The Water Soluble Vitamins: B and C

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