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Define free radicals.
How they are produced and the long term consequences of excess free radical production?
- When an atom loses an electron during oxidation. Unpaired e- in the outermost shell are highly unstable and are called free radicals.
- Free radicals are formed during metabolic processes when we inhale oxygen, exposure to pollution, excess sunlight, toxic substances, radiation, smoke, and asbestos.
- Long term: increases individual's risk for chronic diseases and uncontrollable free radical formation.
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Which vitamins and minerals are antioxidants or part of antioxidant systems?
- Vitamins A, C, E
- Beta-Carotene
- Selenium
- Cu, Fe, Zn, Mn part of the superoxide dismutase enzyme complex.
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Antioxidant Vitamins
Antioxidant Vitamins work by donating their electrons or H molecules to free radicals to stabilize them and reduce the damage by oxidation.
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Antioxidant Minerals and phytochemicals
- -Minerals convert free radicals to less damaging substances that are excreted by the body.
- -Also break down fatty acids that have become oxidized. This destroys the free rads ass. with them.
- -Antioxidant enzyme systems like superoxide dismutase converts free rads to less damaging substances, like H2O2.
- Phytochemicals and beta-carotene help stabilize free radicals and prevent damage to cells and tissues.
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What vitamin is needed to regenerate vitamin E? What mineral
spares vitamin E?
- Vitamin C regenerates Vit E.
- Selenium spares Vit E indirectly from oxidation.
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What population(s) require more vitamin C AND why?
Low socioeconomic status, low intake, pregnant women, alcohol and drug abusers, smokers, infants fed cow's milk, elders
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List the antioxidant enzyme systems and their cofactors
discussed in lecture. Describe how these systems help fight oxidative damage.
- -Superoxide dismutase converts free radicals to less damaging substances like hydrogen peroxide.
- Cofactors: Cu, Zn, and Mn
- -Catalase removes hydrogen peroxide from the body by converting it to water and hydrogen.
- Cofactors: Iron
- -Glutathione peroxidase removes hydro pero from the body and stops the production of free radicals in lipids.
- Cofactors: Selenium
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Describe briefly how vitamin A works to ensure healthy vision (i.e., the visual cycle).
- -It enables us to react to changes in the brightness of light
- -It enables us to distinguish between different wavelengths, or see different colors.
- -When Vit A is deficient, people suffer from night blindness
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Describe the relationship between antioxidant nutrients and
the risk for cancer and cardiovascular disease. How can antioxidants decrease
the risk for both diseases? Are antioxidant supplements beneficial in either
primary or secondary prevention?
- Antioxidants are substances that may protect cells from the damage caused
- by free radicals. Free radical damage may lead
- to cancer. Antioxidants interact with and stabilize free radicals and may
- prevent some of the damage free radicals might otherwise cause.
- antioxidants may slow or possibly prevent the development
- of cancer. However, information from recent clinical trials is less clear.
- In recent years, large-scale, randomized clinical trials reached inconsistent
- conclusions.
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Describe the antioxidant conundrum as it relates to cancer therapy.
What are some of the difficulties comparing studies
examining antioxidants and cancer? Would you recommend antioxidant supplements
to a cancer patient? Why or why not? Support your answer using the information
in the additional reading.
- Radiation therapy is creating free radicals. Cancer therapy kills your cells but you need antioxidants to repair them.
- Difficulties-there was problems comparing results. The results were different.
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Define phytochemicals and describe their relationship with
the risk for cancer, specifically those discussed in class (beta-carotene and
lycopene). What foods are high in these phytochemicals?
- Phytochemicals: chemicals found in plants that reduce our risk for diseases like cancer and heart disease.Found in whole grains, fruits, vegetables, legumes, nuts, garlic and soy products.
- Beta-carotene:
a provitamin of Vit. A. - Fruits and Vegetables that are red, orange, yellow and deep green are high in B carotene. tomatoes, carrots, cantaloupe, sweet potatoes, etc.
- Lycopene:
found in tomatoes
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Which vitamins and minerals are involved in bone development and/or formation?
Calcium, Vit D, Fluoride, Vit A, Vit K, Phosphorus, and Magnesium
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Describe the composition of bone.
- About 65% of bone tissue is made up of minerals (Ca and P) that provide hardness; 35% is a mix of organic substances that provide strength, durability and flexibility.
- Collegen.
- Cortical bone is compact and very dense, 80% of skeleton is cortical.
- Trabecular bone is the ends of long bones, inside the spine and pelvis. 20%. spongy bone.
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What are the differences between cortical bone and
trabecular bone? Which is most susceptible to osteoporosis?
- Cortical bone is compact and very dense, 80% of skeleton is cortical.
- Trabecular bone is the ends of long bones, inside the spine and pelvis. 20%. spongy bone.
- This has high turnover and so more susceptible to osteoporosis.
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Discuss the processes of bone growth, modeling, and
remodeling. Include the role of osteoclasts and osteoblasts in bone resorption
and formation.
- Bone Growth-The size of bone increases. Growth begins in womb, cont until early adulthood.Bone Modeling-determines bone shape, in early adulthood.
- Bone Remodeling-
recycling bone tissue through breaking down existing bone (resorption thru osteoclasts) and forming new bone (formation through osteoblasts).
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How is bone density measured?
DXA
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