NUTR 225 Week 7 notes
NUTR 225 Week 7 notes NUTR 225
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This 7 page Class Notes was uploaded by Nbamaka Toure on Saturday February 20, 2016. The Class Notes belongs to NUTR 225 at Oregon State University taught by Josh Jorgensen in Winter 2016. Since its upload, it has received 63 views. For similar materials see General Human Nutrition in Public Health at Oregon State University.
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Date Created: 02/20/16
Chapter 8-Antioxidants • Free Radical: an atom that has lost or gained an electron and is left with an unpaired electron. o Free radicals are highly reactive and can cause damage to molecules in the cell. o Fresh fruits and vegetables are good source of antioxidants o Free radical formation can cause cancer. It can mutate the cell and cause the cell to multiply numerously. • Antioxidants stabilize free radicals and prevent the propagation of free radical generation. • Antioxidants can function in many ways o Some vitamins donate their electrons to free radicals to stabilize them o Some minerals act with complex antioxidant enzyme systems that destroy free radicals Vitamin E • Fat-soluble vitamin • D-alpha-tocopherol is more potent than dl-alpha-tocopherol • Functions of Vitamin E o Primary role is an antioxidant • Sources of Vitamin E o Vegetable oils, nuts, seeds, wheat germ, soybeans o Animal and diary products are poor sources • Vitamin E deficiency may cause increased oxidative stress • Vitamin E is stored in the fat tissue (adipose tissue) Vitamin C • Antioxidant • Required for synthesis of collagen o Most abundant protein in our bodies • Enhances the immune system • Enhances the absorption of iron • What if you don’t consume enough vitamin C? o Scurvy: the most common vitamin C disease § Bleeding gums, loose teeth, weakness (anemia) Beta-carotene • In the class of chemicals called carotenoids • A pro vitamin: inactive precursors that must be converted to active form of a vitamin in the body • A precursor of retinol (the active form of Vitamin A) • You can get Vitamin A in your body by consuming beta -carotene • Spanish, kale, sweet potato, pumpkin, carrots, cantaloupe, broccoli are all good source of beta-carotene Vitamin A • Fat-soluble vitamin o Excess vitamin A is stored in the liver, adipose tissue, kidneys, and lungs • Functions of Vitamin A o Helps for vision o Antioxidant, protecting LDL cholesterol from oxidation 2 o Cell differentiation: the process by which cells mature and specialize (important for healthy epithelial cells & immune function • Vitamin A problems o Vitamin A can be really toxic especially from supplements o Birth defects and permanent damage to the liver and eyes can result o Night blindness is the most common disease of Vitamin A deficiency o Irreversible blindness (xerophthalmia) Selenium • Antioxidant-part of the glutathione peroxidase enzyme system • Production of thyroxine, a thyroid hormone Cancer • Composed of three steps o Initiation: a cell’s DNA is mutated o Promotion: altered cell repeatedly divides o Progression: cells grow out of control go on the other tissues • Factors that increase cancer risk include o Tobacco use o Overweight, obesity o Poor nutrition (diets high in saturated fats, low in fruits & vegetables, excessive alcohol consumption o Physical inactivity- PA known to boost immune system o Infectious agents o Ultraviolet radiation o Environmental exposure 3 • Role of antioxidants in cancer o Preventing oxidation damage to cells o Enhancing the immune system o Inhibiting the growth of cancer cells o Antioxidants (vitamin E and lycopene) reduce damage to blood vessels: § Scavenge free radicals § Reduce low-grade inflammation § Reduce blood coagulation and clot formation 4 Nutrition of Bone Health • Bones help us balance minerals Bone Remodeling • Osteoclasts: cells that erode the surface of bones • Osteoblasts: cells that form new bones Peak bone mass occurs around age 30 Calcium • Necessary for muscle contraction • 99% of body calcium found in bone functions: • forms and maintains bones and teeth • assists with acid-base balance • transmission of nerve impulses • necessary for muscle contraction • blood calcium concentration is tightly controlled to maintain Ca^2+ supply for its intracellular functions Low calcium level: • PTH and vitamin D cause o Kidneys to retain more calcium o Osteoclasts to break down bone and release calcium o Stimulation of calcium absorption from intestines High Calcium Level: • Calcitonin functions to “tone down” calcium o Prevent calcium reabsorption from kidneys o More calcium excreted through urine o Limit calcium absorption from intestines o Inhibit osteoclasts from breaking down bone Bioavailability • The degree rate at which a substance is absorbed into a living system o Different for each micronutrient o Differs between food sources Calcium Bioavailability: • Depends on need and age • Maximum absorbed at one time is limited to 500 mg Calcium supplements: • Maximum absorption is about 500 mg Vitamin D • Fat-soluble vitamin • Can be synthesized by the body by exposure to UV light from the sun • Is a hormone because it is synthesized in one location and acts in another location • Excess is stored in liver and fat tissue Functions: • Required for calcium and phosphorus absorption • Regulates blood calcium levels • Stimulates osteoclasts • Necessary for calcification of bone Vitamin D deficiency: • Osteomalacia o “soft bones” • Increased risk of death from cardiovascular disease • Cognitive impairment in older adults • Severe asthma in children • Cancer Vitamin K 2 Functions: • blood coagulation (prothrombin synthesis) • bone metabolism (osteocalcin) o osteocalcin puts mineral in bone Sources of Vitamin K: • green leafy vegetables, vegetables oils • infants get vitamin K injection within an hour of birth What if you consume too much vitamin K? - no side effects from large quantities What if you don’t consume enough vitamin K? - reduced blood clotting, excessive bleeding - occurs with diseases that limit absorption of fat in the small intestine 3
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