Water Soluble Vitamins
Susan Algert
Water Soluble Vitamins
Thiamin
Riboflavin
Niacin
Vitamin B-6
Folate
Vitamin B-12
Pantothenic Acid
Biotin
Vitamin C
Fat vs. Water Soluble Vitamins
Water Soluble
Fat Soluble
Lymph via CM
Transport
Directly to
blood
free
Storage
Circulate freely
In cells with fat
Excretion
In urine
Stored with fat
Toxicity
Possible w
supplements
Requirements
Every 2-3 days
Likely w
supplements
Every week
Absorption
Require carrier
Water soluble vitamins
• Susceptible to heat
• Kidney removes and excretes excess
• Vitamin C, thiamin and riboflavin are
especially susceptible to heat and alkilinity
• Hydrophilic and water will leach them from
vegetables
• Preferred methods are steaming, stir-fry and
microwave
B vitamins act as co-enzymes
Thiamin
• Sulfur containing and nitrogen containing
rings attached to carbon atoms
• Part of nerve cell membranes—synthesize
and regulate neurotransmitters
• Functions in energy metabolism—vitamin
portion of TPP; plays role in
decarboxylation and helps form
Acetyl Co A from pyruvate
Thiamin
• Dietary Recommendation
RDA for adult men is 1.2 mg for women is 1.1
mg per day
Higher needs in pregnancy; most diets with
variety and adequate energy supply ample
thiamin
Thiamin
• Deficiency
• Heavy alcohol consumption with
inadequate food consumption ; alcohol
interferes with absorption (WernickeKorsakoff syndrome); poor and elderly at
risk for not eating sufficient energy
Thiamin Deficiency/Toxicities
• Beri Beri
• Impaired muscle contractions
• Impaired cardiac function, edema and
muscle twitches
• Decreased neurological function and
memory loss
Thiamin food sources
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Pork
Whole and enriched grains
Fortified cereals
Most animal foods contain little
thiamin
Riboflavin
• Involved in energy metabolism; part of two
co-enzymes, FMN and FAD
• Participate in citric acid cycle and beta
oxidation and electron transport
• Remove ammonia during deamination of
some amino acids
• Associated with antioxidant glutathione
peroxidase
Dietary Recommendations for
Riboflavin
• RDA is 1.1 mg for women and 1.3 mg for
men per day
• Pregnancy and lactation increase energy
needs and need for riboflavin
Food Sources
• Most plant and animal foods
• Milk and milk drinks and yogurt supply
about 15% in the American diet
• Fortified cereals, bread and bread products
contribute about 10%
• One of four vitamins added to enriched
products
Deficiency/Toxicity
• Deficiencies are rare although some people
may take in marginal amounts
• Drug and alcohol users and restricted
caloric intake
• Ariboflavinosis
• Toxicity– not observed
Niacin (Nicotinic Acid)
• Made from tryptophan; essential nutrient if
protein intake is inadequate
• 60 mg tryptophan converts to 1 mg niacin
• RDA is 14-16 NE/day for adults
• NE include preformed and niacin derived
from tryptophan
Functions of Niacin
• NAD and NADP play key role in
oxidation-reduction reactions
• Helps convert pyruvate to lactate
• Coenzyme component that
participates in over 200 metabolic
reactions
Food Sources
• Preformed niacin from meat, poultry fish
and enriched or whole grain products
• Beef and processed meats are substantial
contributors in U.S. diet
• Stable when heated
• Tryptophan found in protein rich animal
foods
Niacin deficiency
• Pellagra
• Epidemic in southwest in early 1900’s as
corn became staple; niacin is bound by
protein
• Deficiencies found in southeast if subsisting
on diet of corn, molasses and salt pork
• International health issue
Medicinal uses of niacin
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Lowers blood levels of LDL cholesterol
Raises HDL cholesterol
Doses of 1,300 mg to 3,000 mg per day
Side effects include liver abnormalities
UL for niacin is 35 mgms per day
Taken only under medical supervision
Biotin
• Function critical in energy metabolism ;
TCA cycle and gluconeogenesis
• Bound to enzymes as a co-factor and
requirement is small
• No RDA; AI is 30 micrograms/day
• Deficiency rare and toxicity not seen
Pantothenic Acid
• Component of Co enzyme A; involved in
energy metabolism
• No RDA; AI is 5 mg/day
• Deficiency is rare (dermatitis, hair loss,
depression)
• Toxicity is rare
Vitamin B-6
• Forms include pyridoxal, pyridoxine, and
pyridoxamine and phosphorylated forms
• Functions include support of over 100
different enzyme reactions including :
transfer of amino group, carboxyl group or
water
Enzymes support protein metabolism, blood
cell synthesis, CHO metabolism,
neurotransmitter synthesis
Dietary Recommendations and
Sources
• RDA is 1-3 mg/day; TUL =100 mg/day
• Deficiency symptoms include weakness,
insomnia, depression, irritability
• Sources include fortified cereals, meat, fish,
poultry, starchy vegetables and noncitrus
fruits
• Heat sensitive; most people get enough
B6 Toxicity and Medicinal Use
• Megadoses of up to 2,000 mg/day can cause
irreversible nerve damage
• Large doses used to treat PMS or in stress
formulas
• UL is 100 mg/day
• High doses taken only under medical
supervision
Folate
• Converts vitamin B-12 to coenzyme form
• Supports DNA synthesis and cell replication
and growth
• Along with B12 and B6, may decrease risk
for heart disease
• Tetrahydrofolic acid (THFA) is coenzyme
with five active forms
Dietary Recommendations and
Deficiency
• RDA is 400ug/day (is it most prevalent
vitamin deficiency?)
• TUL is 1000 ug/day
• Deficiency causes macrocytic anemia, NTD
• Toxicity masks vitamin B12 deficiency
• Dietary folate equivalents= higher
bioavailability of supplemental folate vs.
folate in foods
Folate in foods
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Fortified ready to eat cereals
Dark green leafy vegetables
Asparagus
Broccoli
Orange juice
Wheat germ
Legumes
Vitamin B-12-Cyanocobalamin
• Cobalamin or cobalt containing compounds
• Transfers methyl group from folate
coenzyme THFA to make active form; B12
deficiency leads to folate deficiency
• Dietary recommendations 2.4 ugm/day for
men and women
• Atrophic gastritis decreases bioavailability
in adults over 51
Vitamin B-12 Absorption
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R-protein
pancreatic enzymes
Intrinsic factor
Bacteria in the stomach
Gastric acid production
B12 in the diet
• RDA is 2.4 ugm per day; B12 not present in
plant foods
• Animals store excess B12 in tissues
• Mixed foods with animal protein contribute
most B12
• B12 deficiency usually occurs due to
impaired absorption
• Vegans at risk
Deficiency disease is pernicious
anemia
• Megaloblasts and macrocytes rather than
normal red blood cells
• Brain abnormalities and spinal cord
degeneration which can be lethal
• Pernicious anemia attacks parietal cells and
diminishes intrinsic factor and stomach acid
Functions of Vitamin C
• Antioxidant—donates electron minimizing
free radical damage; Recycles oxidized
vitamin E for reuse
• Collagen synthesis
• Stabilizes reduced form of folate enzyme
• Enhances absorption of non-heme iron
• Helps synthesize carnitine
• Proper functioning of immune system
Vitamin C deficiency/toxicity
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Scurvy
Breakdown gums and joints
Bone pain, diarrhea, fractures, fatigue
UL is 2,000 mg per day
Can possibly enhance oxidation when
consumed in high doses without other
antioxidants
Dietary Recommendations
• RDA is 90 mg for men and 75 mg for
women per day
• Smokers require +35 mg per day
• Food sources include potatoes, citrus fruits,
broccoli, leafy greens
• Highly vulnerable to heat and oxidation
Vitamin like compounds
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Choline
Inositol
Carnitine
Lipoic acid