Vitamin C and E supplements hampers endurance training
Vitamin C and E supplements hampers endurance training Vitamin C and E supplements may blunt the improvement of muscular enduranc...
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Vitamin C and E supplements hampers endurance training
Vitamin C and E supplements may blunt
the improvement of muscular endurance – by disrupting cellular adaptions in
exercised muscles – suggests a new study published on February 3rd in The Journal of Physiology.
As vitamin C and E supplements are
widely used, understanding if they interfere with cellular and physiological
adaptations to exercise is of interest to people exercising for health purposes
as well as to athletes.
Dr Gøran Paulsen, who led the study
at the Norwegian School of Sport Sciences, explains:
“Our results show that vitamin C and
E supplements blunted the endurance training-induced increase of mitochondrial
proteins, which are needed to improve muscular endurance.”
In the 11-week trial, 54 young,
healthy men and women were randomly allocated to receive either 1000mg vitamin
C and 235mg vitamin E (consistent with amounts found in shop supplements), or a
placebo (a pill containing no active ingredients). Neither the subjects nor the
investigators knew which participant received the vitamins or placebos.
The participants completed an
endurance training programme, consisting of three to four sessions per week, of
primarily running. Fitness tests, blood samples and muscle biopsies were taken
before and after the intervention.
Whilst the supplements did not affect
maximal oxygen uptake or the results of a 20 metre shuttle test, the results
showed that markers for the production of new muscle mitochondria – the power
supply for cells – increased only in the group without supplements.
The National Health Service (NHS)
says taking less than 540mg vitamin E and 1000mg vitamin C supplements per day
is unlikely to cause any harm.
Dr Paulsen says:
“Our results indicate that high
dosages of vitamin C and E – as commonly found in supplements – should be used
with caution, especially if you are undertaking endurance training.”
A significant trend has been
identified, but the molecular processes requires further research.
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Dr Paulsen says:
“Future studies are needed to
determine the underlying mechanisms of these results, but we assume that the
vitamins interfered with cellular signalling and blunted expression of certain
genes.”
Previous studies show that exercising
increases muscle oxidant production, which participates in the signalling
processes leading to muscle adaption. It is possible that high doses of
vitamins C and E act as antioxidants and take away some of this oxidative
stress, hence blocking muscular endurance development.