Download Chapter 4: The Human Body: From Food to Fuel

Vitamins
Readings:
– Chapters 9 & 10
1
Outline
- Overview
- Bioavailability - minimizing losses
- Classification
- Fat versus Water soluble
- Function, Recommendations, Sources,
Deficiency, Toxicity
- Fat Soluble - A,D,E and K
- Water Soluble - B vitamins and C
2
Overview
Characteristics of
Vitamins: “vital to
life”
• do not yield energy
• organic
• only required in
small amount (mg
or mg)
3
Overview
What to study…
• know the characteristics and functions,
effects of deficiency and toxicity for each
• be able to identify or list rich sources of each
• need to know specific RDA for folate and
Vitamin C
4
Understanding Vitamins
True or False?
– if a little is good, then a lot is better
– vitamins are energy boosters
– vitamins work exclusively of one another
Vitamins in Foods
– all food groups are natural sources of various
vitamins
– also founds in enriched and fortified foods
5
Bioavailability
• the rate and extent to which a nutrient is
absorbed and used
Determinants
• efficiency of digestion & time of transit
through the digestive tract
• previous nutrient intake & nutrition status
• other foods consumed at the same time
• method of preparation
• sources of the nutrient
6
Minimizing Vitamin Losses
• vitamins are organic therefore susceptible to
destruction by:
HEAT, UV LIGHT or OXIDATION
• prevent losses through:
– refrigeration of fruits and vegetables
– storing cut vegetables, fruits, and juice in airtight
containers to reduce oxidation
– wash fruits and vegetables before cutting
– steam vegetables in small amounts of water, avoid
over cooking
7
Classifications of Vitamins
• classified according to solubility in fat
versus water
Fat Soluble = Vitamins A, D, E, and K
Water Soluble = B Vitamins and Vitamin C
8
Fat vs. Water Soluble
Water Soluble
Fat Soluble
Vitamins
B Vitamins, C
A, D, E, & K
Absorption
directly into blood
with lipids into lymph
Transport
none required
require protein carriers
Storage
free in aqueous
compartments
in cells associated with
fat
Excretion
readily via kidneys
not readily
Toxicity
only from supplements
more likely
Requirement
frequently (every 1- 3
days)
periodically (weeks to
months)
9
Vitamin Absorption
10
Vitamin A
Vitamin A is found in two forms:
• retinoids
– derived from animal sources
– preformed Vitamin A (biologically active from)
– includes retinal, retinol, and retinoic acid
• carotenoids
– derived from plant sources
– pro-vitamin form, converted to retinoid form by
body as needed
– examples:
 b-carotene (pro-vitamin),
– lycopene, lutein (nonprovitamin) may have other
beneficial roles (antioxidant, vision, cancer
prevention)
11
Vitamin A: Functions
1. Vision
• retinal forms part of molecule called rhodopsin
– compound found in cells of the retina
– important for converting a light stimulus to an
electrical stimulus
– allows brain to interpret visual information
• Fig 9-7
12
Vitamin A: Functions
2. Protein Synthesis and Cell Division
• promotes differentiation of:
- epithelial cells
- goblet cells
- T lymphocytes
13
Vitamin A: Functions
3. Reproduction and Growth
• retinol important for sperm development in
men
• required for normal fetal growth
• important for bone remodeling and growth
– assists osteoclasts by helping enzymes
that breakdown bone
14
Vitamin A: Functions
3. Antioxidant:
• carotenoids only!!!
• donates an electron to oxygen free
radicals to prevent OFR from stealing
them from other molecules, halts the
chain of free radical production
Definition of free radical…
– unstable and highly reactive atoms or molecules
that have one or more unpaired electron
– steal electrons from other molecules such as LDL,
membrane lipids, proteins and others
15
Free Radicals
Antioxidant

DNA
Vitamin A: Recommendations
Recommendations
• expressed as RE (retinol equivalents) or RAE
(retinol activity equivalents)
• 1 RAE = 1 mg of retinol
– Supplemental Betacarotene - 2ug = 1 RAE
– Dietary Beta-carotene - 12ug = 1 RAE
– Dietary Carotenoids - 24ug = 1 RAE
• Adult RDA = 700 – 900 RAE per day
17
Vitamin A: Sources
1 cup sweet potatoes
½ cup pumpkin
½ cup carrots
100% of RDA =
18
Vitamin A: Deficiency
• one of most common nutrient
deficiencies worldwide
• leading cause of preventable blindness
• deficiency due to lack of intake requires
one to two years to develop to develop
adults, develops more quickly in
children
19
Vitamin A: Deficiency
Symptoms & Consequences
• first detectable sign = night blindness
• increased incidence of infectious disease
• xeropthalmia
– total blindness due to drying and hardening of the
cornea
• keratinization
– epithelial cells begin to secrete keratin
• hard inflexible protein in finger nails and hair
– decreased mucous production
– skin becomes dry, rough and scaly
20
Vitamin A: Toxicity
• vitamins A & D are the most toxic vitamins
• only the retinoid form is toxic
– Upper Limit 3000 ug RAE as retinol
– Over-consumption of carotenoids is not harmful because
conversion to retinoids is regulated
• Carotenodermia - harmless orange coloration
Symptoms
• nausea, vomiting, diarrhea
• loss of appetite, fatigue, insomnia
• headaches, blurred vision
• dry itchy skin, rashes, nose bleeds
• teratogenic: causes abnormal fetal development & birth defects stored for years limit intake during child bearing years
– women need be careful if on Retin-A or Accutane for acne discontinue at least 2 yrs before becoming pregnant
21
On completion of your dietary analysis, you
notice that your Vitamin A intake is 4x
(400%) of the DRI.
- What are the potential health effects of
this excess consumption?
- What other information do you need in
order to justify your answer above?
Vitamin D: Functions
• also called calciferol or cholecalciferol
• regulates the concentrations of calcium &
phosphate in the blood
• promotes bone mineralization
• supports immune system function
• regulates cellular differentiation, proliferation,
and apoptosis (cell death)
23
Vitamin D: Calcium Regulation
•
works in conjunction with parathyroid
hormone and calcitonin
• increases blood calcium (Ca2+) levels by
three mechanisms:
- stimulates Ca2+ absorption from the small
intestine
- reduces Ca2+ excretion from kidney
- (by increasing re-absorption)
- mobilizes Ca2+ from bone
24
Vitamin D: Recommendations
& Sources
Recommendations
• Adult = 5 mg/day (200IU), requirements
increase after age 50 (10 mg/day)
– Current research suggests this should rise
significantly (25 mg/day)
Sources
• can be synthesized in the body from
cholesterol with exposure to UV light
• rich food sources include dairy products, fatty
fish, fortified margarine, fortified soy and rice
25
beverages, fortified cereals
Vitamin D: Sources
fatty fish, dairy,
fortified cereals
UV Light
skin
pre-vitamin D
liver
kidneys
active Vitamin D26
Vitamin D: Synthesis
27
Vitamin D: Deficiency
• in children results in the disease rickets
– bones fail to calcify
– legs bend out because the bones are
softened and weak
28
Vitamin D: Deficiency
• in adults contributes to the development of
osteomalacia (soft bones)
– occurs in conjunction with a low calcium intake
– young women with repeated pregnancies at risk
• also increases risk of osteoporosis
(decreased mineral density)
– also occurs in conjunction with a low calcium
intake
29
Vitamin D: Toxicity
• Vitamin D and Vitamin A are the most toxic
vitamins
• Toxicity usually only occurs with supplements
• UL - 2000 IU (50mg) / day (may be
conservative)
• leads to increased blood calcium =
hypercalcemia
– tissues (kidney, heart, lungs, liver) become calcified
– leads to death
• other symptoms include nausea, vomiting, loss
of appetite, fatigue, kidney damage
30
• Sun exposure does not result in toxicity
Vitamin D & Cancer?
• Canadian Cancer Society recommends
Canadians consume a supplement of 1000 IU
Vitamin D during fall & winter
• Epidemiology:
– inverse correlation between colon cancer mortality
and UV exposure
– mixed results from studies examining correlation
between dietary Vitamin D or serum Vitamin D and
cancer incidence & mortality
31
Vitamin D & Cancer
• Is there biological evidence of a role of
Vitamin D in cancer protection?
– experimental studies have found that that colon
cells express receptors for Vitamin D & calcitriol
inhibits growth of cancer cells
• What are the mechanisms?
–
–
–
–
anti-proliferative effects
stimulates cellular differentiation
promotes apoptosis
reduces angiogenesis
32
Vitamin E: Functions &
Recommendations
• also called atocopherol
• acts as an
antioxidant
– prevents oxidation
of polyunsaturated
fatty acids and other
lipids and Vitamin A
– may reduce the
oxidation of LDL
and help lower risk
of cardiovascular
disease
33
Vitamin E:
Recommendations
•Adults = 15 mg TE/day (tocopherol equivalents)
•Sources
vegetable oils
(canola, safflower,
corn, olive)
sunflower seeds
sweet potatoes
prawns
& shrimp
Others: salmon, almonds, pistachios, soy beans,
enriched cereals
34
Vitamin E: Deficiency
• rare in healthy adults
– Though smoking destroys vitamin E
– Also destroyed by oxygen, metals, light and repeated
frying
• in premature infants results in erythrocyte
hemolysis (rupture of cell membrane)
– leads to hemolytic anemia
– red blood cells burst open
– corrected with Vitamin E treatment
• prolonged deficiency causes neuromuscular
dysfunction
– poor muscle coordination, impaired reflexes
– impaired vision and speech
35
Vitamin E: Toxicity
• rare, effects less severe than Vitamin A or D
toxicity
• usually occurs with supplements
• upper limit is 65x greater that RDA
• very high doses may interfere with the blood
clotting actions of Vitamin K or enhance
actions of anti-clotting medications
• More damage if individual has a vit K
deficiency as well as very high vit E intake
– Risk of hemorrhage
36
Vitamin K: Functions
• necessary for blood clotting
– ‘koagulation’
– activates prothrombin,
the precursor to thrombin
– thrombin is an enzyme
required for synthesis of
blood clots
– also important for other
reactions in formation of a
blood clot
37
Vitamin K: Functions
• important for the
synthesis of bone
proteins
– lack of Vitamin K
results in abnormal
protein production
which bone minerals
cannot bind to
– adequate intakes may
reduce risk of hip
fractures
39
Vitamin K: Recommendations &
Sources
Recommendation
• Adult RDA = 90 - 120 mg/day
Sources
• made by intestinal bacteria
– this meets about ½ of body’s needs
• significant food sources include dark green
leafy vegetables (kale, spinach, turnip
greens, broccoli, romaine lettuce) cauliflower,
cabbage, and soybean products
40
Vitamin K Sources
41
Vitamin K: Deficiency
• primary deficiencies rare as average intake is
sufficient and it is resistant to cooking
• secondary deficiency may result from:
– conditions that disrupt fat absorption
– antibiotics that destroy colonic bacteria that
synthesize Vitamin K
– new born infants have a sterile gut and are usually
given a single dose of Vitamin K at birth to prevent
hemorrhagic disease
• results in hemorrhagic disease (unchecked
bleeding), may be fatal
42
Vitamin K: Toxicity
• rare, though may occur with
supplements
• reduces the effectiveness of anticoagulant drugs used to prevent blood
clotting
• symptoms include:
– jaundice, red blood cell hemolysis, and
brain damage
43
The B Vitamins
• act primarily as
coenzymes
• work as catalysts
• required for many
energy-producing
metabolic reactions
• Often found together
in foods, a lack of one
may indicate others
are low
– Poor, elderly and
alcoholics at risk for
deficiency
44
Vitamin B12
Vitamin B6
Niacin
Thiamin
Biotin
Folate
Riboflavin
B vitamins in concert…
Pantothenic
Acid
45
Thiamin (Vitamin B1): Functions
• part of coenzyme TPP(thiamin pyrophosphate)
– important for de-carboxylation reactions (removal
of CO2)
– needed to convert pyruvate to acetyl CoA
glucose
pyruvate
TPP
acetyl CoA + CO2
• found on nerve cell membranes, important for
nerve cell function
• RDA is roughly 1 mg per day, slightly higher
during pregnancy and lactation
• average intake of Canadians meets or
46
exceeds recommendation
Thiamin (Vitamin B1): Sources
• found in small amounts in many foods,
DRI easily met with a well-balanced diet
• destroyed by heat
1 slice of
watermelon or
½ cup cooked
peas provides
about ¼ of
RDA
pork and pork
products are
exceptionally
rich sources
47
Thiamin (Vitamin B1):
Deficiency
• deficiency results in Beri Beri (Sinhalese for
“I can’t, I can’t”)
Symptoms
q
q
q
q
weakness and fatigue
enlarged heart
cardiac failure
apathy
q
q
q
q
poor short term memory
confusion, irritability
muscle paralysis
nerve degeneration
• can be characterized by edema (called wet
Beriberi) or by muscle wasting (called dry
Beriberi)
• no toxicity symptoms have been reported for
thiamin
48
Riboflavin (Vitamin B2): Functions
• forms part of coenzymes FAD and FMN
• participates in oxidation / reduction and deamination reactions
• associated with antioxidant performance of
enzyme glutathione peroxidase
• required (with iron & Vitamin B6) to convert the
amino acid tryptophan to the B vitamin niacin
• required to convert Vitamin B6 to its coenzyme
form
• RDA about 1 mg, most Canadians meet or
exceed.
49
Riboflavin (Vitamin B2): Sources
• small amounts in many foods, easy to
meet DRI with a well-balanced diet
• destroyed by UV light
1 cup yogurt
 ½ RDA
3 oz liver
exceeds RDA
½ cup cooked
mushrooms 
¼ RDA
50
Riboflavin (Vitamin B2):
Deficiency
• deficiency is rare, but usually occurs in
combination with other nutrient deficiencies,
called ariboflavinosis
• causes inflammation of membranes of mouth,
skin, eyes, and digestive tract
– inflamed eyelids, sensitivity to light
– sore throat, cracks in upper lips and at corners of
mouth
– Glossitis (swollen tongue) and dermatitis
• no toxicity symptoms have been reported for
riboflavin
51
Niacin (Vitamin B3): Functions
• other names include nicotinamide & nicotinic acid
• part of coenzyme NAD required for many
reactions of energy metabolism, especially
metabolism of glucose, fat, and alcohol
2 ATP
C
C
C
C
Glucose
C
C
C
C
C
C
C
C
NAD+
NADH + H+
RDA  12-16 mg NE /day
2 Pyruvate
52
Niacin (Vitamin B3): Sources
• can be synthesized from amino acid
tryptophan
– 60 mg tryptophan = 1 mg niacin
– requires Riboflavin, Iron, and Vitamin B6
• diets rich in high quality protein never
lack niacin
Best sources per kcal:
• spinach
• mushrooms
• chicken breast
• liver
• fish (cod, halibut, tuna…)
53
Niacin (Vitamin B3): Deficiency
• results in pellagra,
“mal de la rosa”
Symptoms (4 “D’s”)
Dermatitis
Diarrhea
Dementia
Death
54
Niacin (Vitamin B3): Deficiency
Populations at risk:
– alcoholics
– protein poor diets centered on corn
• 70% of niacin in corn unavailable for
digestion and absorption
• high leucine interferes with conversion of
tryptophan to niacin
55
Niacin (Vitamin B3): Toxicity
• non-toxic if from Niacin naturally occurring in
FOOD
• large doses (1,300 - 3,000 mg/day) used
pharmacologically to treat high cholesterol
• dose of 250 mg/day can produced side
effects, including:
– niacin flush
– headaches, nausea, glucose intolerance, blurred
vision, liver damage, and peptic ulcers
• upper limit of 35 mg/day
56
Pantothenic Acid: Functions &
Sources
Functions
• forms part of CoEnzyme A
• involved in over 100 metabolic reactions
including synthesis of lipids,
neurotransmitters, steroid hormones, and
hemoglobin
Sources
• “pantos” = everywhere
Both deficiency and toxicity are rare.
57
Biotin: Functions
Functions
• forms part of a coenzyme responsible
for replenishing oxaloacetate in the
TCA cycle (metabolism of carbs and fat)
• important for gluconeogenesis, fatty
acid synthesis, and breakdown of
certain fatty acids and amino acids
58
Biotin: Sources
Sources
• widespread in many foods:
– liver, egg yolks, soy beans, fish, whole grains
• protein avidin in raw egg white prevents
absorption
• synthesized by colonic bacteria, but not
absorbed
Both deficiency and toxicity are rare.
59
Vitamin B6: Functions
• part of coenzyme PLP which is required for
protein metabolism:
– Transamination of amino acids
– synthesis of niacin from tryptophan
– synthesis of neurotransmitters, hemoglobin, & DNA
• required for the synthesis of white blood cells
• important for steroid hormone activity and
cognitive function
• converts homocysteine to cysteine
– High homocysteine correlated with heart disease
risk
• RDA  1.0 - 1.5 mg / day
60
Vitamin B6: Sources
• ample amounts provided by protein rich
foods
• easily destroyed by heat
1 medium
potato or 3
oz chicken
 ¼ RDA
Best sources per kcal:
• spinach
• broccoli
• carrots
• tomato juice
• squash
1 medium
banana 
½ RDA
61
Vitamin B6: Deficiency
• rare, alcoholics and the elderly most at risk
• drugs may interfere with Vitamin B6 (e.g. INH
used to treat tuberculosis)
Symptoms
• nerve damage, depression, confusion
• impaired immune function
• microcytic anemia (“micro” = small, “cytic” =
cell)
62
Vitamin B6: Toxicity
• stored in muscle thus can accumulate (unlike
other water soluble vitamins)
• only occurs with supplements
– Sometimes abused by bodybuilders
– taken to treat PMS, carpal tunnel syndrome or
sleep disorders
– no scientific evidence to support use!
• symptoms include fatigue, depression,
headache, numbness and muscle weakness,
convulsions, and permanent nerve damage
63
Folate: Functions
• also called folacin or folic acid
• part of coenzymes in energy metabolism
• required for synthesis of DNA, important in cell
division
– necessary for fetal development during pregnancy
• required for synthesis and development of red
blood cells and other rapidly dividing cells
• activates Vitamin B12
• converts homoecystine to methionine with
Vitamin B12,
64
Folate: Recommendations &
Sources
Know these values
for the exam!
Recommendations
• Adult: 400 mg per day
• During pregnancy: 600 mg per day
Sources
• abundant in legumes and many vegetables
• destroyed by heat and oxygen
• fortification of cereal grains required since
1998
65
Folate: Sources
Best sources per kcal:
• black-eyed peas
• lentils
• okra
• asparagus
• kidney beans
• tomato juice
• broccoli
• spinach
½ cup
asparagus 
1/3 RDA
1 cup raw
spinach  ¼
RDA
½ cup navy
beans  1/3
RDA
66
Folate: Deficiency
• one of most common nutrient deficiencies in
North America
• may result from a variety of potential causes:
–
–
–
–
inadequate intake
inadequate folate absorption
increased folate requirements
impaired folate utilization (associated with Vitamin
B6 deficiency)
– altered folate metabolism (drug interactions)
– excessive folate excretion (prolonged diarrhea)
67
Folate: Deficiency
Symptoms
• megaloblastic anemia
– “mega” = large, “blast” = immature cell
– also called macrocytic
– red blood cells remain large and immature
because of impaired cell division
– leads to weakness, fatigue, irritability and
headache
• other symptoms include glossitis and mental
confusion
68
Folate: Deficiency
69
Folate: Deficiency during
Pregnancy
• leads to neural tube defects in the
developing fetus
– abnormalities of the spine, brain, or skull
• e.g. spina bifida, anencephaly (part of brain
missing)
• supplements generally recommended during
pregnancy (under a physicians supervision)
– synthetic form is better absorbed than food form
70
Folate: Deficiency during
Pregnancy
71
Folate: Toxicity
• can MASK a Vitamin B12
deficiency
– early symptoms of a B12 deficiency
also include megaloblastic anemia
– too much folate prevents these
early symptoms from developing
72
Vitamin B12: Functions
• absorption of Vitamin B12 requires a
substance called intrinsic factor
• contains the mineral cobalt
• forms part of coenzymes
– assists in break down of fatty acids and amino
acids
• maintains myelin, a protective sheath around
nerves
– protects nerve fibers and promotes their normal
growth
• involved in bone cell activity & metabolism
73
Vitamin B12: Functions
• activates folate
• works with folate to synthesize red
blood cells
• important in synthesis of DNA and RNA
• with folate converts homocysteine to
methionine
Folate (active)
Folate (inactive)
Vitamin B12
homocysteine
methionine
74
Vitamin B12: Sources
Recommendations
• RDA = 2.4 mg per day
• Daily Value = 6 mg per day
Sources
• only found in animal products
– e.g. meats, fish, poultry, dairy, eggs
• added to some fortified cereals
• NOT available from fermented soy or sea
algae or yeast grown on a Vitamin B12 rich
medium
• destroyed by microwave cooking
75
More Information: http://www.cc.nih.gov/ccc/supplements/vitb12.html
Vitamin B12: Deficiency
• average intake of Canadians > RDA
• stored in liver and recycled
– may take several years for symptoms to develop
• concern for vegans: require supplements!
• secondary deficiency due to lack of intrinsic
factor
– called pernicious anemia
– common in older individuals with atrophic gastritis
that have decreased production of stomach acid
and intrinsic factor
76
Vitamin B12: Deficiency
Symptoms
• megaloblastic anemia (acute)
– as with a folate deficiency
– leads to fatigue, irritability, etc…
– masked by a high folate intake
• neurological symptoms (chronic)
– creeping paralysis of nerves
– begins at extremities and works up spine
– may result in permanent nerve damage and
paralysis
• no toxicity symptoms reported for Vit. B12
77
Vitamin B12
Vitamin B6
Niacin
Thiamin
Biotin
Folate
Riboflavin
B vitamins in concert…
Pantothenic
Acid
78
Vitamin C: Functions
• acts as a water based antioxidant
– re-activates Vitamin E (lipid based)
– prevents oxidation of compounds in cells
and body fluids
– neutralizes free radicals in polluted air and
cigarette smoke
79
Vitamin C: Functions
• acts as a cofactor in many reactions
– required for synthesis of collagen
• structural protein of connective tissue
and forms matrix for bones and teeth
– with iron, converts amino acids proline
and lysine to their hydroxy form
– necessary for synthesis of carnitine,
serotonin, norepinephrine, and thyroid
hormone (thyroxin)
80
Vitamin C: Functions
• other functions include:
– facilitates function of immune cells
– deactivates histamine
• chemical compound of the immune system that
mediates the allergy response
– enhances iron absorption
• captures non-heme iron and keeps it in a
reduced form (ferrous iron) that is more easily
absorbed
Recommendations (know for exam!)
30-3581 mg
mg/day smokers = +______
mg/day women = 75
men = 90
_________
_________
Vitamin C: Sources
• many animals can synthesize vit C, but NOT
HUMANS
All of the following provide  100% of the RDA
 ¾ cup cooked broccoli
 ½ cup red bell pepper
 1 kiwi
 1 cup grapefruit juice
 1 sweet potato
 1 cup strawberries
 1 large orange
 1 cup Brussels sprouts
Best source per kcal!
82
Vitamin C: Deficiency
• results in scurvy
Symptoms
–
–
–
–
–
–
–
–
begin if intake drops to < 10 mg/day
bleeding gums, loss of teeth
pinpoint hemorrhages
muscles degenerate, bones soften, skin roughens
increased infections
hysteria and depression
microcytic anemia
sudden death due to massive internal bleeding
83
Vitamin C: Deficiency
84
Vitamin C: Toxicity
• 100 mg/day saturates tissues
• minimal absorption or increase in blood
concentrations if intake > 200 mg/day
• low risk of adverse effects if intake is below
2000 mg/day
• greater than 2000 mg/day may lead to:
–
–
–
–
nausea, abdominal cramps, diarrhea, nosebleeds
interference with anti-clotting medications
gout, kidney stones
pro-oxidative effect if iron intake is excessive
• Hemochromatosis - over storage of iron
– rebound scurvy?
85
RDA for
men
90 mg
supports
metabolism
30 mg
limited
absorption
200 mg
adverse
effects
3000 mg
female
smokers
110 mg
10 mg
prevents
scurvy
100 mg
tissues
saturate
75 mg
125 mg
RDA for
male
women
smokers
2000 mg
adult UL
Is Vitamin C a Cure for the
Common Cold?
• proposed by Linus Pauling (Nobel prize winner in
Physics)
– claimed megadoses of Vitamin C prevented and cured
the cold
– also proposed that Vitamin C could prolong life of
cancer patients
• does research support these claims? NO!
– however, a Vitamin C intake > 1 g/day MAY decrease
the duration of a cold by one day
• mechanisms?
– anti-histamine actions?
– protect from immune cell Oxygen Free Radicals?
87
Vitamin Supplements??
• Supplements may be beneficial, and improve health of
population
– Multivitamin has lowest risks for toxicity and good general benefits
– While real food is better, population seems to be adverse to
increasing fruit and vegetable intake
• Most important
– folate during child bearing years
– B12 for vegans and those over 50
• Do not take more than recommended
• Take with food, or just after a meal
• Megadoses
– Vit E - shown to be have minimal impact
– Vit C - may reduce symptoms for common colds
– Vit D - could be very beneficial, more research required.
88
Matching Exercise
Vitamin C
can be synthesized from the amino
acid tryptophan
Biotin
important for the differentiation of
lymphocytes, goblet cells &
epithelial cells
Niacin
Folate
Vitamin A
Riboflavin
excess may mask a Vitamin B12
deficiency
protects against damage from
oxygen free radicals
enables amino acids to be used for
energy
needed to replenish oxaloacetate in
the citric acid cycle