Join Shoe Clinic on Facebook
Look through the Sock it to Us entires and vote your favourite by clicking the Like button.
Be the first to hear about new products in store,
enter our online competitions, meet Shoe Clinic
team members and much more!
Click the "Like" button below to join us
(Can't see a button? You already like our page!)
|
Marnie's column
Shoe Clinic are proud to introduce Marnie Oberer. She is a nutritionist and athlete and has been the host of Eating Well on TV One for the past two years. She is a trained dietitian and has a degree and two postgraduate diplomas from the University of Otago. By 28 Marnie had set up her own business consultancy, advising high performance athletes and teams. Marnie started competitive aerobics and caught the ‘marathon bug’ running in Australia, UK and USA.
Column 31, August 2010
Running free radicals – is there a need for antioxidant supplements?
I’m sure by now most of you have heard of ‘free radicals’.
They’re the atoms or molecules - often seen as the ‘bad guys’ - that contain at least one unpaired electron making them unstable and highly reactive.
In the human body these free radicals can damage tissue, and are believed to accelerate the progression of cancer, cardiovascular disease, and age-related diseases.
Antioxidants (eg vitamins A, C, E and selenium) can reduce oxidative damage caused by free radicals in the body.
Exercise and free radical formation
Most people agree that exercise improves health; therefore it seems ironic that regular, strenuous exercise actually increases free radical production.
In moderate running:
One of the worlds’ leading experts on exercise and immunology, David Nieman - also a marathoner/ultramarathoner – says the average runner doing around 30km’s perweek shouldn’t worry about free radicals, as the body produces enough of it’s own antioxidant enzymes to deal with them.
In fact he says “the more you exercise, the more your body turns into a strong fortress against the onslaught of free radicals”.
In endurance running:
Nieman does however admit to concerns about the health of frequent marathoners and ultramarathoners who face a tremendous amount more oxidative stress and immune dysfunction.
His LA marathon study found that postmarathon infections were significantly higher in those who trained more than 60 miles (112km) per week.
Are all free radicals bad?
Scott Powers, a physiologist and free radical researcher, claims that free radicals “aren’t all bad”, and have at least two important functions in the body.
Firstly, they fight off invading infections. Secondly, during exercise they signal themuscle to make adaptive changes, therefore playing a key role in “the training effect”.
According to Powers, most exercise produced free radicals never leave the muscles, so they never get to the tissues and organs where they’re known to do damage.
He says the free radicals to worry about are the ones that infiltrate your body via environmental pollutants, such as cigarette smoke.
Should I take an antioxidant supplement then?
So it seems exercise, especially endurance exercise, increases free-radical production, though the long term effect of these exercise-induced free radicals (as compared to environmental free radicals) is still not certain.
We know that antioxidants neutralize free radicals, so it seems logical that taking an antioxidant supplement could act as an insurance policy against oxidative damage.
In theory, yes, but its not that simple… and in fact a recent review of scientific literature showed that if anything, people in trial groups given the antioxidants betacarotene, vitamin A and vitamin E showed increased rates of mortality, and there was no indication that vitamin C and selenium had a positive or negative effect.
Without getting into a very detailed scientific explanation, when an antioxidant binds with a free radical it will become a free radical itself (though a less damaging one), and can only be regenerated by another (sometimes very specific) antioxidant.
This means that a fresh supply of different antioxidants is required. So if you only get one type of antioxidant (ie vitamin E) then you are actually not doing yourself any favours.
In addition some antioxidants may only work in certain parts of the body. For example, vitamin C is concentrated in blood plasma, connective tissues and within the cytoplasm of cells.
So each antioxidant is highly comparmentalised each having its own zone of defense, thus you need a large range of antioxidants.
Increasing fruit and vegetable intake still the best known strategy
This could partly explain why numerous researches prove the effectiveness of higher intakes of fruit and vegetables – which contain thousands of these life saving antioxidants - in reducing the risk of developing several types of cancer, cardiovascular disease and stroke.
Their antioxidant strength alone did not however – in a large European study – fully explain the reduced mortality in those eating high levels of fruit and vegetables, and it was concluded that many other biological effects from fruit and vegetables may also be responsible.
So it seems a lot more research is required into the effects of exercise-induced free radicals, and the best method to counteract any oxidative damage.
And while the effects of taking antioxidants in supplement form is controversial, I would recommend eating a minimum ‘5 plus a day’ of fruit and vegetables a day without reservation!.
Marnie Oberer
|
|
|
