NUTR 250 Lecture 20: NUTR 250 Lecture 20 (4/13/17)

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Nutrition & Health Sciences
NUTR 250

NUTR 250 Lecture 20 (4/13/17) Risk of Vitamin B-12 Deficiency ● Vegetarians and vegans ● Infants with vegetarian or vegan mothers ● Elderly ● Malabsorption syndrome ○ Require monthly injections, nasal gel, very high oral doses Vitamin C ● Ascorbic acid Vitamin C Function ● Electron donor ● Antioxidant defense ○ Donates electron to free radicals ● Synthesis of collagen, tyrosine, thyroxine, neurotransmitters, and bile acids Vitamin C Sources ● Citrus fruits ● Peppers ● Green vegetables ● Unstable during storage, processing, and cooking Vitamin C RDA and UL ● RDA: ○ Men: 90 mg/day ○ Women: 75 mg/day ○ Smokers require an extra 35 mg/day ● DV: 60 mg/day ● UL: 2 g/day ○ Kidney stones, bloating, diarrhea Vitamin C Absorption, Transport, Storage, and Excretion ● Absorbed in small intestine by active transport or facilitated diffusion ● Stored in pituitary glands, adrenal glands, white blood cells, eyes, and brain Vitamin C Deficiency ● Scurvy ○ Fatigue, pinpoint hemorrhages, bleeding gums, bleeding joints, impaired wound healing, bone pain, fractures, diarrhea, depression ○ Fatal if untreated Vitamin C Preventive Effects ● Good vitamin C status reduces the risk of GI and lung cancer and heart disease ● supplementation>100 ,g/day may reduce cold duration Choline Sources ● Free choline in food ● Phosphatidylcholine (lecithin) ● Foods of animal origin ● Grains ● Nuts ● Vegetables ● Fruits Choline AI and UL ● AI: ○ Mrn: 550 mg/day ○ Women: 425 mg/day ● UL: 3.5 g/day ○ Fishy body odor, low blood pressure, sweating, vomiting, salivation, GI effects Choline Metabolism and Function ● Absorbed in small intestine by transport proteins ● All tissues store it ● Excreted in urine Choline Functions ● Phospholipids ● Precursor for acetylcholine ○ acetyl-CoA ● Export of VLDL from liver Choline Deficiency ● Extremely rare ● Liver and muscle damage Vitamin-Like Compounds ● Necessary for normal metabolism ● Increased requirements during growth ● Not essential because we can produce them on our own ● No deficiencies because we can produce them on our own ○ Unless there is a birth defect or hereditary problem ● No DRI ● Carnitine ○ Animal foods, biosynthesis, fatty acid transport into mitochondria ● Taurine ○ Animal foods, energy drinks, biosynthesis, involved in vital functions in the body Water ● Balance is essential ● Humans have no water reserves Water in Human Body ● 55% of body weight ○ ⅓ is extracellular ■ Intravascular fluid and interstitial fluid ● 11 liters interstitial ● 4 liters intravascular ○ ⅔ is intracellular Solutes ● Intracellular fluid ○ Cations: potassium and magnesium ○ Anions: phosphate and sulfate ● Extracellular fluid ○ Cations: sodium and calcium ○ Anions: chloride and bicarbonate Fluid Balance ● Water is controlled by electrolyte concentrations ○ Transmembrane pumps ○ Electrolytes aren’t very soluble Osmosis ● Movement of water across a semipermeable membrane ○ From low electrolyte concentration to high electrolyte concentration ○ Equilibrium ● Water can’t just go through membranes Functions of Water ● Transport nutrients and oxygen ● Body fluids ○ Saliva, bile, amniotic fluid ● Lubricant ● Solvent ● Participates in reactions ○ Hydrolysis ● Removal of waste products ○ Urine ● Temperature regulation ○ Sweat
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