The Water-Soluble Vitamins: B Vitamins and Vitamin C Chapter 10 - Part 2 !Vitamin C • Similar to B vitamins: • Water soluble • Serves as a cofactor for an enzyme •Differs from B vitamins •Acts as an antioxidant •Loses electrons easily !Free Radicals • Free radical • Has one or more unpaired electrons • Makes it unstable and highly reactive • Can damage other molecules •Oxidative Stress – production of oxidants and free radicals exceed the body’s ability to handle them and prevent damage !Vitamin C- Roles •Antioxidant (Acts as this) because of its ability to lose electrons easily, it can… • Defends against free radicals • Loses electrons easily • Protects tissues from oxidative stress • Disease prevention •Enhances iron absorption (because of its role as an antioxidant) !• Cofactor in collagen formation - requires iron and the Vitamin C is protecting from oxidation. Acting as cofactor as antioxidant. • Matrix for bone and tooth formation • Requires iron • Requires Vitamin C to protect iron from oxidation • Cofactor in other reactions • Transport of fatty acids • Conversion of amino acids to neurotransmitters • Making of hormones • In stress- under stress, releases Vitamin C • Adrenal glands release vitamin C& hormones into blood• Types of stress that increase vitamin C • Infections, burns • Extremely high or low temperatures • Intakes of toxic heavy metals • Lead, mercury, cadmium • Chronic use of certain medications • Aspirin, oral contraceptives • Cigarette smoking (BIGGEST) - because of all the free radicals that are formed !•Prevention and treatment of common cold •Conflicting and controversial research • Some studies show modest benefits: fewer colds, fewer days, shorter duration • About 8% reduction in duration with 200 mg • Deactivates histamine (like an antihistamine) !• Vitamin C recommendations • Prevent overt symptoms of scurvy • Absorption maximum • 200 mg • Higher vitamin C levels for smokers !• Notable signs of deficiency (symptoms of scurvy) • Gums bleed easily around teeth • Capillaries under skin break spontaneously !!Vitamin C- Deficiency •Scurvy – more than a month of inadequate intake •Inadequate collagen synthesis—> hemorrhaging (not healing b/c not enough collagen) • Muscles degenerate, anemia, infection • Skin becomes rough, brown, scaly, dry • Wounds do not heal(no scar tissue) • Bone rebuilding ceases —> ends become soft,fractures • Teeth become loose • Psychological signs:hysteria,depression • Death !Vitamin C - Toxicity •Supplementation side effects •Diarrhea • GI distress• UL–2000mg (daily) • Interference with medical regimens • Medical conditions in which high doses of vitamin C should not be consumed !Vitamin C - Food Sources • Fruits and vegetables • Citrus, peppers, broccoli and other dark green veggies, etc. • Potatoes – not highest source, but very common (highest source in American diet- eat a lot of them) (Also anywhere where potatoes are a staple) •Vulnerable to heat and oxygen - prepare foods in a variety of ways. Reducing cooking times or not cooking would be better to keep •Raw fruits provide more •Used as antioxidant by food manufacturers •“Ascorbic acid” is a fancy name for Vitamin C !Review of Vitamin C • Describe free radicals: molecules that are short electrons, so trying to grab electrons from any source they can get. They cause oxidation in body, damage in a body. Domino effect (grab onto something and turn something into a free radical, then that free radical goes to grab something else, etc. - This is what this oxidation does. Cancer because of this) • Vitamin C acts as an antioxidant and a cofactor in other reactions. • List food sources high in vit C: citrus, peppers, and dark, leafy, vegetables • Modest, but common source of vit C: potatoes !!Highlight 10 - Vitamin and Mineral Supplements !Consumer motives Dietary insurance Health insurance Costly- all these are not free. Question is whether or not you are getting any effect out of the supplement Financially and physically costly Self prescribed is dangerous. If taking, let your physician know Improving food choices is the preferred course of action if trying to get a better intake of vitamins and minerals !Arguments for Supplements Good when correcting overt deficiencies Therapeutic doses when a specific deficiency Acting as a drug (in pregnant woman, folic acid, iron, etc.) Support increased nutrient needs Certain stages of life Childbearing years: iron, folatePregnancy Infancy: Vitamin K given in injection in foot for infancy Depending on method of feeding. If formula, don’t need supplements. Breastfeeding, need to make sure that they use the recommended supplements !Supplements can improve nutrition status low kcal intake- if can not meet nutrient needs, supplement would be recommended Elderly- because low kcal intake, but also lower absorption Those who eliminate food groups - vegetarians, don’t eat dairy, etc. Improve body defenses Probiotics when taking antibiotics to reestablish gut flora Don’t have clear definitive if vitamin and mineral supplements can reduce disease risk !Who needs Supplements? Specific nutrient deficiencies Low energy intakes Vegans and older adults Lactose intolerance Certain medications Certain stage os life ccle Inadequate milk intake, sun exposure, or dark skin Medical conditions !Who should NOT take supplements? Men and postmenopausal women should not take excess iron (high iron is harmful and deficiency is not likely) - heart disease and heart attacks as a result Exercise increases iron needs Smokers should not take beta-carotene (high lung cancer risk and mortality. Acts as pro-oxidant) Postmenopausal women should not take Vitamin A (reduces bone density) Surgery patients should not take Vitamin E the week before a surgery b/c blood thing Why are examples like this important? - Don’t self prescribe, drug company wouldn’t be a good resource- best interest is your money, not your health, resources: physicians, dietitians, clinical controlled trials. Comprehensive literature review, not person just hired at GMC or Vitamin Shoppe - don’t have nutrition background !Arguments Against
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