Antioxidants in foods
By: Adiba Hasnat
So what is an antioxidant?
 There is a hint in the name antioxidant.
 In a nutshell an antioxidant is a
molecule that prevents the
oxidation of other molecules by
allowing itself to be oxidized instead
 They can be nutrients and enzymes
 Oxidation – is a chemical reaction
within a redox reaction where a
molecule loses its electrons to an
oxidizing agent
(“What are antioxidants?”, 2001)
Why do we need antioxidants in our
body?
In our normal biological processes that
undergo oxidation (such as digestion,
cellular respiration and metabolism) as
a byproduct we produce a high amount
of free radicals
Free radicals – are unstable, highly
reactive atoms or molecules free
floating in our body that have a charge
because they are missing one or more
electrons or have one too many
(Healthwise, 2009)
Free radical examples:
• O2- superoxide anion
• OH- hydroxyl radical
• transition metals such as
iron and copper
• nitric acid
• ozone
Why are free radicals so dangerous?
1. Free radicals are unstable
and highly reactive the one
that are negatively charged
will most likely “steal” the
electrons it needs from other
stable molecules in the body
(oxidization)
(Healthwise, 2009)
2. When the free radical
becomes reduced the stable
molecule it oxidized now
becomes a free radical itself
and this will onset a chain
reaction of redox reactions
CHAIN REACTION
3. This chain reaction will go
on to disrupt many
important processes that
occur in the cell and the
body in general
How do antioxidants work?
Antioxidants prevent oxidation of stable compounds by neutralizing free
radicals.
2 methods:
Chain-breaking – when a free radical initiates a chain reaction an
antioxidant molecule such as beta-carotene, vitamin C and E stabilizes the
radical by providing it with the electron it needs to become neutral. In the
process of neutralizing the free radical the antioxidant becomes oxidized
and therefore needs to be continuously replaced.
Preventive – is the method that uses antioxidant enzymes like superoxide
dismutase, catalase and glutathione peroxidase to prevent oxidation by
reducing the amount of initiating free radicals that exist in the first place.
(WebMD, 2006)
Antioxidant relation to food
Because antioxidants are
oxidized in the process of
neutralizing free radicals
they need to be constantly
replenished. They body’s
method of replenishing its
necessary supply of
antioxidants is by obtaining
these important molecules
through the foods that we
eat.
Antioxidant: Vitamin E
Vitamin E – is the most abundant
fat-soluble antioxidant in the body.
- It is a general name for all the
different isomers of tocopherol
EX. alpha-tocopherol is a specific
isomer that helps protect cell
membranes (which are mostly fatty
acids) from damage by free radicals
Foods: nuts and seeds, whole
grains, green leafy vegetables,
vegetable oil and liver oil.
(Parnes, 2002)
Antioxidant: Vitamin C
Vitamin C – is the most abundant
water-soluble antioxidant used in
the body
- It acts primarily in cellular fluid
and neutralizes free radicals in
that watery environment
Foods: citrus fruits, green
peppers, leafy green vegetables,
strawberries and tomatoes.
(Parnes, 2002)
Antioxidant: Beta-carotene
Beta-carotene – another
water-soluble antioxidant
used in the body
Target function: maintain eye
health
Foods: orange coloured foods
-- carrots, cantaloupe,
pumpkin, apricots, squash and
mango, kale, collard greens,
spinach
(Parnes, 2002)
What damaging processes do
Antioxidants prevent?
Antioxidants prevent the harmful effects free radicals have on the body’s
natural processes and functions
Oxidative stress – an imbalance between the production of reactive oxygen(a
radical) and the body’s ability to reduce the amounts of harmful radicals
present or repair the damage that they cause. (Worden, 2011)
Due to the undesired oxidization, free radicals cause:
- Destruction of cell membrane (fatty acids) and proteins
- DNA mutation caused by the oxidation of important sections of DNA
strands
- Prematurely age skin by causing the breakdown of collagen in skin cells
(Healthwise, 2009)
Risks of antioxidants
Even though there are many benefits to using
antioxidants, too much can also cause harm.
1. Too much antioxidants:
- Increase the risk of mortality
- Increase the risk of cardiovascular disease
- increased risk of hemorrhagic stroke
Why?
The body produces its own antioxidants so
adding too many external antioxidants can
disrupt the homeostatic balance your body
tries to maintain which leads to complications.
(Coila, 2011)
Benefits of Antioxidants
1. Reduce the amount of free
radicals in your body
2. Reduce the risk of developing
certain diseases such as; cancer,
heart disease, stroke, cataracts,
Parkinson's, Alzheimer's and
arthritis (Phillip, 2012)
3. Prevent direct cell damage
caused by the chain reaction that
free radicals initiate
4. Reduce the signs of aging by
preventing the oxidation of your
skin cells
5. Improves digestion
6. Relieves asthma and allergy
symptoms (Antioxidants for health
and longevity, 2009)
References
What are antioxidants? (2001). Retrieved March 20, 2013, from fitday:
http://www.fitday.com/fitness-articles/nutrition/vitamins-minerals/what-are-antioxidantswhere-can-i-find-them.html
Antioxidants for health and longevity. (2009). Health Benefits of Antioxidants. Retrieved March 24,
2013, from Antioxidants for health and longevity: http://www.antioxidants-for-health-andlongevity.com/benefits-of-antioxidants.html
Coila, B. (2011, June 27). Live strong . Retrieved March 20, 2013, from The Effects of Too Much
Antioxidants: http://www.livestrong.com/article/480352-the-effects-of-too-muchantioxidants/
Healthwise. (2009, April 14). Retrieved March 24, 2013, from What Free Radicals Do To Our Body and
Health!: http://thehive.modbee.com/node/13459
Parnes, R. (2002, November 26). Antioxidants. Retrieved from How stuff works:
http://health.howstuffworks.com/wellness/food-nutrition/facts/antioxidant4.htm
Phillip, J. (2012, October 20). Diet high in antioxidants slashes heart disease risk in women. Retrieved
March 20, 2013, from Natural news:
http://www.naturalnews.com/037402_antioxidants_heart_disease_women.html
WebMD, L. (2006, April 22). How antioxidants work. Retrieved March 20, 2013, from Web MD:
http://www.webmd.com/food-recipes/features/how-antioxidants-work1?page=3
Worden, J. (2011, November 31). Antioxidants and oxidative stress. Retrieved March 24, 2013, from Netdoctor:
http://www.netdoctor.co.uk/focus/nutrition/facts/oxidative_stress/oxidativestress.htm