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The Water Soluble Vitamins: B and C Chapter 10 Nalini Narahari Overview of Vitamins Vitamins are organic substances required in minute quantities (micrograms to milligrams) Vita means life; amine: nitrogen containing The first vitamins discovered has nitrogen Specific functions include: Nurture growth; reproduction; maintain life Prevent deficiency diseases Do not provide energy; Help the enzymes that release energy from the carbs, fats and proteins Cont • Structure: • • Food contents: • • • Individual units; not connected like molecules of glucose, fatty acids and amino acids Vitamins present in foods are ingested Required in small quantities; measured in micro grams and milligrams Know the terms: • Bioavailability; precursors; coenzymes Thiamin Water soluble vitamin Part of the coenzyme, Thiamin Pyro Phosphate (TPP) Assists in energy metabolism Recommendations: Men 1.2 mg/d; Prolonged The 1998 RDA women 1.1 mg/d deficiency leads to beriberi custom of polishing rice in Asia Cont Severe thiamin deficiency in alcohol abusers: Wernicke- Korsakoff syndrome Disorientation Loss of short term memory Jerky eye movements Staggering gait Food sources: Whole grain, fortified and enriched products Pork; ham Riboflavin Acts as coenzyme in many metabolic reactions Flavin Mono Nucleotide (FMN) Stable when heated Breaks down in light and radiation Milk sold in opaque/translucent containers Recommendations: Men 1.3 mg/d 1998 RDA women 1.1 mg/d Cont Deficiency: Ariboflavinosis Inflammation GI tract Food of the mouth, skin ,eyes, and sources: Milk and milk products Enriched products Liver Canned clams Niacin Occurs as nicotinic acid and nicotinamide Body transforms nicotinic acid to nicotinamide, a major form of niacin in the blood Body can make niacin from its precursor, tryptophane Stable in heat Recommendations: 1998 RDA Men 16 mg/d Women 14 mg/d Niacin:lipid lowering function (niacin flush) Cont Severe deficiency leads to pellagra Dermatitis Diarrhea Dementia Food sources: Milk; eggs, meat, poultry, fish, Whole grains and enriched products All protein containing foods Biotin As a coenzyme plays a major role in metabolism Delivers a carbon to 3-carbon pyruvate: formation of oxaloacetate to continue with the TCA cycle Stable to heat 1998 Adequate intake (AI) Adults 30 micrograms/d 10 Vitamin B12 Cobalamin Close relationship between vitamin B12 and folate Depend on each other for activation Microwave cooking destroys B12 Intrinsic factor: The HCL and pepsin in the stomach release B12 from the protein foods to which it is attached 20 Cont The next step the intrinsic factor attaches to B12 Then the whole complex passes to the small intestine where the gradual absorption of B12 occurs Reabsorption of B12 happens continuously Recommendations: 1998 RDA Adults 2.4micrograms 21 Cont Deficiency caused by inadequate absorption rather than poor intake Lack of HCL or lack of intrinsic factor Without HCL, the vitamin cannot be released from protein, and cannot attach to intrinsic factor Atrophic gastritis: Commonly in older people, the stomach cells get damaged Could be due to iron deficiency or Helicobacter pylori No healthy cells; No action of HCL and intrinsic factor 22 Cont Result is pernicious anemia due to a combination of atrophic gastritis and lack of intrinsic factor Other factors are defective gene for intrinsic factor, or if the stomach is injured or damaged In that case B12 must be injected Nasal spray of B12; absorption is rapid High dose of folate masks B12 deficiency In both deficiency states, the first symptom is that the blood cells grow rapidly Either of the vitamins-supplement will be effective 23 Cont However if folate is administered when B12 is needed, the situation will be disastrous Results in devastating neurological symptoms B12 deficiency leads to nerve damage caused by destruction of myelin sheaths that protect the nerves Note: folate can clear the blood symptoms but cannot stop the nerve damage Food sources: Animal sources: meat, fish, poultry, eggs, shellfish, milk/products, fortified cereals; soy milk with B 12 24 Non- B Vitamins Choline: Body can synthesize; needed for the synthesis of acetyl choline, a neurotransmitter, and Phospholipid lecithin Deficiency may cause liver damage 1998 AI men 550 mg/d; women 425 mg/d Food sources; Milk, liver,eggs and peanuts 25 Cont Inositol and carnitine: Nonessential nutrients synthesized in the body from glucose and amino acids respectively Inositol used in cell membranes No recommendations for either Vitamin imposters: caution! PABA; bioflavinoids, quinone, coenzyme Q10, B5, B15 etc 26 Vitamin C: Ascorbic Acid Vitamin C was isolated in 1930s James Lind, a British physician did the first nutrition experiment on 12 sailors The pair who received the citrus fruits recovered from scurvy Functions Acts include: as an antioxidant Protects lipids in the blood and cell membranes from oxidative damage 27 Cont Assists in collagen formation as a cofactor Helps in the hydroxylation of carnitine Conversion of tryptophane to neurotransmitters serotonin and norepinephrine Cure for common cold and stress relief: Collagen is the main structural protein in bones, teeth and connective tissues Research is still inconclusive Vitamin C enhances iron absorption and regulates the absorption of copper 28 Cont Recommendations: 2000 RDA Men 90 mg/d women 75 mg/d Smokers =35 mg/d Deficiency leads to scurvy Bleeding gums; pinpoint hemorrhage Fatigue; microcytic anemia Loss of appetite Slow wound healing; frequent infections Scaly and dry skin; neurological symptoms 29 Cont Toxicity: Nausea, abdominal cramps and diarrhea Interference with medical diagnostic tests False positive or false negative to detect diabetes Individuals taking anticlotting medication may counteract the effect if they take high doses of Vitamin C Also people with kidney disease Dangerous for people with iron overload 30 Cont Rebound scurvy: When mega doses of Vitamin C are taken, body excretes it rapidly When abruptly stopped, the body is unable to stop excreting immediately Result is a state of Vitamin C deficiency Even though few studies to support the theory, the Supplements need to be tapered off 31 Cont Food sources: Citrus fruits, cabbage type of vegetables, green leafy vegetables, cantaloupe, strawberries, lettuce, tomatoes, potatoes, papaya and mango Protect foods rich in vitamin C Store in airtight wrappers Close the lids tight Do not over cook the vegetables and not waste water after cooking 32 The Water Soluble Vitamins 33 Highlight Section Vitamin and mineral supplements Correct overt deficiencies Improve nutrition status Reduce disease risks Support increased needs Improve body’s defenses Toxicity issues; misleading claims; cost Regulation of supplements 34
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