Antioxidants
: activate antioxidant enzyme
systems to destroy free radicals and
reduce reactive oxidizing species. (to
convert into less damaging molecules
that can be excreted from body)
Minerals
Food and drink sources
: donate electrons to
complete the outmost
molecular orbital of the free
radical to neutralize free radical
and terminate chain reactions
Vitamins
Fat-soluble
Vitamin A:
2 forms:
retinoids
carotenoids
Carotenoids: PROVITAMIN A
from plant foods; ~50 common in human diet
20-40% absorption enhanced with fat
stored in adipose tissue or liver, converted to retinal +
retinol
ex. beta (β)-carotene, most biologically active carotenoid in
the body
found in orange veggies/fruits
Retinoids: preformed vitamin A
90% stored in liver, little in adipose
tissue
forms:
-retinol - reproduction, mostly in liver
-retinal - vision
-retinoic acid - growth + development
Causes: food and supplement intake
Symptoms: low appetite, enlarged liver, bone defects,
headache
Types:
TOXICITY (Retinol):
acute - single large dose
chronic - regular high intake over a period
tetratogenic - intake through supplements during pregnancy
FOOD SOURCES:
animal/protein-rich foods(50% of intake each)
liver, fish oil, egg yolk, cheese, etc.
ANTIOXIDANT ROLES (β-Carotene):
unclear functions in humans
neutralizes free radicals (especially lipids in cell membranes +
LDL)
-may reduce risk for cancer + atherosclerosis
weaker than vitamin E
NON-ANTIOXIDANT ROLES (β-Carotene):
immune system - anti-inflammatory at moderate doses
skin - protection against sun damage
eyes - protection against age-related degeneration
DEFICIENCY (β-Carotene):
no known symptoms
low intake associated with increased heard disease +
cancer
TOXICITY (β-Carotene):
no known symptoms
hypercarotenemia - fat under skin turns yellow at high
intake
FOOD SOURCES (β-Carotene):
plant foods, green + orange vegetables (kale, yam,
carrots)
red + orange fruits (mango, cantaloupe)
fortified margarine + cereals
Selenium
2 forms:
-- Selenocystenine (active)
-- Selenomethionine (storage)
ANTIOXIDANT
ROLES
NON-ANTIOXIDANT
ROLES:
acting as
Thyroid
Hormone
Deficiency:
- common in areas
with selenium depleted soils
Keshan's
disease
TOXICITY:
usually due to intake of
supplements with more
than 1 mg per day
DEFICIENCY (Retinol):
Vision
night blindness - retina
-may progress to blindness
xerophthalmia (dry eye) - cornea
-cause of blindness in ~0.5 million children
Growth
children growth failure
abnormal jaw growth, leads to poor dental health and nutrient
intake
-deficiency in youth
Mucous membrane health
reduced mucous production
-keratinized cells, decreased absorption and susceptible to
infection
Immunity
children suffer from measles
-severity depends with deficiency
ANTIOXIDANT ROLES:
retinoids, not considered
NON-ANTIOXIDANT ROLES
vision - for rods and cones in retina; cornea
growth, development, reproduction - specific PRO coding
mucous membrane health in epithelial tissue - protection against
infection in eyes, urinary tract, skin, etc.
immunity - immune cell production (ex. T-cells)
Water-soluble
Selenium spares vitamin E use by
reducing free radicals to be neutralized
Vitamin E:
membrane flexibility
ANTIOXIDANT ROLES:
cell membranes: neutralize free radicals & maintain
membrane integrity
nuclear + mitochondrial membrane: protects DNA +
other components from oxidation damage
protection against heart
disease
NON-ANTIOXIDANT ROLES:
Cause: overconsumption through supplements (or food,
but unlikely)
Symptoms: muscle weakness, fatigue, nausea, diarrhea
TOXICITY:
could increase effects of anticoagulants and lead to
uncontrolled bleeding
Food source:
plant oils (corn, soybean, almond)
seeds and nuts (hazelnuts, sesame,
sunflower)
whole grains
-very little in egg yolk and liver
Protects cell membrane by acting as a
cofactor for glutathione peroxidase (GPx)
enzyme (coenzyme: B-vitamin, riboflavin)
Reduces number of free radicals to
conserve Vitamin E
Converts T4 (thyroxine) to
- a thyroid hormone with greater biological activity
that regulates BMR, growth and body
temperature
T3 (triiodothyronine)
(heart muscle loses its ability to pump blood
from the heart to the body effectively)
Cardiomyopathy
(might lead to joint deformity)
Severe joint pain
Brittle nails
Hair loss
Neurological damage
Fatigue
Irritability
Vegan/vegetarianism
Vegans and retinol:
cannot get sufficient amounts through diet
supplements may be a source, but consumption through
food is strongly recommended
Vitamin C:
~80% absorbed at intakes <100 mg,
50% at 1250 mg
2 stable forms: ascorbic acid
(reduced) + dehydroascorbic acid
(oxidized)
excess excreted through urine
act as a reducing agent/ electron
donor
ANTIOXIDANT ROLES:
stops free radical damage by donating an e-
acts in ICF/EXC compartments
reduces nitrosamine formation in stomach
(possibly cancer-causing)
keeps folate coenzyme intact
NON-ANTIOXIDANT ROLES:
enhances iron absorption: keeps them in
reduced oxidation state (Fe2+)
-- increases non-heme iron absorption in plant
foods
collagen synthesis: maintains connective tissue
integrity, prevent bruising, heal wounds
DEFICIENCY:
Scurvy
symptoms: weakness, joint pain, bleeding gum,
teeth loss, failure of wounds to heal,
(hemorrhage on face and limbs)
petechiae
reversal of symptom seen with intake of 100 mg ~5
days
Widespread tissue breakdown
due to reducing property of vitamin C for collagen
synthesis
TOXICITY:
Megadose: >10 times DRI, excess excreted
through urine and may cause diarrhea
symptoms: fatique, nausea, muscle weakness
FOOD SOURCES:
mostly plant foods (veg/fruits, especially citrus)
Free radicals
Examples
superoxide radical
hydroxyl radical
nitric oxide
Positive impacts
destroy harmful
substances in
immune system
Formation
formed when an atom has an odd, unpaired electron in its
outmost atomic orbital
Negative impacts
highly reactive & unstable
damage cell membranes, cellular proteins, blood LDL
lipoproteins and nuclear DNA
may cause cancer
environmental factors
pollution
radiation exposure
exposure to (excessive) UV light
exposure to toxic substances, tobacco smoke
biological factors
naturally produced due to metabolism of
nutrients which are oxidized
produced when oxygen accepts an extra
electron released in metabolic reactions
free radicals initiate chain reactions to be stabilized
FOOD SOURCES:
protein from plants and animals
seafood
liver
Brazil nuts
banans
rich vitamin
content, vitamin ratio is even higher when water
is removed.
Fruits (especially dried fruits):
rich in phenolic compounds
which have antioxidant properties
Herbs:
ginger
basil
cinnamon
pepper
paprika
chili
onion
Beverages
fruit juices
apple juice
grapefruit juice
tomato juice
cranberry juice
pomegranate juice
green tea
rich in polyphenol
black coffee
example: immune response, ATP production, oxidizing
macronutrients
most common example: in electron transport chain
coconut water
berries (strawberry, blueberry, cranberry)
olives
fruits that do not oxidize (eg:mango, kiwi) contains
more antioxidants than fruits that oxidize easily
(eg: apple, pear, banana)
Pro-oxidant: can release iron from storage PRO
cause cellular damage like free radicals
Rebound scurvy: occurs when high vitmin C intake
decreases suddenly
Kidney stones: stress on kidney when concentrating urine to
excrete excess
easily lost when processed/cooked
excessive heat, prolonged exposure to air, and baking
soda
moderate cooking can enhance β-carotene availability;
adding little oil to vegetable juice increases absorption
1~2 years until deficiency
symptoms appear in adults
Types:
acute - single large dose
chronic - refular high intake
tetratogenic - intake through supplements during
pregnancy
easily lost in food preparation/ processes:
destroyed by heat, exposure to O2, metal, light
Preterm infants at risk the most
DEFICIENCY:
low transfer from mother to fetus, needs more for
growth
infant placed in incubator, high O2 environment, stress
on lung membranes and needs more vitamin E
Hemolytic anemia
caused by loss of RBC (red blood cell) membrane
integrity
RBC cannot carry sufficient O2 to cells for energy
acai juice
Vitamin C enhances selenium absorption
High-risk individuals
alcoholics: especially with nutrient-poor diet
smokers: >35 mg/day to combat free radical damage
burn patients: collagen for skin repair
is converted
to
in
body to be
utilised
β-Carotene
retinol
