for exercise? o  Recent study: supplements of Vit C and E blocked improved insulin sensitivity due to exercise o  Not known: whether exercise-induced free radical damage occurs o  Body adapts to exercise: produces more antioxidant defenses o  No evidence that athletes have negative health effects. •  Can react with other molecules to form more free radicals, leads to chain reaction –  E.g. damaged cell membranes, DNA 5 ...
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