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Water-Soluble Vitamins - PowerPoint PPT Presentation

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Water-Soluble Vitamins. Water soluble Readily excreted – expensive urine Can be lost from food by cooking/storage Typically work as part of enzymes in metabolism Relatively high absorption rate Severe deficiencies rare Vitamins – Niacin, Thiamine, Folic Acid, Riboflavin, B12, and C.

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water soluble vitamins
Water-Soluble Vitamins
  • Water soluble
  • Readily excreted – expensive urine
  • Can be lost from food by cooking/storage
  • Typically work as part of enzymes in metabolism
  • Relatively high absorption rate
  • Severe deficiencies rare
  • Vitamins – Niacin, Thiamine, Folic Acid, Riboflavin, B12, and C.
enrichment act of 1941 and 1998
Enrichment Act of 1941 and 1998
  • Milling of rice, wheat, oats, etc…
  • significantly reduces nutritional quality
  • Whole grains contain original nutrients
  • Enrich with
  • thiamin, riboflavin, niacin, folate, iron
  • Enriched grains still
  • deficient in B-6, magnesium and zinc
  • Destroyed by alkaline and heat
  • Coenzyme: Thiamin pyrophosphate (TPP)
  • Absorbed in the jejunum by a carrier-mediated system
  • Transported by RBC in the blood
  • Deficiency
  • Beriberi
    • Weakness, nerve degeneration, irritability, poor arm/leg coordination, loss of nerve transmission
    • Edema, enlarge heart, heart failure
food sources of thiamin
Food Sources of Thiamin
  • Wide variety of food
  • White bread, pork, hot dogs, luncheon meat, cold cereal
  • Enriched grains/ whole grains
  • Thiaminase found in raw fish
  • 1.1 mg/day for women
  • 1.2 mg/day for men
  • Most exceed RDA in diet
  • Surplus is rapidly lost in urine; non toxic
  • Coenzymes:
    • Flavin mononucleotide (FMN)
    • Flavin adenine dinucleotide (FAD)
  • Oxidation-reduction reactions
  • Electron transport chain
  • Citric Acid Cycle
  • Catabolism of fatty acids
absorption transport metabolism of riboflavin
Absorption, Transport, & Metabolism of Riboflavin
  • HCL in the stomach release riboflavin from its bound forms
  • Absorption
    • Active or facilitated transport during low to moderate intake
    • Passive absorption during high intake
    • Increase with intake
  • Transported by a protein carrier in the blood
functions of riboflavin
Functions of Riboflavin
  • Accepts electrons
  • Electron Transport Chain
  • Succinate Fumarate
  • Citric Acid Cycle
  • Participates in beta oxidation
  • FMN shuttles hydrogen ions and electrons to into the electron transport chain
  • Metabolism of oxidized glutathione
deficiency of riboflavin
Deficiency of Riboflavin
  • Ariboflavinosis
    • Glossitis, cheilosis, seborrheic dermatitis, stomatitis, eye disorder, throat disorder, nervous system disorder
  • Occurs within 2 months
  • Usually in combination with other deficiencies
who is at risk for deficiency
Who is at Risk For Deficiency?
  • Rare
  • Low milk/dairy intake
  • Alcoholics
  • Long term phenobarbital use
food sources of riboflavin
Food Sources of Riboflavin
  • Milk/products
  • Enriched grains
  • Liver
  • Oyster
  • Brewer’s yeast
  • Sensitive to uv radiation (sunlight)
  • Stored in paper, opaque plastic containers
rda for riboflavin
RDA for Riboflavin
  • 1.1 mg/day for women
  • 1.3 mg/day for men
  • Average intake is above RDA
  • Toxicity not documented
  • Nicotinic acid (niacin) & nicotinamide (niacinamide)
  • Coenzyme
    • Nicotinamide adenine dinucleotide (NAD)
    • Nicotinamide adenine dinucleotide phosphate (NADP)
  • Oxidation-reduction reaction
  • Metabolic reactions
absorption transport and storage of niacin
Absorption, Transport and Storage of Niacin
  • Readily absorbed from the stomach and small intestine
  • Absorption: active transport and passive diffusion
  • Transported from the liver to all of the tissues where it is converted to the coenzymes
deficiency of niacin
Deficiency of Niacin
  • Pellagra
    • 3 Ds
    • Occurs in 50-60 days
    • Decrease appetite & weight
  • Prevented with an adequate protein diet
  • Enrichment Act of 1941
  • Only dietary deficiency disease to reach epidemic proportions in the U.S.
  • Who is at risk?
    • (Untreated) corn as main staple, poor diet, Hartnup disease, alcoholics
food sources of niacin

Enriched grains

Beef, chicken, turkey, fish

Heat stable; little cooking loss

60mg tryptophan can be converted into 1 mg niacin

Food Sources of Niacin
rda for niacin
RDA for Niacin
  • 14 NE/day for women
  • 16 NE/day for men
niacin as a medicine
Niacin as a Medicine
  • 75-100 x RDA can lower LDL and TG and increase HDL
  • Slow/ reverse progression of atheroscelerosis with diet and exercise
  • Toxicity effects
    • Flushing of skin, itching, nausea, liver damage
  • Free and bound form
  • Biocytin (protein bound form)
  • Biotinidase in small intestine
  • Metabolism of CHO, fat, protein (C skeleton)
  • DNA synthesis
functions of biotin
Functions of Biotin
  • Assists in the addition of CO2 to substances
  • Carboxylation of acetyl-CoA to form malonyl-CoA for the elongation of a fatty acid chain
  • Addition of CO2 to pyruvate to yield oxaloacetate
  • Breaks down leucine
  • Allows 3 essential amino acids to be oxidized for energy
food sources of biotin
Food Sources of Biotin
  • Cauliflower, yolk, liver, peanuts, cheese
  • Intestinal synthesis of biotin
  • Biotin content only available for a small number of foods
  • Unsure as to bioavailablity of synthesized biotin
  • We excrete more than we consume
  • Avidin inhibits absorption
    • > a dozen of raw eggs a day to cause this effect
biotin needs
Biotin Needs
  • Adequate Intake is 30 ug/day for adults
  • This may overestimate the amount needed for adults
  • No Upper Limit for biotin
who is at risk for deficiency25
Who is at Risk For Deficiency?
  • Rare
  • High intake of raw egg white diet
  • Alcoholics
  • Biotinidase deficiency
  • Anticonvulsant drug use
  • Signs & symptoms: skin rash, hair loss, convulsion, neurological disorders, impaired growth in children
vitamin b 6 pyridoxal pyridoxine pyridoxamine
Vitamin B-6: Pyridoxal, Pyridoxine, Pyridoxamine
  • Main coenzyme form: pyridoxal phosphate (PLP)
  • Activate enzymes needed for metabolism of CHO, fat , protein
  • Transamination
  • Synthesis of hemoglobin and oxygen binding and white blood cells
  • Synthesis of neurotransmitters
deficiency of vitamin b 6
Deficiency of Vitamin B-6
  • Microcytic hypochromic anemia
  • Seborrheic dermatitis
  • Convulsion, depression, confusion
  • Reduce immune response
  • Peripheral nerve damage
  • Who is at risk?
    • Elderly
    • Alcoholics
      • Alcohol decreases absorption
      • Destroy the coenzyme form
food sources of vitamin b 6
Food Sources of Vitamin B-6
  • Meat, fish, poultry
  • Whole grains (not enriched back)
  • Banana
  • Spinach
  • Avocado
  • Potato
  • Heat and alkaline sensitive
rda for vitamin b 6
RDA for Vitamin B-6
  • 1.3 mg/day for adults
  • 1.7 mg/day for men over 50
  • 1.5 mg/day for women over 50
  • Daily Value set at 2 mg
  • Average intake is more than the RDA
factors that affect b 6 requirement
Factors That Affect B-6 Requirement
  • L-DOPA-medication used to treat Parkinson’s disease and
  • Isoniazid-antituberculosis medication
  • Reduce blood concentration of PLP
  • Need extra vitamin B-6
  • Preeclampsia
  • Reduce blood concentration of PLP
  • Will supplementation will reduce preeclampsia?
b 6 as a medicine
B-6 As A Medicine?
  • PMS
    • B-6 to increase the level of serotonin
    • Improve depression
    • Not a reliable treatment
  • Carpal tunnel syndrome
  • Toxicity potential
  • Can lead to irreversible nerve damage with > 200 mg/day
folate folic acid folacin
Folate (Folic acid, Folacin)
  • Consists of pteridine group, para-aminobenzoic acid (PABA), and glutamic acid
  • Coenzyme form: tetrahydorfolic acid (THFA)
functions of folate
Functions of Folate
  • DNA synthesis
    • Transfer of single carbon units
    • Synthesis of adenine and guanine
    • Anticancer drug methotrexate
  • Homocysteine metabolism
  • Neurotransmitter formation
deficiency of folate
Deficiency of Folate
  • Similar signs and symptoms of vitamin B-12 deficiency
  • Pregnant women
  • Alcoholics
    • Interferes with the enterohepatic circulation of bile/folate
neural tube defects

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Neural Tube Defects
  • Spina bifida
  • Anencephaly
  • Importance of folate before and during pregnancy

(Fig. 10-8)

food sources of folate
Food Sources of Folate
  • Liver
  • Fortified breakfast cereals
  • Grains, legumes
  • Foliage vegetables
  • Susceptible to heat, oxidation, ultraviolet light
rda for folate
RDA for Folate
  • 400 ug/day for adults
  • Daily Value is set at 400 ug
vitamin b 12
Vitamin B-12
  • Cyanocobalamin. methlcobalamin,
  • 5-deoxyadenosylcobalamin
  • Contains cobalt
  • Folate metabolism
  • Maintenance of the myelin sheaths
  • Rearrange 3-carbon chain fatty acids so can enter the Citric Acid Cycle
functions of vitamin b 12
Functions of Vitamin B-12
  • Helps convert methylmalonyl CoA to succinyl CoA (citric acid cycle)
  • RBC formation
  • Nerve functions
    • Maintains myelin sheath
  • Megalobalstic anemia
deficiency of vitamin b 12
Deficiency of Vitamin B-12
  • Pernicious anemia
    • Never degeneration, weakness
    • Tingling/numbness in the extremities (parasthesia)
    • Paralysis and death
    • Looks like folate deficiency
  • Usually due to decreased absorption ability
  • Achlorhydria especially in elderly
  • Injection of B-12 needed
  • Takes ~20 years on a deficient diet to see nerve destruction
who is at risk for deficiency42
Who is at Risk For Deficiency?
  • Vegans
  • Breastfed infants of vegan moms
  • Elderly
  • Individuals with AIDS or HIV
food sources of vitamin b 12
Synthesized by bacteria, fungi and algae

(Stored primarily in the liver)

Animal products

Organ meat



Hot dogs


Food Sources of Vitamin B-12
rda for vitamin b 12
RDA for Vitamin B-12
  • 2.4 ug/ day for adults and elderly adults
  • Average intake exceeds RDA
  • B-12 stored in the liver
  • Non-toxic
vitamin c
Vitamin C
  • Ascorbic acid (reduced form), dehydroascorbic acid (oxidized form)
  • Synthesized by most animals (not by human)
  • Absorbed by a specific energy dependant transport system
  • Passive transport if intake is high
  • Decrease absorption with high intakes
  • Excess excreted
functions of vitamin c
Functions of Vitamin C
  • Reducing agent (antioxidant)
  • Iron absorption
  • Synthesis of carnitine, tryptophan to serotonin, thyroxine, cortiscosteroids, aldosterone, cholesterol to bile acids
  • Immune functions
  • Cancer prevention?
  • Collagen synthesis
  • Can donate and accept hydrogen atoms readily
  • Water-soluble intracellular and extracellular antioxidant
  • Must be constantly enzymatically regenerated
  • Needs are higher for smokers
deficiency of vitamin c

Deficient for 20-40 days

Fatigue, pinpoint hemorrhages

Bleeding gums and joints. Hemorrhages

Associated with poverty

Rebound scurvy

immediate halt to excess vitamin C supplements

Who is at risk?

Infants, elderly men

Alcoholics, smokers

Deficiency of Vitamin C
food sources of vitamin c
Citrus fruits


Green peppers




Romaine lettuce


Easily lost through cooking

Sensitive to heat

Sensitive to iron, copper, oxygen

Food Sources of Vitamin C
rda for vitamin c
RDA for Vitamin C
  • 90 mg/day for male adults
  • 75 mg/day for female adults
  • +35 mg/day for smokers
  • Average intake ~72 mg/day
  • Fairly nontoxic (at <1 gm)
  • Upper Level is 2 g/day
  • Warning to people with hemochromatosis, oxalate kidney stones