Vitamin C

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Transcript Vitamin C

NS 315
Unit 7: Water Soluble Vitamins
Jeanette Andrade MS,RD,LDN,CDE
Kaplan University
Objectives
• What are we going to
learn about tonight?
–
–
–
–
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Vitamin C
Vitamin B1
Riboflavin
Niacin
Pantothenic Acid
–
–
–
–
Biotin
Folate
Vitamin B12
Vitamin B6
Vitamin C
• Also known as ascorbic acid
• We have to obtain vitamin C through the
diet
• RDAs:
– Males 19-70 years old 90 mg/day
– Females 19-70 years old 75 mg/day
– Smokers males 19+ 125 mg/day
– Smokers females 19+ 110 mg/day
• What foods contain Vitamin C?
Functions of Vitamin C
• Required for the synthesis of collagen
• Required for the synthesis of
neurotransmitter; norepinephrine
• Required for synthesis of carnitine (fat
oxidation)
• Effective antioxidant
Deficiency of Vitamin C
• The more severe deficiency- scurvy occurs
with lack of vitamin C in the diet
• Scurvy:
– Rare in United States, but can occur in
malnourished and alcoholics
– Bruising, bleeding gums and dental problems,
anemia and dry hair
http://www.merck.com/mmhe/sec12/ch154/ch154i.html
Toxicity of Vitamin C
• Up to 2 gm of vitamin C per day causes no
adverse effects
• Most common problems are abdominal
pain and osmotic diarrhea (due to
unabsorbed vitamin C)
• At risk populations: Renal disease
patients, hemochromatosis, thalassemia
and sideroblastic anemia patients
Vitamin B1
• Also known as Thiamin or Aneurine
• Phosphorylated forms: Thiamin
monophosphate (TMP), Thiamin
triphosphate (TTP), and Thiamin
pyrophosphate (TPP)
• RDAs for Thiamin:
– Males 19-70 years old 1.2 mg/day
– Females 19-70 years old 1.1 mg/day
• What foods contain Thiamin?
Functions of Thiamin
• Coenzyme function as TPP
• Assists in pyruvate dehydrogenase,
alpha-ketoglutarate dehydrogenase, and
branched-chain ketoacid dehydrogenase
• Coenzyme needed in Pentose Phosphate
Pathway, an alternate for glucose oxidation
Thiamin
Some Thiamin Containing
Enzymes
http://pubs.niaaa.nih.gov/publications/arh27-2/IMAGES/Page138.gif
Deficiency of Thiamin
• Primary deficiency: people consuming white
rice or highly refined carbohydrates in
developing countries (Beriberi) and alcoholics
(Wernicke- Korsakoff Syndrome)
• Secondary deficiency: Increased demand,
impaired absorption, impaired metabolism
• 3 common Beriberis:
– Dry
– Wet
– Infantile
http://www.merck.com/mmpe/sec01/ch004/ch004f.html
Beriberi
• Dry:
– Peripheral neurologic deficits
– Effect mainly lower extremities and
with continued deficiency will effect
the arms
• Wet (cardiovascular):
– Vasodilation, tachycardia and lactic
acidosis
– Heart failure develops
• Infantile
– Occurs in infants (3-4 weeks old),
breastfed by thiamin deficient mothers
– Heart failure- may occur suddenly
http://www.merck.com/mmpe/sec01/ch004/ch004f.html
Riboflavin
• 2 coenzyme derivatives:
– Flavin mononucleotide (FMN)
– Flavin adenine dinucleotide (FAD)
• RDAs for males 19-70 years: 1.3 mg/day
• RDAs for females 19-70 years: 1.1 mg/day
• What foods contain riboflavin?
Functions of Riboflavin
• Flavoproteins provide most roles in the
body:
– Electron Transport Chain
– PDHC
– Beta oxidation
– Various mineral and vitamin metabolism
Riboflavin
http://www.3dchem.com/molecules.asp?ID=63
Deficiency of Riboflavin
• No clear deficiency, but can occur
– Alcoholics
– Congenital Heart disease
– Some cancers
http://www.wrongdiagnosis.com/phil/html/riboflavin-deficiency/3990.html
Vitamin B3: Niacin
• Water soluble vitamin B3
• Nicotinamide is a derivative of niacin and used to
form the coenzymes nicotinamide adenine
dinucleotide (NAD) and nicotinamide adenine
dinucleotide phosphate (NADP)
• RDAs
– Males 19-70 years old 16 mg/day
– Females 19-70 years old 14 mg/day
• What foods contain Niacin?
Functions of Niacin
• Oxidation- Reduction Reactions
– Krebs or TCA cycle
– Glycolysis
– Beta oxidation
• Non-redox reactions
– Mainly occurring in bacteria
Niacin or Vitamin B3
Deficiency of Niacin
• Usually occurring in
developing countries
• Primary deficiency: Pellagra
– Extreme deficiency in both
niacin and tryptophan
– Most common physical
attributes are dermatitis,
diarrhea and dementia
– Can be cured with supplements
• Secondary deficiency:
Alcoholism, Diarrhea and
Cirrhosis
http://www.merck.com/mmpe/sec01/ch004/ch004d.html
Toxicity of Niacin
• Sometimes used in large amounts to
reduce LDL cholesterol and triglyceride
levels and to increase HDL cholesterol
• General symptoms are flushing
Pantothenic Acid
• Once referred to as Vitamin B5
• No RDAs, but AI or Adequate intake
– Males and females >19 years: 5 mg
• What foods is pantothenic acid found in?
Pantothenic Acid
• Functions:
– Component of CoA
– Participates in Cellular Metabolisms:
• Carbohydrate
• Protein
• Lipid
Pantothenic Acid
http://commons.wikimedia.org/wiki/File:Pantothenic_acid_structure.svg
Deficiency of Pantothenic
Acid
• Burning Feet Syndrome
• Malnourished population:
– Alcoholism
– Diabetes
– Inflammatory Bowel Disease
Biotin
• Also known as vitamin B7
• No RDAs, but Adequate Intake (AI)
– Men and women >19 years of age: 30 µg
• What foods contain Biotin?
Functions of Biotin
• Considered a coenzyme with:
– Pyruvate Carboxylase
– Acetyl CoA carboxylase
– Propionyl CoA carboxylase
Biotin
http://www.chm.bris.ac.uk/webprojects2002/schnepp/biotin.html
Deficiency of Biotin
• Usually occurs when consuming raw eggs
in excess amounts
• Gastrointestinal disorders
• Pregnancy
• Genetic defects
http://mark.asci.ncsu.edu/Nutrition/NutritionSlides/38.jpg
Folate
• Water soluble B-complex vitamin
• Folic acid is the more stable form and not
found in foods or humans, but in
supplements and fortified foods
• Folate containing molecules are found in
foods and humans
• RDA for folate:
– Males and Females 14 years old+ 400 µg/day
• What foods contain folate?
Functions of Folate
• Reproduction and maintenance of cells
• Needed to make DNA and RNA
• Needed to make red blood cells to prevent
anemia in adults and children
Folic acid
http://healthlink.mcw.edu/article/984001430.html
Fig. 9-28, p. 350
Folate
Deficiency
• What can happen with
folate deficiency?
– For pregnant women,
can give birth to low
weight, neural tube
defect infants
– Infants and children can
have slow growth
– What type of anemia
may occur with both
folate and vitamin B12
deficiency?
Toxicity
• Very uncommon in both
foods and supplements
due to it is a water
soluble vitamin and can
be excreted in the
urine, but it can happen
Vitamin B12
• Methylcobalamin and 5-deoxyadenosyl
cobalamin are the forms of vitamin B12
used in the human body
• RDA for males and females 19-70 years
old 2.4 mcg/day
• What foods contain Vitamin B12 ?
Functions of Vitamin B12
• Cofactor for methionine synthase
• Cofactor for L-methylmalonyl-CoA mutase
– Cobalamin is the cofactor for this enzyme
Vitamin B12
Vitamin B12 Necessary for Folate
Function
• Methylcobalamin is required for the
function of the folate-dependent enzyme,
methionine synthase
• This enzyme is required for the synthesis
of methionine from homocysteine
Vitamin B12
Deficiency
• Pernicious anemia
• Food bound vitamin
B12 malabsorption
• Atrophic gastritis
• Who may be more
affected with vitamin
B12 deficiency?
Toxicity
• None has been seen
with food or
supplements even as
high as 1000mcg/day
Vitamin B6
• 3 forms of vitamin B6
– pyridoxal (PL)
– pyridoxine (PN)
– pyridoxamine (PM)
• The principal coenzyme factor, pyridoxal-5phosphate (PLP) has the most important
function in humans
• Must be obtained from the diet
• RDAs for males and females 19-50 years old is
1.3 mg/day
• What foods contain vitamin B6 ?
Functions of Vitamin B6
• PLP is the main cofactor in multiple enzyme
reactions for humans to function:
– Nervous System: Neurotransmitters are synthesized
with PLP- dopamine, serotonin
– Red blood cell formation: Synthesis in heme
– Niacin Formation: PLP synthesizes tryptophan to
niacin
– Hormone function: PLP binds to steroid receptors to
inhibit the binding of steroid hormones
– Nucleic Acid Synthesis: Coenzyme for mobilization in
a single one carbon metabolism
Vitamin B6
Deficiency
• Uncommon, unless
you are an alcoholic
Toxicity
• Usually when taking
the form of B6 :
pyridoxine in
supplements over an
extended period of
time