Are You Getting Rusty?
By Dr. John M Berardi, Ph.D. - Author of:
Rusty Hubcaps and Rusty
Ever notice rust on your
hands after working out? Sure you have. Plenty of guys favor those old,
slightly rusty 45-pound plates at their local gym. But have you ever thought
about why they've rusted? Or if you might be doing the same?
Living in an oxygen-rich
environment (the air is about 21% oxygen) allows you to exercise intensely,
metabolize food, and do so many other things. Heck, this very oxygen-rich
environment has helped life evolve on this planet. But while oxygen is
certainly beneficial on many levels, its presence and function comes at a
Just as the metal plates at
your gym and the floorboards of your '72 Pinto slowly oxidize (rust), so do the
cells/tissues of your body. And it's this oxidation of your bits and pieces
that some scientists think causes many of the diseases of aging. So let's go on
a little trek into your cells and see why antioxidant nutrition might be a
Next On Dateline:
"When Oxygen Goes Bad"
Whether you like it or not,
we're primarily aerobic (oxygen consuming) organisms. To put this into
perspective, under normal resting conditions, we consume around 3.5ml of oxygen
per kilogram of body mass per minute. This means that if the average 80kg
individual were to lie in bed all day, he/she would consume about 403L of
oxygen in that day. Obviously if this individual gets up to exercise, to move
around, or even simply to roll over and change the dressings on their bedsores,
the oxygen requirement would go way up. Good thing the government isn't taxing
So why such a huge amount
of oxygen consumption? Well, this huge oxygen consumption is primarily used to
drive cellular respiration, to metabolize nutrients, and to produce ATP for
energy. All of this occurs at the mitochondrial level and within this organelle
(specifically the cytochrome level of the electron transport chain), enzymes
are present to assist in the processing of this oxygen. While these enzymes have
evolved to efficiently process oxygen during the generation of energy, about
2-5% of all the oxygen flowing through this energy manufacturing warehouse
"goes bad," forming reactive oxygen species (ROS) and free radicals.
For the purposes of this
article we'll consider ROS and free radicals one in the same and refer to them
as pro-oxidants for the sake of simplicity. After all, each of these little
cellular scavengers can become the equivalent of micro sized wrecking crews
banging up your cellular parts. In more scientific terms, the chemical
structure of these pro-oxidants is such that they contain extremely volatile
unpaired electrons. These unpaired electrons readily react with cellular
components such as proteins (structural, contractile, enzymatic), membrane
lipids, and even the nucleotides within DNA and RNA, changing the structure of
these molecules. This places every part of the cell at risk for radical-induced
damage and alteration!
Bring Out the Heavy
Fortunately for us, with
all of this oxygen processing, we are in possession of both well-developed
internal (endogenous) enzymatic anti-oxidant defenses as well as the ability to
consume foods that can protect against these cellular scavengers. These defense
mechanisms step up as soon as the cell is challenged by excessive pro-oxidant
activity and attempt to maintain a favorable pro-oxidant to anti-oxidant
Exercise training provides
a good example of this principle in action. It's been well documented that
moderate intensity exercise increases pro-oxidant production. However, we all
know that exercise is good for you and in fact, protects against many of the
diseases associated with radical induced damage. So, what gives? Well, the body
responds to moderate intensity exercise training with an upregulation of the
natural anti-oxidant enzymes superoxide dismutase (SOD) and glutathione
peroxidase (GPX). Therefore, although exercise causes an increase in radical
formation, the physiological response to this actually improves the pro-oxidant
to anti-oxidant ratio.
Fish oil supplementation
provides another good example of this phenomenon. Since fish oil is extremely
susceptible to oxidation both in the body and outside of the body (that's why
it's kept in opaque containers), some researchers have reported an increase in
pro-oxidant formation with fish oil supplementation. However, don't abandon
your fish oil supplements just yet. Since the research demonstrating that fish
oil supplementation provides protection against many of the diseases of aging
is clear-crystal clear-you should be asking yourself whether something else is
going on here. Well, there is. Research has demonstrated that fish oil
supplementation actually increases the genetic expression of several genes that
protect against free radicals (Takahashi et al 2001), again creating a more
favorable pro-oxidant to anti-oxidant ratio.
Exercise Mode and
As you might have guessed,
different modes of exercise lead to different radical-generating mechanisms.
Therefore both intense strength exercise as well as intense aerobic exercise
have been shown to increase the production of pro-oxidants through three
distinct mechanisms-increased metabolic (mitochondrial) oxygen processing,
ischemic-reperfusion injury, and muscle micro-trauma/repair (otherwise known as
leukocyte radical production). These mechanisms are described below.
Endurance Athletes and
Increased Mitochondrial Oxygen Processing
As mentioned earlier, the enzymes of the mitochondria can produce pro-oxidants
during energy metabolism, even at rest. Therefore it stands to reason that
during intense aerobic activity, where oxygen processing occurs at rates 10-20
fold above resting oxygen consumption, more radicals will be generated. In
fact, this increase in oxygen consumption leads to a 2-3-fold increase in free
radical levels. While the natural anti-oxidant enzymes can normally neutralize
free radical damage at rest, during exercise the increase in oxygen radicals
may be more than these antioxidants can contend with.
Weight Training and
Ischemia is defined as
inadequate blood flow and/or inadequate oxygen delivery to the tissues of the
body. While usually used in reference to the hypoxia (low oxygen) seen during
myocardial infarction (heart attack), ischemia can also be seen in both
skeletal muscles and various organs during weight training.
The typical static or
moderate duration contractions associated with strength training can
effectively "pinch off" the skeletal muscle, not allowing blood to
circulate through this tissue. As described above, this could lead to hypoxia
and ischemia within the skeletal muscle.
As well all know, once the
contraction is over, however, blood rapidly refills the muscle, creating a huge
pump. What you might not have known is that this rapid refilling can lead to
something known as reperfusion injury. Reperfusion injury occurs, obviously, as
blood rapidly re-oxygenates a tissue. Therefore, after a muscle contraction,
blood rapidly flows back into the muscle and rapidly re-oxygenates it. Not
prepared for this rapid influx, the mitochondria, myoglobin, and hemoglobin may
form excessive amounts of pro-oxidants, thus injuring the skeletal muscle with
radical induced damage.
While the skeletal muscle
is certainly at risk for ischemic-reperfusion injury, other tissues may be at
an even greater risk. It should come as no surprise that during exercise, blood
is shunted away from internal organs and re-routed to the skeletal muscles. In
fact, at rest, 15-20% of cardiac output (or 0.75-1L of blood per min) is
shunted to the muscles. However, during maximal exercise, 80-85% of cardiac
output (or 20-21.25L of blood per minute) is shunted to the muscles. Obviously
with all this blood going to the muscle during exercise, there's less blood
going to the organs. After the exercise session, there is a large influx of
blood back into the organs and this influx may lead to the same type of
reperfusion injury described above.
Weight Training and
Muscle Micro Trauma/Repair
This final mechanism is
interesting in that it doesn't actually occur during exercise; it's a post
exercise phenomenon. As we know, intense strength exercise can lead to both
mechanical and oxidative damage in skeletal muscle. This damage includes the
loss of structural and contractile integrity as well as damage to the lipid
membranes of the muscles. After exercise-induced microtrauma (damage), there's
a period of inflammation and soreness characterized by neutrophil and monocyte
In addition, leukocytes
(white blood cells) are activated to initiate repair. Data on this phenomenon
are displayed in Muscle Masochism, Parts I and II. While these immune cells are
excellent in their role of removing damaged muscle fibers, these same immune
cells lead to free radical generation. This is necessary as the free radicals
can help clear away microscopic tissue fragments/debris. What this means is
that both the weight training session and the recovery from this session can
cause free radical-induced damage.
As an interesting side
note, it's currently unclear as to which came first, the radicals or the
damage. It seems as if there's a downward spiral effect. Acute exercise leads
to free radical production. These radicals (as well as other mechanical
factors) can cause damage to cytoskeletons, membranes, and other cellular
components of skeletal muscle. Once this damage occurs, leukocyte radical
production is initiated to clear away damaged fibers, leading to the release of
more free radicals and more radical-induced damage. And so on until the next
So How Bad Is It?
Reviewing the three
mechanisms listed above, it's scary to think about what's happening to our
muscles during and after aerobic or strength training. But remember, our bodies
do have some complex mechanisms designed to deal with alarming physiological
events. But the question remains-are these mechanisms good enough?
Most of the research
looking at the exercise and oxidation has been done in endurance athletes. In
these individuals exercise training leads to increased endogenous
("produced within") antioxidant enzyme concentrations as well as
increased activity of these antioxidants. Therefore just as VO2 max,
capillarization, mitochondrial density, and cardiac output increase in order to
facilitate future exercise bouts, so do the antioxidant defense systems. One
question remains though. With very intense exercise, do these defense systems
increase enough to balance out the increased levels of pro-oxidants? Many
researchers believe that the answer may be no.
Scott Powers, PhD and
well-known antioxidant researcher has been quoted as saying, "It is well
known that intense or prolonged exercise results in oxidative injury to
skeletal muscles…Further there is growing evidence that radicals contribute to
muscular fatigue…Therefore it's not surprising that there is strong interest in
the effects of antioxidant supplements on exercise performance."
Animal data has shown
repeatedly that muscle fatigue can be delayed in controlled in vitro muscle
preparations perfused with antioxidants. Human studies have also indicated that
increasing the concentration of endogenous antioxidants (i.e. increasing
glutathione concentrations via whey protein supplementation) as well as
providing antioxidant supplementation can improve performance. As is often the
case, however, human studies on this topic are rather equivocal
("back-and-forth") regarding performance enhancement. Still,
antioxidant benefits appear to be more than theory.
Since we specifically
discussed endurance athletes, let's address weight-training athletes.
Unfortunately, very few data have been collected in these individuals. However,
since enzymatic adaptations occur primarily in slow-twitch muscle fibers (which
are more mitochondrially dense and therefore contain more antioxidant enzymes
than fast twitch fibers), athletes with a high percentage of fast twitch fibers
may be at greater risk of radical-induced damage.
Since there's a clear
increase in pro-oxidants with intense strength and endurance exercise as well
as a decrease in plasma concentrations of vitamin E, vitamin C, coenzyme Q10
(all antioxidant vitamins/nutrients), perhaps athletes training at a high
intensity may need more than what the body can naturally provide. After all, even
those athletes consuming what's traditionally defined as a "nutritious,
well balanced diet" see these reductions in plasma concentrations of some
of the antioxidants. In this scenario, supplementing with antioxidant nutrients
may be necessary.
Rarely is Any
Physiological Phenomenon All Bad
Before we discuss which
nutrients may assist in preventing pro-oxidant induced damage in hard training
athletes, we want to caution you against developing a hatred for pro-oxidants.
Sure, the appearance of too
many pro-oxidants in the body is obviously a bad thing as these radicals can
damage important cellular components. But just like with cortisol, estrogen,
and dozens of other necessary physiological compounds, pro-oxidants in small
quantities are necessary and can even be beneficial.
Small quantities of
radicals may be beneficial to cellular communication and cellular defense. It's
well known that several intracellular messengers (cAMP, diacylgycerols, etc)
signal the onset of many cellular processes. There's now evidence that radicals
may perform similar roles. Lipid peroxidation is one mechanism by which this
In case you didn't know,
lipid peroxidation is the process by which free radicals oxidize the membranes
of different body cells. While typically seen as a negative thing, this process
of breaking down the cellular membrane is one way that the membrane renews
itself. In addition, this lipid peroxidation can release some mediators of
immune function and inflammation known as eicosanoids.
Free radicals can also
interfere with enzymes that promote the formation and secretion of
corticosteroids as well as the formation of inflammatory prostaglandins.
Additionally, free radicals
are involved in the destruction of bacteria and viruses as well. They both help
assist in the removal of these invaders as well as stimulating the gathering of
Finally, even the leukocyte
"oxidative burst" is necessary to destroy old or damaged tissue in
order to promote new tissue growth and muscle hypertrophy.
So, don't hate free
radicals altogether. In necessary quantities, they may be quite friendly. It's
only when the pro-oxidant: anti-oxidant ratio gets out of whack (as in hard
training athletes) that you need to worry about excessive cellular damage, poor
performance, and hampered recovery. This suggests that excessive antioxidant
support may actually be harmful in itself. Not only might it interfere with
some necessary and beneficial physiological processes, but also with the
potential toxicity of several antioxidant herbs, vitamins, and minerals, you
may cause a host of other problems.
So now that you understand
why you might consider taking antioxidant supplements as well as understand
that there is such a thing as too much, let's discuss some of the available
antioxidants. (Those that are marked with an asterisk deem special attention.)
Vitamins and Minerals
Vitamin A - This lipid soluble vitamin has
been shown to possess antioxidant properties, offering protection against lipid
peroxidation, oxidative damage to proteins, and LDL oxidation. While these
benefits are certainly desirable, very little research has been done in
athletes since vitamin A toxicity is likely at higher doses. Interestingly,
while plasma vitamin A decreases with exercise training, skeletal muscle
vitamin A increases. In our opinion, as long as you're getting your RDA (900ug
per day), no supplemental vitamin A is necessary or encouraged.
Beta Carotene - The carotenoids are a group of
lipid soluble molecules (including lycopene, alpha and gamma carotene,
canthaxanthin, lutein, etc), some of which are converted to vitamin A. However,
some of the carotenoids have vitamin A independent roles including radical
quenching, immune enhancement, and the induction of detoxification enzymes.
Beta-carotene and lycopene are the best studied for these properties as well as
their role in deterring cancer and heart disease. While there are very few
exercise data, exercise does reduce plasma carotenoids. Supplementation with a
combination of vitamins C, E, and beta-carotene can reduce lipid peroxidation
at rest and at different exercise intensities as well as protecting against
glutathione levels and muscle damage. We recommend supplementing with perhaps
5,000-10,000 international units daily.
Vitamin C - Ascorbic acid, is a very well
researched water-soluble vitamin that has strong antioxidant properties.
Vitamin C has the interesting ability to act as a primary non-specific
antioxidant (it removes all radicals) as well as the ability to regenerate
vitamin E. This can lead to a reduction in free radical production during
exercise as well as a reduction in muscle soreness and damage. While vitamin C
has a host of benefits, its antioxidant properties have to be weighed against
its pro-oxidant properties. You see, vitamin C has the ability to increase
dietary iron absorption. Iron is a potent pro-oxidant and linked to
cardiovascular disease, particularly in men. And in excess, vitamin C itself
can actually be a pro-oxidant. So moderate your doses. We recommend 250mg of
vitamin C 1-2x daily (in addition to what your diet provides and not in
conjunction with iron-rich meals).
Vitamin E - This lipid soluble vitamin is the
most heavily researched antioxidant vitamin as members of the vitamin E family
play roles in immunity, aging, exercise, heart disease, and cancer. For
exercisers, muscle trauma can be attenuated with vitamin E supplementation,
having favorable effects on lipid peroxidation, release of tissue enzymes, and
protein damage/catabolism. While very large doses of vitamin E can be toxic,
there is a wide therapeutic range. However, to maximize the benefits while
minimizing the risks, 400IU should be taken 1-2x per day (in addition to what
your diet provides).
Selenium - Selenium, a trace mineral
essential to natural glutathione peroxidase structure and function, can
increase endogenous GPX levels (much like the cysteine donor, whey protein).
However, whey protein supplementation has shown to also improve performance
while selenium has not. With its narrow range of toxicity, and apparent lack of
efficacy, whey protein may be better and safer than additional selenium
supplementation above what the diet can provide.
Zinc - Zinc, a trace mineral, is a
structural component of the antioxidant enzyme, superoxide dismutase (SOD; the
cytosolic form), but it's thought to have independent antioxidant properties,
including membrane and protein stabilization. Since zinc balance is often
unfavorable in athletes and zinc plays a variety of roles in physiological
function (beyond antioxidant benefits), we suggest consuming at least 11 mg
daily but not more than the tolerable upper limit of 40 mg per day.
Maganese - Maganese, a trace mineral, is a
structural component of many enzymes and acts much like zinc in that it is a
component of antioxidant enzymes (mitochondrial SOD) as well as an independent
antioxidant. Maganese has been shown to decrease oxidative brain injury, LDL
oxidation, and atherosclerosis. However, it is our opinion that 2-5mg per day,
coming from food sources, is a sufficient intake and additional supplementation
Copper and Iron - These trace minerals have many
cellular functions including antioxidant potential. However, both of these are
easily oxidized and can, in fact become pro-oxidants. Therefore the recommended
intake of 0.9-3.0 mg of copper and just 8-10 mg of iron (for men) should not be
exceeded. This iron limit may be difficult to maintain for serious carnivores
but just try not to supplement any additional iron.
Acids (Corn Oil, Soybean Oil, Flax Oil, CLA, Fish Oil) - At this point we should discuss
the pro-oxidant potential of polyunsaturated fatty acids (omega 3s and 6s).
Polyunsaturated fats become incorporated into cell membranes and due to their
relative instability, can be easily oxidized. But, as mentioned earlier, omegas
3s (and to some extent CLA) increase endogenous levels of antioxidants and
shift the body toward a better pro-oxidant: anti-oxidant ratio. In fact, some
anti-cancer benefits of special polyunsaturates may even be reduced by other
antioxidants. Therefore with all of the health benefits of omega 3s, their
pro-oxidant status is not a big concern. We suggest that >33% of total fat
intake should come from polyunsaturated fatty acids; with about half of this
intake in the form of omega 3s.
Acids (Olive Oil, Canola Oil) - Monounsaturated fatty acids are more resistant to
peroxidation than their polyunsaturated counterparts. In fact, data show that
consumption of these fatty acids can actually reduce markers of tissue
oxidation. Since monounsaturated fatty acids lower cholesterol levels, LDL
cholesterol, and LDL oxidation, they should be a substantial part of any sound
nutritional regime. We suggest that >33% of total fat intake come from
monounsaturated fatty acids as found in olive oil and peanuts.
Whey Protein - See selenium. Antioxidant
benefits come from as little as 20g of high quality, whey protein isolates per
Ubiquinone is a naturally occurring part of the electron transport chain and
antioxidant. It may act as a direct antioxidant as well as an indirect one,
regenerating vitamin E. Exercising individuals have reduced levels of
ubiquinone in the muscle. While CoQ10 supplementation can normalize muscle
levels, the data are widely mixed with some studies showing a benefit, some
showing no benefit, and others showing negative effects. Therefore we do not
support the use of CoQ10 supplementation at this time.
Alpha Lipoic Acid - ALA is an interesting molecule as
it is both lipid and water-soluble and is present in mitochondrial proteins
necessary for oxidative metabolism; is a cofactor for dehydrogenase enzymes;
enhances glucose disposal; and can scavenge numerous ROS. Research has also
shown that ALA improves mitochondrial function and therefore age associated
metabolic decline. While ALA's role in glucose disposal as well as its
antioxidant properties need to be clarified, we believe that perhaps 300 of ALA
per day can be beneficial in terms of health and body composition.
Polyphenols - Although there are very little
data examining the antioxidant effects of the following compounds in exercise,
we decided to include them here due to their popularity as well as the benefits
seen with respect to other physiological parameters. More research is certainly
needed to confirm these benefits as well as to help make recommendations as to
their intake. Food, herb, and drug interactions may be a concern with these
compounds however, for what it's worth, these compounds do have a long history
of use in other cultures.
Milk Thistle - This herb, otherwise known as
silybum marianum, contains a host of active compounds and is most well known
for their hepato-protective effects (liver protection). These effects may be
due to the antioxidant benefits of milk thistle in the prevention of lipid
peroxidation and the protection against glutathione depletion. This herb also
possesses numerous other detoxifying effects.
Pine Bark (Pycnogenol) - Pycnogenol is the main active
compound in the French maritime pine, pinus maritime. Pycnogenol has strong
free radical scavenging activity. Its benefits include the regeneration of
vitamin C, protection of endogenous vitamin E and glutathione from oxidative
stress, and up regulating oxidant-scavenging systems.
Grape Seed Extract - The polyphenols found in grape
seeds are effective in scavenging free radicals and preventing against lipid
peroxidation as well as DNA fragmentation. In addition, grape seed extract may
be able to protect against ischemic-reperfusion injury. This extract may in
fact be better than vitamin C and E at similar doses. Time (and more data) will
Green Tea - Green tea, in our opinion, should
be a staple beverage of any dietary regimen. In addition to the thermogenic,
anti-cancer and cardio-protective benefits, green tea prevents lipid
peroxidation as well as aiding in the cellular defense of the ROS released
Ginkgo Biloba - The leaves and fruit of the
ginkgo plant have been used for over 5,000 years in China. While beneficial in
the treatment of peripheral artery disease and cerebral insufficiency, ginkgo
may also be beneficial in scavenging free radicals generated during ischemic-reperfusion
injury and inflammation.
Move Over Rust-Oleum
Since the goal of this
article is to give you the necessary information to rustproof your cells,
here's a quick recap of our recommendations:
1. Total dietary fat intake
should be made up of at least 1/3-monounsaturated fatty acids (olive oil) and
1/3 polyunsaturated fatty acids (much of these coming from omega 3 fatty acids
like fish oil and flaxseed oil).
2. Consume at least 20g of
protein per day from high quality whey protein isolates.
3. Supplement dietary
intake with the following:
- Vitamin C - 250mg 1-2x per day
- Vitamin E - 400 IU 2x per day
- Beta Carotene - 5000 IU 2x per day
- Zinc - approximately 25 mg per day
- Alpha-Lipoic Acid - 300mg 1-2x per day
One thing we want you to
remember is that while many of the discussed nutrients may be very effective
antioxidants, there seems to be considerable overlap between some of their
effects, making supplementing with a laundry list of vitamins and herbs
redundant. Caution therefore should be exercised since each added supplement
may increase the risk of nutrient-nutrient interactions that can either negate
otherwise beneficial effects or even induce toxicity. Contrary to most
advertising campaigns, all interactions are certainly not synergistic (or even additive),
some may, in fact, be negative or toxic.
About the Author:
Dr. John M Berardi, Ph.D. earned his Ph.D. in Kinesiology (with a specialization in Exercise and Nutritional Biochemistry) from the University of Western Ontario.
Throughout his education, he has received training in divergent disciplines including his Health Science, Philosophy, Psychology undergraduate studies at Penn State and Lock Haven Universities, Exercise Physiology masters training at Eastern Michigan University, and strength and conditioning certification through the National Strength and Conditioning Association.
As a result of this broad educational base, Dr. Berardi’s knowledge extends beyond the bounds of physical preparation and nutrition alone.
Dr. Berardi is no stranger to the demands of elite athletics, having been successful in a number of sports including:
- Power lifting (squat 650, deadlift 600, bench 430)
- Track and field (AAU nationals in 100m and 200m)
- Rugby (medaled @ national under 21 championships)
- Bodybuilding (1st place at the 1995 Mr. Jr. USA)
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