intake of athletes was 77% of the RDA. However,
vitamin E deficiencies are rare in athletes with
a well-balanced diet. Although megadoses of
vitamin E are relatively harmless, some individ-
uals experience gastric disturbances and weak-
ness when taking supplements ranging from 200
to 1000 IU (Clarkson 1991). Acute exercise has
been shown to result in an increase of plasma
levels of tocopherol, and the author suggested
that tocopherol was mobilized from adipose
tissue into the blood to be distributed to exercis-
ing muscles; however, this study did not correct
for haemoconcentration and the small increase in
plasma tocopherol was back to baseline after
10 min rest (Pincemail et al. 1988). This response
to exercise has not been reported in another
study (Duthie et al. 1990). It is not clear if the dis-
parate findings are due to different exercise
loads, different testing methods or to other
factors.
Many studies have reported a significant effect
of vitamin E supplementation on exercise perfor-
mance, but the actual benefits are doubtful since
many of these experiments were not well con-
trolled. Those studies that have been well con-
trolled have generally shown that vitamin E
supplementation has no effect on performance
(Shephard et al. 1974; Watt et al. 1974; Lawrence
et al. 1975). On the contrary, supplements of
vitamin E showed a beneficial effect on
maximum oxygen uptake and a partially protec-
tive effect on cell membranes at high altitude; it
was reported that mountain climbers with a
vitamin E supplement working at an altitude of
5000 m exhaled lower levels of pentane, a marker
of lipid peroxidation, and exhibited a higher
anaerobic threshold than controls (Simon-
Schnass & Pabst 1990). Another study also
showed that the impairment of blood flow
parameters was attenuated by vitamin E
supplementation in mountaineers at altitude
(Simon-Schnass & Korniszewski 1990). The posi-
tive effect may be due to the antioxidant proper-
ties of vitamin E. At high altitudes, vitamin E
may counteract the effect of the increased lipid
peroxidation of red blood cell membranes
caused by the decreased availability of oxygen
(Williams 1989). Vitamin E may also play a role in
reducing muscle damage and oxidative stress, as
shown by a reduction in muscle-specific enzyme
levels in serum after strenuous exercise (Rokitzki
et al.1994b). However, results are equivocal as to
whether muscle damage can be reduced by
vitamin E supplementation (see Chapter 20).
In short, there has been much debate on the
vitamin requirements of athletes, yet carefully
controlled studies are limited.Conclusion
The following is a summary of the main
viewpoints.
1 Vitamin deficiencies may result in decreased
exercise performance, and it has been demon-
strated that vitamin supplements improve per-
formance in persons with pre-existing vitamin
deficiencies.
2 Vitamin supplements are generally unneces-
sary in athletes consuming well-balanced diets.
3 Athletes participating in strenuous training
may need monitoring of vitamin status even if
consuming the RDA levels of vitamins.
4 Vitamin supplements should be suggested for
athletes in special conditions including those
who are on a weight loss diet, or have eating dis-
orders, or low energy intakes. Supplementation
is only warranted when there is reasonable
evidence to suggest that a deficiency may be
present.
5 Excessive vitamin intake, especially of the fat-
soluble vitamins, can be accumulated to a level
that may be toxic. Prolonged excessive intake of
water-soluble vitamins also may be harmful and
cause nutritional imbalances. Attention to food
choices, rather than specific supplementation, is
the preferred option.References
Armstrong, L.E. & Maresh, C.M. (1996) Vitamin and
mineral supplements as nutritional aids to exercise
performance and health. Nutrition Reviews 54 , S149–
S158.
Aroson, V. (1986) Vitamins and minerals as ergogenic
aids.Physician and Sports Medicine 14 , 209–212.