Antioxidants
- nature's little helpers
Putting out fires
So how do antioxidants work? Think of them as fire-fighters,
putting out the fires created by unstable particles,
called free radicals.
A free radical is an atom in the body that is damaged
and missing one or more electrons, making it unstable.
Free radicals roam around, searching for other atoms
from which to steal electrons. When a stable atom has
an electron stolen, it in turn becomes an unstable free
radical. This starts a chain-reaction of electron-stealing
throughout the body.
In come the fire-fighters, in the form of free radical
scavengers. These atoms have extra electrons that they
donate to free radicals, stopping the chain reaction.
Antioxidants are a major source of free radical scavengers.
Free radicals can damage mitochondria (the energy powerhouse
of a cell), rupture cell membranes and damage DNA, thereby
altering or destroying cell function.
The body can normally cope with low levels of free radicals
but high levels may initiate or contribute to premature
ageing, atherosclerosis (a disease of the arteries) and
heart disease, cancer, cataracts, arthritis, infertility
in men and other degenerative diseases.
While oxygen is essential to life, it can also damage
cells. The chemical process that occurs when oxygen damages
cells is called oxidisation and it is this process that
creates free radicals.
You can see oxidisation in action in your kitchen when
fats become rancid or the flesh of an apple turns brown.
This process is occurring in your body too.
Oxygen is not the only substance that causes oxidisation.
These also contribute to the process:
- Environmental pollution
- Cigarette smoke
- X-rays or radiation
- Sunlight
Considering that all of these factors are frequently
present in our contemporary way of life, it is virtually
impossible to prevent the production of free radicals
in our bodies. What we can do, however, is top up our
levels of antioxidants to combat the activity of free
radicals and therefore prevent disease. However, antioxidants
cannot prevent disease alone: hereditary and other factors
may be present that contribute to the development of
disease.
Oxidisation and cholesterol
Antioxidants,
such as Vitamin E, beta-carotene and lycopene (the red
pigment in tomatoes) may help to stop damage occurring
to the blood vessel walls by preventing the oxidisation
of cholesterol within the body.
Oxidisation of
'bad' LDL cholesterol in the bloodstream is thought
to play a key role in the development of fatty streaks
and atherosclerosis in artery walls – and
the accompanying increased risk of angina, heart attack
and stroke.
Antioxidants are
found in certain vitamins, minerals, enzymes and nutrients.
They are also found in carotenoids, the pigments in
fruits and vegetables that give them their red, yellow
and orange colours. Another source of antioxidants
are phytochemicals – non-vitamin
compounds that are found in all fruits and vegetables.
Research has estimated that the risk of heart disease
and cancer is considerably lower in people who consume
five to seven serves of antioxidant-rich fruit and vegetables
every day.
To make sure that you are getting enough carotenoids
and phytochemicals, try to eat three different colours
of fruit and vegetables every day to provide you with
a range of colour pigments.
Vitamins
| Vitamin |
Antioxidant action |
Food sources |
| Vitamin A |
Helps prevent the formation of free
radicals by bonding to oxygen molecules. Promotes
germ-killing enzymes, destroys carcinogens and
is necessary for healthy mucous cells. The carotenoid
beta-carotene is a form of Vitamin A and is one
of the most powerful antioxidants to be found. |
Carrots, broccoli, squash, melon,
spinach, other deep yellow and orange fruits and
vegetables and other green, leafy vegetables. The
stronger the colour of the fruit or vegetable,
the higher the carotenoid content. |
| Vitamin C |
Guards against harmful reactions
occurring within cells and traps free radicals
before they enter cells. Recommended dosage is
between 600 and 1,000 mg per day. |
Citrus fruits and juices, strawberries,
kiwi fruit, tomatoes, broccoli, spinach, potatoes
and capsicum. |
| Vitamin E |
Vitamin E improves the use of oxygen
within the body and protects the coating around
cells from free radical attack. Between 200 and
600 IU recommended daily. |
Vegetable oils, seeds, nuts, wheat
germ, whole grain breads and cereals, green leafy
vegetables. |
Minerals
| Mineral |
Antioxidant action |
Food sources |
| Selenium |
Stimulates increased antibody response
to germ infection. Works very well in conjunction
with Vitamin E. Between 100 and 200 mcg recommended
per day. |
Brewer's yeast, meat, oysters, salmon,
tuna, cashews and whole grains. |
| Zinc |
Required for protein synthesis and
collagen formation. Promotes a healthy immune system.
Between 25 to 30 mg recommended per day. |
Fish and other seafood, legumes,
soy products and whole grains. |
Enzymes, nutrients and fatty acids
| Enzyme |
Antioxidant action |
Food sources |
| Alpha lipoic acid |
The body produces its own alpha lipoic
acid, a vitamin-like fatty acid that plays a large
role in energy production within cells. |
Red meat, potatoes, carrot, spinach. |
| Gamma-Linoleic Acid (GLA) |
An omega-6 fatty acid. Hydrogenated
vegetable oils, margarine or a high-fat diet can
block the body's ability to convert food to GLA.
The body creates its own GLA from linoleic acid,
found in vegetable oils. |
Evening primrose oil, black currant
seed oil and borage oil. |
| L-Cysteine |
Used by the liver and lymphocytes
to detoxify the body. Works best when taken with
vitamin E and selenium. |
Garlic |
| L-Glutathione |
An amino acid that works as a detoxifier
to rid the body of free radicals produced from
metals, drugs, cigarette smoke and alcohol. Studies
have shown that L-Glutathione is not increased
in the body by taking supplements. |
Present in most plant and animal
food sources. |
| Superoxide dismutase (SOD) |
An enzyme that revitalizes the cells
and reduces the rate of cell destruction. Removes
the most common free radical, superoxide, and helps
the body use zinc, copper and manganese. Studies
have shown that SOD is not increased in the body
by taking supplements. |
Barley and wheat grasses, broccoli,
brussel sprouts, cabbage and most green plants. |
| Coenzyme Q-10 |
Helps the body produce energy at
a cellular level. Protects and strengthens the
heart and slows the shrinking of the thymus (one
of the body's main immune organs) which occurs
with age. People over 35 could consider using a
Coenzyme Q-10 supplement. |
Fish, red meat, eggs, spinach some
grains and beans. |
Carotenoids
These are the red, yellow and orange pigments found
in fruits and vegetables. As well as having antioxidant
properties, they are thought to be potent cancer fighters.
Beta-carotene (Vitamin A) is one of the most powerful
antioxidants (see above).
| Carotenoid |
Antioxidant action |
Food sources |
| Lycopene |
Gives tomatoes their red colour.
Lycopene is linked to a lower risk of prostate
cancer in men. In one study, men who ate at least
ten servings of tomato-based foods every week had
a 45 per cent reduced risk of developing prostate
cancer. May also reduce cholesterol oxidisation. |
Tomatoes, tomato sauce, tomato puree. |
| Lutein and zeaxanthin |
Linked to eye health in the elderly. |
Spinach and broccoli. |
Phytochemicals
Phytochemicals are found in all fruits and vegetables.
Early research is speculative but shows them to be potential
cancer protectors. They seem to interact with every step
of the cancer process, by slowing, stopping or reversing
cancers.
| Phytochemical |
Antioxidant action |
Food sources |
| Flavonoids |
Include catechins. |
Green and black tea, red wine. |
| Isoflavones |
Include
phytoestrogens, plant hormones that are very
weak versions of the human hormone oestrogen. However,
due to the way in which phystoestrogens in soy
may react with certain treatment medications,
people who have had breast cancer should always
consult with a doctor before eating soy products
or other phytoestrogen foods. |
Soy foods. |
| Lignans |
Lignans are a type of phytoestrogen
(see above). High lignan intake is associated with
reduced rates of breast, prostate and colon cancer
in population studies. |
Plant foods, soy beans, sesame seeds
and flax seed. |
Other phytochemicals include indoles and isothiocyanates
(mainly responsible for broccoli's ant-cancer reputation),
organosulphur compounds in garlic and onions, monoterpenes
in citrus fruits and caraway seeds, saponins in soybeans,
nuts and chickpeas, and cruciferous chemicals with anti-cancer
properties in broccoli, cabbage, cauliflower and brussel
sprouts.
Supplements vs. the real thing
Foods provide a range of antioxidants and may be better
for you than taking single vitamin supplements in tablet
form, such as vitamin E or vitamin C tablets. Antioxidants
work together and help each other in the body, so the
combination of antioxidants obtained naturally from foods
works more effectively than single supplements. You may
like to choose an antioxidant supplement formula that
contains a range of antioxidants, but remember that vitamin
supplements should never replace a healthy diet.
It's also important not to go overboard. Studies have
shown that extremely high doses of antioxidants may damage
cells in much the same way free radicals do.
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Reproduced with permission from CalorieKing.com.au. All material copyright CalorieKing.com.au |
