CLASS NOTES: NOV. 11, 2013 NUTRITION CONCEPTSHighlight 11 !Free Radicals and Disease • Free radical • Unstable molecule with one or more unpaired electrons • Look to steal electron from vulnerable compound • Electron-snatching chain reaction • Production: • Normal bodily functions • Oxygen reacts with body compounds & produces free radicals • Environmental factors • Ultraviolet light, air pollution, tobacco smoke !• Antioxidants • Donate an electron —> neutralize free radicals —> end chain reaction • Antioxidants are stable in various forms & therefore do not become free radicals • Free radical attacks •Some are helpful – defense against viruses and bacteria •Most cause damage !• Free radical damage • Contribute to cell damage, disease progression, and aging • Damage polyunsaturated fatty acids in lipoproteins and membranes; disrupts transport of substances into & out of cells • Alter DNA, RNA, and proteins • Creates excesses & deficiencies of specific proteins, impairs cell functions, elicits inflammatory response • Body’s natural defenses and repair systems • Not 100 percent effective • Less effective with age • Oxidative stress: • Can occur when antioxidants are↓or free radicals are↑ • Oxidative stress causative and antioxidants protective in: • Cognitive performance •Cancer, diabetes, hypertension, heart disease •Arthritis and cataracts !Defending Against Free Radicals •System of enzymes against oxidants •Copper, selenium, manganese, and zincCLASS NOTES: NOV. 11, 2013 NUTRITION CONCEPTS• Antioxidant vitamins • Vitamin E • Defends body lipids by stopping free-radical chain • Beta-carotene • Defends lipid membranes • Vitamin C • Protects other tissues, i.e. skin and fluid of blood against free- radical attack !!Antioxidant Roles • Dietary antioxidants defend against cancer and chronic disease • Limit free radical formation • Destroy free radicals or precursors • Stimulate antioxidant enzyme activity (dietary antioxidants, minerals, all work together to make sure that antioxidant enzymes and repair enzymes are working) • Repair oxidative damage • Stimulate repair enzyme activity •Support a healthy immune system !Defending Against Cancer • Cancers due in part by damage to cellular DNA • Antioxidants may protect DNA from this damage • Inverse relationship with vegetable intake • High beta-carotene (one of the key factors, but… no evidence supporting supplementation) • Positive relationship with beef and pork intake - as those go up, risk for cancer also rises • Vitamin C (unique situation) • In high doses —> might act as a pro-oxidant (can be a concern for some nutrients, but not in this situation) —> generate free radicals, possibly useful in destruction of cancer cells; research inconclusive •Vitamin E •May inhibit cancer formation by attacking free radicals that damage DNA; research inconclusive (every time isolate, don’t always get desired results. from food is best benefits) !!!!!!!!!CLASS NOTES: NOV. 11, 2013 NUTRITION CONCEPTS!!!!!!!!!!!!!!!Defending Against Heart Disease •Increased LDL = increased risk for heart disease. but the oxidation for LDL is above the ratio. What’s causing the clogging is the oxidization. •Oxidized LDL scenario • Accelerate formation of artery-clogging plaques • Additional changes in arterial walls • Vitamin C&E protection - Diet high in foods rich in vitamin E reduced atherosclerotic plaques and risk for heart disease - Vitamin C protects against LDL oxidation, increases HDL, and decreases total cholesterol, improves blood pressure; may minimize inflammation and free radical action in arterial wall - Supplements are less clear. Foods give best reduced risks and benefits. Supplement efficacy is less clear - Risk of Vitamin E supplement use by those who already have heart disease is not recommended !!Foods, Supplements, or Both? • Must replenish dietary antioxidants regularly • Foods • Antioxidants and other valuable nutrients • Antioxidant actions of fruits and vegetables are greater than their nutrients alone****** • Supplements • Contents are limited • Physiological levels vs. pharmacological doses (where we see when we have too high of a dose, basically a drug reaction and potential side effects) !CLASS NOTES: NOV. 11, 2013 NUTRITION CONCEPTS!!!Review: Antioxidants • What is a free radical? When do they occur? Molecule that oxidizes others, unstable missing electrons. Can cause oxidative damage. Occur in ultra-violet rays, pollution, tobacco smoke, and everyday daily life. • In excess, antioxidants can act as pro-oxidants. •Antioxidants can protect against disease; examples are the protection the following from free radical damage: DNA, cell membranes
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