Antioxidants: Combating Aging and Disease
Copyright 2006 Sylvia Riley
Wouldn't we all like to age gracefully (if at all for that
matter!) and ward off the wrinkly signs and ill symptoms for as
long as possible. Keys to longevity may be more accessible than
we think, and it appears our diets play a critical role.
Antioxidants are the knights in shining armor that subjugate the
attack of free radicals in the body, the hazardous molecules
that damage cells and procure aging and disease. Though
antioxidants are produced naturally in the body, these decline
with age, hence an increasing need to acquire them from the
foods in our diet.
Before examining antioxidants more closely, it is important to
take a look at the free radicals they serve to neutralize.
Free Radicals
Free radicals are created as by-products in our use of oxygen
during metabolism such as the burning of food for energy. They
are essentially oxidant molecules that are missing an electron
and seek to restore themselves by targeting nearby cells in an
attempt to recover this electron, potentially harming enzymes,
DNA, proteins and cell membranes in the process. This damage can
mutate cells and alter cell function, increasing the risk of
numerous diseases and chronic conditions including arthritis,
diabetes, cataracts, cancer, heart disease and stroke. Free
radical damage is implicated in the onset of aging and its
degenerative symptoms and diseases.
As well as generated within the body, free radicals come from
environmental sources such as pollution, radiation, unhealthy
foods, bacteria, viruses, cigarette smoke and UV light.
Antioxidants
Antioxidants serve to mitigate the harmful effect of free
radicals by giving up an electron and stabilizing them in the
process. Although we produce many of our own antioxidants within
the body, food provides an essential source for these key
players of our defense system. Vitamins, minerals and
phytonutrients all have antioxidant properties. The most common
examples include vitamins A, C and E, selenium and zinc,
carotenoids, flavonoids, co-enzyme Q10, alpha-lipoic acid and
glutathione.
As there are many different types of free radicals in the body a
variety of antioxidants are required to protect against them.
Antioxidants function best as a team, with each other and other
nutrients and phytochemicals, which is why incorporating a wide
range of plant foods into your diet is recommended.
Phytochemical groups such as flavonoids and carotenoids
correspond to the colour, taste and smell attributes of plants,
hence eating a rainbow array of vegetables and fruits can offer
a diverse selection of these potent antioxidants.
Antioxidant Rich Foods
Foods especially high in antioxidants include berries, plums,
pomegranates, oranges, spinach, green tea, avocado, kale,
broccoli, peas, onions, grapes and pure chocolate.
Scientists at the USDA (United States Department of Agriculture)
have developed a rating scale that measures the total
antioxidant capacity of a given food. This is known as the ORAC
score (Oxygen Radical Absorbance Capacity).
Of 40 common fruits and vegetables measured by the USDA, top
ranking scores were those of prunes(5770), raisins (2830),
blueberries (2400 - highest of all fresh foods with other
berries close behind), kale (1770), spinach (1260), Brussels
sprouts (980), plums (949), alfalfa sprouts (930), broccoli
florets (890), beetroots (840), oranges (750 ), red peppers (710
) and red grapes (739).
Pure cocoa surpasses all these foods with a whopping score of
26,00 units, more than 10 times the prestigious blueberry
(though one is likely to eat far less in quantity). The
extraordinary goji berry from Tibet also has outstanding
antioxidant capacity with a score of 18,500 units; hardly
surprising as they contain 500 times more vitamin C than oranges
and even more beta-carotene than carrots!
According to studies on animals and human blood at the Human
Nutrition Research Center on Aging at Tufts in Boston, high-ORAC
foods may slow aging processes in the body and brain. Results
found that high ORAC foods such as blueberries and spinach could
increase the antioxidant power of human blood by 10-25%, prevent
loss of long-term memory and learning ability in middle-aged
rats, and protect rat blood vessels against oxygen damage.
Antioxidants and Aging
As we age, free radical levels rise and yet the body falls short
in producing necessary amounts of antioxidants to meet this
challenge. For example, cells generate more of the oxidants
hydrogen peroxide and superoxide, yet levels of the necessary
antioxidant glutathione required to neutralise these decline.
The Free Radical Theory of Aging, first proposed by Harman in
1954, is supported by cross-species examination of animals with
regard to life span, free radical damage and antioxidant
defence. For example, the white-footed mouse lives about twice
as long as the house mouse (8 versus 4 years), and is found to
generate less oxidants and have higher levels of antioxidants.
As Beckman and Ames write in The Free Radical Theory of Ageing
Matures (1998), 'Together, interspecies comparisons of oxidative
damage, antioxidant defences, and oxidant generation provide
some of the most compelling evidence that oxidants are one of
the most significant determinants of life span.'
Very recent evidence comes from a study on dogs at the
University of Toronto by Dr. Dwight Tapp and colleagues who
found that 'old dogs that were on an antioxidant diet performed
better on a variety of cognitive tests than dogs that were not
on the diet. In fact, the dogs eating antioxidant-fortified
foods performed as well as young animals'.
Additional research by Dr. Rabinovitch and his team, studying
aging at the University of Washington, Seattle, found that mice
engineered to produce high levels of an antioxidant enzyme
(catalase) lived 20 per cent longer and had less heart and other
age-related diseases than controls.
In light of the role free radicals play in the onset of aging
and disease, it is important to ensure our diets include a rich
and diverse supply of antioxidants. These protective agents can
be found abundantly in vegetables, fruits, nuts and seeds and
are particularly high in superfoods.