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PHAR 100 (175)
Lecture

27vitamins.pdf

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Department
Pharmacology and Toxicology
Course
PHAR 100
Professor
Hisham Elbatarny
Semester
Fall

Description
Vitamins • substance required for maintenance of normal function but must be provided from external sources • not made in body. • history: vitamins were discovered as a result of studying deficiency disease. ◦ Vit D: Rickets ◦ Vit C: Scurvy ◦ Vit B1: Polyneuritis ◦ Vit B12: Pernicious anemia • classification: has toxicity ifused in excess:will ◦ fat soluble:A, D, E and K accumulate in the body ◦ water soluble: C and B vitamins • drugs ? – When taken as a tablet in pure form are considered drugs – in food no 2 categories where vitamins are used: • vitamins usual use prevention of deficiency states • new area: prevention of non- nutritive diseases → must be based on science Definitions • DRIs: Dietary Recommended intakes ◦ EAR: Estimated average requirement ▪ meets the requirement for 50% of the people in any one category (gender, age etc) ◦ RDA: Recommended dietary allowance ▪ daily intake sufficient to meet the needs of 97 -98% of healthy individuals in a group (age, gender) ◦ AI:Adequate intake ▪ recommended daily intake based on observed or scientific data for specific groups of individuals ◦ UL: highest daily intake that is likely to pose no adverse health risk to almost all individuals • DRIs formulated to keep most individuals healthy ◦ RDA and AI is not intended to treat disease or malnourished individual. Vitamins Supplements are required for: • Inadequate intake ◦ Poverty, and geography ◦ Diet high in one food ◦ Eccentric diet – mentally ill ◦ Idiosyncratic diet ◦ Religious reasons ◦ Alcoholic – poor diet ◦ Restricted diets - vegan diet • Disturbances on absorption ◦ Prolonged diarrhea ◦ Liver disease ◦ GI- diseases: reduce vitamin K and folate absorption ◦ Drugs, e.g. antibiotics • Increased tissue requirements ◦ During growth ◦ Hard work ◦ Pregnancy ◦ Stress ◦ Disease states – hyperthyroidism, fever, tissue wasting Vitamin Therapy Vitamin A and protein:Kwashiorkor • Nutritional approach: diet or a multivitamin to provide adequate amount • Prophylactic approach: amounts to prevent disease • Megavitamin approach ◦ Individuals believe that large doses of vitamins are beneficial in preventing disease ◦ Water soluble – excess excreted usually ◦ Fat soluble accumulate and can cause toxicity ◦ Balance risk and benefit – cost? Vitamin C • required for collagen and intercellular ground substance ◦ required to provide framework for cells – deficiency leads to bleeding and spongy gums in scurvy ◦ prevented by citrus fruits ◦ Limies! : English sailors, used to bring a barrel of limes to prevent scurvy ◦ RDI <100 mg/day • Therapeutic uses ◦ scurvy -- well established ◦ stress conditions – add 100 to 200 mg/day Common Cold • 1970: Linus Pauling presented evidence that vitamin C was effective in the common cold • his view after studying old clinical trials was that there was benefit and recommended high doses, 4 grams per day. • subsequent studies which were well controlled failed to show any benefit except days off work were fewer with the drug. • adverse effects of Vitamin C >1000 mg/day ◦ diarrhea ◦ kidney stones (oxalate) ◦ scurvy if stop suddenly in newborn pregnancy:supplement w/ folate and iron B Vitamins • folate: neural tubes defects, thus supplement women prior to conception and during pregnancy ◦ neural tube defects during embryogenesis can result in spinal bifida • B6: high intake of B6 may lead to a decrease in homocysteine and a lower risk of heart attacks • B12: may not be adequately absorbed in over 60, may need
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