Transcript Water soluble Vitamins

Water soluble
Vitamins
Chapter 8
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Water Soluble
Vitamins
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Objectives
List the major functions and
deficiency symptoms for each
water soluble vitamin
Lit three important food sources
for each water soluble vitamin
Describe toxicity symptoms for
excess consumption of certain
water soluble vitamins
Describe some cancer causing
mechanisms, and describe how
diet and nutrition are related to
their minimization
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Water Soluble Vitamins
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Excess readily excreted from the
body
 Large amounts can be lost in
food processing and preparation
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focus on regular intake of water
soluble vitamins, which are;
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Stir fry, steam best for retaining vitamin
content
Eight B vitamins and Vitamin C
Table 8-3 Summary
B vitamins
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often found together in foods
lack of one, may indicate others are
low
function as coenzymes fig 8-1
key roles in metabolism
breakdown and synthesis of energy
containing nutrients
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B vitamins
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Many B vitamins are interdependant in metabolism (Fig 86)
 after ingestion, broken down into
free vitamins in stomach and SI absorbed in SI 50-90%
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reformed into coenzymes in cells as
needed
Intake is plentiful in our society
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Due to fortification and availability
other areas of world - health
concern
elderly / alcoholics also a concern
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long term deficiency - not clear
 short term - fatigue, other
physical symptoms related to
slowing of metabolic processes
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B vitamins
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Grains and seeds modified by
processing - milling
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crushed - germ, bran and husk
removed leaving starch containing
endosperm
flour, bread and cereals
enrich flour with thiamin, riboflavin,
niacin folate and iron
still lack B-6, E, zinc and
magnesium, and fiber
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choose whole grains
 Brown rice, whole wheat breads,
whole wheat or brown rice pasta
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Thiamin (B1)
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Used to release energy from
carbohydrates (fig 8.6)
 deficiency - beriberi (‘I cant I cant’)
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weakness, loss of appetite,
irritability
occurs when rice (white) is staple
glucose poorly metabolized primary fuel for brain and nerve
cells
occurs after only 10 days on thiamin
free diet
Thiamin in Food
pork, whole grains, soy milk,
fortified cereals, enriched flour (fig
8.7)
 RDA 1.1-1.2 mg / day
 average 150% (M) 100% (F)
poor and elderly at risk
supplements non toxic - lost in urine
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No upper limit set for intake - no extra
benefit
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Riboflavin (B-2)
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Used in many energy yielding
pathways as coenzymes (fig 8.6)
 Also in vitamin and mineral
metabolism and as an
antioxidant
 Deficiency inflammation of mouth and tongue
 dermatitis, cracking of skin around
mouth
 develop after 2 months
 occurs with niacin, thiamin and B-6
deficiency as these nutrients often
occur in the same foods
 Riboflavin in food (p 256)
 milk, enriched grains, fortified
cereal,
 RDA 1.1-1.3 mg / day
 alcoholics at risk
 no toxic indications for megadoses
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Niacin (B-3)
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Is a pair of related compounds
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pellagra - deficiency syndrome
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rough or painful skin
early symptoms - poor appetite,
weakness and weight loss
Symptoms - dementia, diarrhea and
dermatitis (skin exposed to sun)
Niacin in foods
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Co-enzyme in energy utilization and
in synthetic pathways for fatty acids
Fig 8.6
broad use - widespread symptoms
tuna, poultry, fortified cereal, wheat
bran, asparagus, peanuts (p 265)
niacin is heat stable
RDA 14 - 16 mg / day
risk with alcoholism and disorders of
tryptophan metabolism
toxic > 35 mg/day - headache,
itchy
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Pantothenic Acid
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Co enzyme for energy release
from carbohydrate, fat and
protein -fig 8.6
 forms coenzyme A
 deficiency - rare burning/tingling in feet or hands
 Pantothenic acid in foods
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present in all food
sunflower seeds, mushrooms,
peanuts, eggs
Adequate Intake 5 mg/day
alcoholism - poor diet
symptoms are likely to be masked
by other B vitamin deficiencies
No toxicity in known
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Biotin
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2 forms - active in fat and
carbohydrate metabolism
synthesis of glucose, Fatty acids,
DNA
 breakdown of Amino Acids
 deficiency - scaly inflammation of
skin
 decreased appetite, nausea,
anemia, depression, muscle pain
and weakness
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Biotin in food
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cauliflower, egg yolk, peanuts,
cheese
intestinal bacteria synthesize biotin
Antibiotics reduce absorption
raw egg whites - have the protein
avidin - binds biotin so that it is not
absorbed
Adequate intake 30 ug/day - avg 2X
relatively non toxic
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B-6
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Family of three compounds
 coenzyme for metabolism
Carbohydrate, fat and protein
 deficiency - widespread symptoms
 depression, vomiting, skin
disorders, nerve irritation, impaired
immunity
 metabolism of AA - needs B-6
 split Nitrogen from AA - synthesis of
non-essential AA
 synthesis of neurotransmitterscommunication
 1950’s infant formula - heat
destroyed B-6 - deficiency resulted
in convulsions
 synthesis of hemoglobin (O2) and white
blood cells (immunity)
 role in recycling homocysteine along
with B12 and folate - elevated levels of
homocysteine associated with CVD
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risk
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B-6 in foods
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Fig 8-8
Animal products, fortified cereal,
potatoes, milk, banana, avocado
animal sources are more
absorbable
measurement in food is difficult
RDA 1.3 - 1.7 mg/day
set high due to high protein
intake
high protein breakdown
Athletes - may need slightly more
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increased glycogen and AA use as
fuel
higher protein intake
Usually sufficient from increased
food and protein intake in athletes
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B-6 (continued)
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Alcoholism -metabolites formed in
ethanol - increase destruction of B6
 dec. absorption, and synthesis of
coenzyme as well
 liver disabled (cirrhosis and
hepatitis)
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B-6 toxicity
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2 - 6 g/day for 2 months
irreversible nerve damage
also with long term 200 mg/day
abuse in bodybuilders
symptoms - difficulty walking, hand
and foot numbness
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upper limit 100 mg/day
 B-6 tablets can be up to 500mg,
taking a toxic dose is quite easy
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Folate
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Helps in formation of DNA
 Metabolism of AA (homocysteine)
 deficiency - early phases of red
blood cell synthesis - immature cells
can not divide - because DNA is not
formed
 Form megaloblasts - enlarged cells
 macrocytic anemia - dec O2
carrying
 after 7-16 weeks on folate free diet
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Maternal deficiency - neural tube
defects in fetus - fig 8-9
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Spina bifida and anencephaly
Cancer therapy - methotrexate hampers folate metabolism
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affects rapid cell division of cancer
cells as well as intestinal and skin
cells
hair loss, Diarrhea, vomiting
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Folate in foods
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Green leafy veg., organ meats,
sprouts, orange juice
 food processing and preparation
destroys 50-90% of folate in food
(heat)
 RDA 400 ug/day DFE-(Dietary
Folate Equivalent)
 synthetic folate absorbs a lot
better than natural folate
multiply intake by 1.7 for dietary
folate equivalent - DFE
Many have inadequate intake - this
has gotten a lot better since mandatory
enrichment of grain products in 1998
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Folate enrichment now
mandatory
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Women of child bearing age of
concern
Pregnant women - 600 ug / day
As are the elderly and alcoholics
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B - 12
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Family of compounds that
contain mineral cobalt
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complex means of absorption
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synthesized by bacteria and fungi
B-12 released by digestion - food
interacting with stomach acid
free B-12 binds with intrinsic factor
B-12 / intrinsic factor complex
absorbed in Small Intestine
30-70% of dietary B-12 absorbed
without I Factor only 1-2%
absorbed
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95 % of deficiencies due to
absorption problems
decline in intrinsic factor and
absorption with age
Require monthly injections of B-12
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B-12 functions
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Variety of cellular processes
conversion of folate to active form
 maintenance of myelin sheaths that
insulate nerve fibers
 patchy degeneration paralysis...death
 Pernicious Anemia - weakness,
sore tongue, back pain, apathy, tingling
in extremities
 3 years for nerve destruction which is irreversible
 Generally starts after middle age
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• 10-20 % of older adults
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infants breast feeding from vegan
mothers that are B12 deficient
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long term nervous system problems
brain growth, spinal cord,
intellectual development
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B - 12 in food
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Meat, milk, eggs, seafood
 Fortified soy milk
 RDA 2.4 ug/day
 Average intake 2-3 times RDA
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Provides enough for 2-3 years
storage in liver
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takes 20 years without B-12
absorption to exhibit nerve
destruction
 Vegans, elderly at risk
 Supplementation non toxic
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Vitamin C
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Most animals make vitamin C
from glucose
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absorbed in SI - 70-90%
50 % absorbed with mega dose
Role in synthesizing collagen
(protein)
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connective tissue, bone, teeth,
tendons, blood vessels,
wound healing
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water soluble antioxidant
 Reduces formation of
nitrosamines (cause cancer)
 Maintain folate and vit. E function
 Enhances iron absorption
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toxicity of vitamin C due to over
absorption of iron
vital for function of immune
system
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Vitamin C
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Dr. Linus Pauling - 1g 
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common cold - may decrease
duration but not incidence
Large dose eliminated in urine
absorption saturated at 200mg/day
Vit C in Food - fig 8-11
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Red and green peppers, cauliflower,
brocolli, cabbage, fruits
lost in processing
• heat, iron, copper, O2 exposure
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RDA 75-90 mg/day (smokers -add
35 mg a day to RDA)
Average intake twice the RDA
deficiency - scurvy 
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20- 40 days without vit C
Weakness, opening of healing
wounds, bleeding gums, pinpoint
hemorrage
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Toxicity of Vitamin C
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Probably not toxic below 1g
 regular consumption of high doses
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Hemochromatosis
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over storage of iron
mega-dose - alert physician
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stomach inflammation, diarrhea, iron
toxicity
can alter medical test results for
diabetes
Fig 8-12,13 review- vitamins in
foods
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functions, deficiency, toxicity,
absorption Table 8-3
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Choline
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Latest addition to the list of
essential nutrients - not yet
classified as a vitamin
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Choline is part of acetylcholine a
neurotransmitter
Choline is also part of phospholipids
(lecithin)
and participates in some aspects of
homocysteine metabolism
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Found in milk, liver, eggs and
peanuts
 Average intake twice the RDA of
425-550 mg/day
 Vitamin like compounds
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carnitine, inositol, taurine and lipoic
acid are required for proper
metabolism
but are not essential in the diet, as
they can be manufactured in the
body
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