european college of sport science

OP-NU01 Nutrition 1
ADMINISTRATION OF AN ANTIOXIDANT MULTI VITAMIN/MINERAL SUPPLEMENT REDUCED TRAINING INDUCED IN-
CREASES IN VO2MAX IN WELL TRAINED SUBJECTS
SKAUG, A., SVEEN, O., RAASTAD, T.
ØSTFOLD UNIVERSITY COLLEGE, HALDEN, NORWAY, NORWEGIAN SCHOOL OF SPORT SCIENCES
Introduction: Antioxidant supplements are widely used by athletes on both top and recreational level. However, the notion that oxidative
stress during exercise may be an important stimulus for the adaptive response to endurance training [1, 2], has questioned the value of
taking antioxidant supplements in this population. Consequently, the aim of this study was to investigate the effect of an antioxidant
supplement on training induced changes in VO2max in well trained subjects.
Methods: In a double-blinded placebo controlled design a total of 40 amateur soccer players were randomised into a placebo group or
an antioxidant supplemented group (SUP), and 28 of the participants completed the study. The SUP group (n=13) ingested 4+4 capsules
per day of a combined antioxidant and vitamin/mineral supplement (LifePak) and the placebo group (n=15) took a similar amount of
capsules containing lactose. The supplementation period lasted for six weeks, and before and after the participants were tested for skin
caretonid score and VO2max. During the supplementation period all subjects continued their normal training.
Results: Six week supplementation with the antioxidant vitamin/mineral supplement increased skin caretenoid score by 20±7% while no
changes in skin caretenoid score was observed in the placebo group. VO2max increased by 7.5±2.2% in the placebo group while no
changes was observed in the SUP group. The relative increase in VO2max was significantly higher in the placebo group than in the SUP
group.
Discussion: The antioxidant vitamin/mineral supplement used in this study reduced training efficiency by blocking the training induced
increase in VO2max. Although possible mechanisms behind this finding was not investigated, this result supports the idea that administration
of large amounts of antioxidants may reduce the signalling activity in pathways dependent on the formation of reactive oxygen or
nitrogen species.
1. Gomez-Cabrera MC et al. J Physiol 2005; 567 (Pt 1):113-120
2. Gomez-Cabrera MC et al. Am.J Clin.Nutr. 2008; 87 (1):142-149
MAGNESIUM – DIETARY INTAKE, SUPPLEMENT USE AND SERUM CONCENTRATION IN ELITE YOUNG GERMAN ATH-
LETES
BRAUN, H., KOEHLER, K., ACHTZEHN, S., PREDEL, G., THEVIS, M., MESTER, J.
GERMAN SPORT UNIVERSITY COLOGNE
Introduction: Magnesium (Mg) plays an important role in many cellular processes. This might explain why Mg supplement use is still
widespread in the athlete community (Braun et al., 2009), even though dietary magnesium intake seems adequate for most athletes.
Since data for young athletes is rare, the aim of this study was to compare dietary Mg intake, Mg supplement use and serum Mg concentrations
in young athletes.
Methods: Between January 2007 and October 2008, 306 athletes visited the German research centre of elite sports for a medical examination.
Two hundred fifty athletes reported their dietary situation using a validated 7 d food & activity record. On the morning following the
recording period fasting blood samples were taken. A questionnaire regarding the frequency of supplement use was provided in advance
by mail. Complete data was available for 195 (age 16.3 ± 2.8 y, male n = 99, female n = 96) athletes.
Results: Sixty-five (33 %) athletes took magnesium as dietary supplement in the past 4 weeks before the medical examination. Mean
dietary magnesium intake (without supplements) was higher in supplement users (SU: 567 ± 196 mg/day) compared to non-users (NU:
485 ± 204 mg/day) (p < 0.01). However, dietary Mg density was similar (SU: 206 ± 47 mg/1000 kcal; NU: 199 ± 61 mg/1000 kcal). Mean
serum levels were 0.86 ± 0.07 mmol/l (SU) and 0.87 ± 0.08 mmol/l (NU) respectively. Additionally those who consumed Mg supplements
on a daily basis did not have elevated serum Mg levels (n = 8; 0.87 ± 0.06 mmol/l). While energy intake was significantly correlated with
Mg intake (r = 0.68, p < 0.001), we found no association between Mg intake and serum Mg (r = 0.02).
Discussion: In the present study, we found decreased serum magnesium concentrations only in a few cases. However, it seems that an
optimal serum Mg concentration for (young) athletes has not been defined (Fogelholm 1995). Mean Mg dietary intake were above the
German RDA and increased with energy intake. In agreement with others (Fogelholm et al., 1991) we found that Mg serum does not
reflect dietary intake. Consistent with an earlier study (Weller et al., 1998) there were no differences in serum Mg between SU and NU.
Based on the described findings it should be questioned why young athletes use Mg supplements. The benefits of those supplements
seem to be lacking, while the risk of contaminated supplements should not be underestimated.
References
Braun H., Koehler K., Geyer H., Kleinert J., Mester J., Schaenzer W (2009). Int J Sp Nutr Exerc Met, 19(1), 97-109
Weller E., Bachert P., Meineck HM., Friedmann B., Bartsch P., Mairbaurl H (1998). Med Sci Sp Exc, 30(11), 1584-1591
Fogelholm M., Laakso L., Lehto J., Ruokonen I (1991). Nutrition Research 11, 1111-1118
Fogelholm M (1995). Int J Sp Nutr 5(4), 267-284
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ANNUAL CONGRESS OF THE EUROPEAN COLLEGE OF SPORT SCIENCE