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The Vitamins Chapter 7 Objectives of Chapter Differentiate b/t fat soluble & water soluble vitamins Know primary role (s) of each vitamin Know primary sources for each vitamin o identify your sources Review concerns of deficiency & toxicity for each vitamin *Understand antioxidants Vitamins Essential, non-caloric, organic nutrient needed in small amounts for vital functions in body o small amounts needed is no indication of importance “Precursors or Pro-vitamins” form found in food o once inside body, transformed chemically to “active” form i.e. precursor for vitamin A is beta-caratine vitamin A is only found in animal products, but its precursor beta-carotine is found in vegetables & fruits Vitamins Discovered at beginning of 20th century o still understanding Upon discovery, vitamins proved to reverse diseases in people whose diets were deficient o led people to believe they were “magical” o even today supplement business (multi-billion $$) “the only disease a vitamin can cure is the one caused by a deficiency of that vitamin” Classifications of Vitamins Fat & water soluble (p. 221) o how absorbed, transported, stored, how easily lost Fat soluble (A, D, E, K) o absorbed with fat (require bile), carried by proteins, stored in fat, not easily lost stored in liver & fatty tissue until needed; allows us to NOT need them daily o can become toxic o generally occur in fats & oils of foods Water soluble (B complex & C) o absorbed with water, transported in blood, no sig. storage, easily excreted in urine o < risk of toxicity**, need more regular basis Vitamin A o vision o immune defenses (role in regulation of genes that produce immune system proteins) o normal cell development (promotes cell differentiation) skin, bone & body growth (children) Preformed Vitamin A only in animal products o liver & fish oil best Fruits & Vegetables contain precursor - beta carotine o beta carotine acts as an anti-oxidant o low beta-carotine; may have higher risk of certain cancers, macular degeneration (life long poor diets) o research does NOT show supplementation has same effect as beta-carotene in food Fast foods low levels Avoid supplements exceeding recommendations o Excess vitamins A and D from supplements can easily reach toxic levels (excess beta-carotene will not cause vitamin A toxicity) RDA - 800-1000 RE or 900 micrcrograms 1/2 cup of carrots = 670 micrograms o 1 IU = 0.3 micrograms retinol Vitamin D Body can synthesize from sun o therefore, NOT essential Function: Helps to maintain blood Ca++ levels (bone) o promotes Ca++ absorption from intestines o prevents Ca++ excretion at kidneys *Roles not fully understood (brain, pancreas, skin, reproductive organs) Deficiencies Rickets – weak bones rare in U.S. Osteomalacia – (adult rickets) softening of bones elderly o May also be associated with: High blood pressure, some cancers, type 1 diabetes, heart disease, rheumatoid arthritis, multiple sclerosis Toxicities o most potentially toxic vitamin o Excess vitamins A and D from supplements can easily reach toxic levels (calcification of soft tissue) Vitamin E (“alpha tocopherol”) Functions o anti-oxidant” – serves to defend against “oxidation” o may help to prevent against heart disease Deficiencies - seen with mal-absorption of fat o extremely low fat diets o heavy fat substitutes or “fat blocking agents” use o high heating to oils (fast food) o exercisers may have > need Vitamin K Needed for synthesis of proteins required for blood clotting & bone formation o interferes with function of blood thinners Produced by bacteria in colon (1/2 of what is needed) Deficiencies are rare: infants & those taking long term antibiotics o problems with blood clotting Toxicity – seen with supplementation (infants & pregnancy) o so by prescription only Water Soluble Vitamins B vitamins & Vitamin C Cooking & washing can reduce them in foods b/c water soluble In healthy diet, may be wasting your money to supplement (expensive urine) Physically active have higher needs however, should be made up for by increased energy consumption B Vitamins As a group, involved in breaking down fats, carbohydrates, & proteins to use as fuel o Thiamin (B1), riboflavin (B2), niacin (B3), B6, B12, folic acid, pantothenic acid, & biotin They do NOT contain energy, but are involved in production of energy Deficiencies - exhaustion, depression, impairment of immune system, skin conditions Niacin Functions o energy metabolism Supplements are common b/c it is believed to reduce development of “atherosclerosis” & help with diabetes (termed a “drug”) o lower cholesterol levels Can cause “niacin flush” (dilated capillaries) o improper doses can damage liver & vision Folate (folic acid) Function o required to make new cells Blood cells & digestive cells reproduce most rapidly, anemia & digestive problems are common with deficiency Deficiency seen in this country o associated with birth defects (neural tube - spine problems & mental retardation) 1 in 1000 births o defects occur in 1st few weeks of pregnancy (before most women know) Childbearing age consume 400 ug in addition to normal diet Vitamin B12 Function o helps folate make red blood cells o develop sheath around nerve cells (protect nerves) Deficiency o “pernicious anemia” o nerve damage **only found in animal products o vegetarians & those pregnant are of concern How Are B Vitamins Related to Heart Disease? Homocysteine o amino acid in blood for purpose of building protein o high levels correlate with a severe early form of cardiovascular disease (CVD) May damage blood vessel lining May make blood clot May oxidize LDL’s may be an indicator of CVD risk Deficiencies of folic acid, vitamin B12 or vitamin B6 cause excess homocysteine to build up in the blood Future??? Vitamin C Functions production of collagen (connective tissues) enhances immune response anti-oxidant (high doses however, act as “pro-oxidant”) promotes absorption of iron RDA – 60-100mg (10mg prevents scurvy) o smokers may require closer to 100mg Deficiencies o collagen breakdown, loss of appetite, growth cessation, bleeding gums (scurvy) Vitamin C & Common Cold No study has conclusively proved vitamin can prevent or reduce colds; however, they are some studies suggest this (1000mg/day); be careful of placebo effect Need for Supplementation p. 261 Malnurished - we see clinical signs Subclinical or marginal deficiencies o subtle signs, no outward signs, or masked as non-nutritionally related Always make sure nutrition is proper Supplementation is appropriate in certain situations Women childbearing yrs/Pregnant or Lactating o Folic acid (neural tube defects) Newborns o Vitamin K; formula Lactose intolerant o Calcium Females o Calcium?? Strict vegetarians o B12 Heavy Exercisers o Vitamin E? Smokers o Vitamin E & C Habitual dieters, Elderly, Specific diseases or medications **watch high doses over long term Anti-Oxidants Continued Oxidants are constantly attacking us, so… Defense against free radical damage o anti-oxidant vitamins (vitamin E & C, beta-carotene, & phytochemicals) o scavenge free radicals Vitamin E & beta-carotene defend lipids & LDL’s Vitamin C protects watery components