Vitamin And Mineral Use By Athletes

The use of vitamins and minerals as ergogenic substances has been reviewed recently by Sobal and Marquart (355). They analysed 51 studies that provided data on the quantitative use of such preparations in over 10000 male and female athletes. The mean prevalence of use was 46%. Elite athletes used more supplements than lower ranked athletes, and women used more than men. Of the 51 studies, 32 provided information about the type of supplement used. Multivitamins and iron were most frequently taken, followed by B vitamins, vitamin E, calcium and vitamin A. Women athletes particularly took iron, sometimes in high amounts. In most cases, iron supplements were used on a regular daily basis, rather than occasionally or weekly.

Some studies found that some elite athletes exhibit extreme levels of supplement use. Some Olympic athletes were found to consume as many as 14 different types of supplements/day and 63 pills/day (355). Faber and Spinnlerbenade (352) described an average supplement pill intake of 19 per day, with one athlete consuming as many as 87 pills per day.

Reasons for supplement use were various: performance enhancement; providing extra energy; illness prevention; vitality enhancement; insurance to get a daily adequate intake of important vitamins and minerals; support of training adaptations; and muscle development.

Information on why specific supplements are used is most frequently obtained through coaches although parents, doctors and peers also are important. A survey by Parr et al. (357) revealed that the opinion among athletes, coaches and trainers in the US is that the trainer is expected to have the primary responsibility for the athlete's nutrition.

Media and industrial advertising have great influence on decision making (353, 354). The myth that vitamins will give extra energy, as is often claimed in advertising, is misleading, but is accepted by part of the athletic population who are persuaded to take extra vitamins when muscle weakness or fatigue is present (351).

The myth that l-carnitine enhances fat oxidation is plausible enough to persuade many endurance athletes as well as people willing to slim and reduce their body fat to use this supplement (368). A number of studies have analysed the nutritional knowledge of athletes and their trainers (350, 351, 353, 354, 356, 357, 359-361). These studies tend to show that a better level of information about aspects of daily nutrition and about efficiency of food supplements leads to a more reasonable ingestion of supplements.

Basic knowledge about the type of sport in which the athlete is involved and the consequences that this has for food consumption is considered to be important. Many endurance athletes, for example, do not realize that they ingest substantially more food, on a daily basis, than non-endurance athletes. The consequences of this larger food consumption are also an increased consumption of most micronutrients and of proteins. In this respect we had observed the opinion among coaches involved in professional cycling that the cyclists need extra protein to be able to complete the Tour de France. However, although this is factually right, it was observed that at the high level of food intake in these athletes and a constant level of approximately 12 en% protein intake, the daily protein intake level of 2.4 g/kg bodyweight was in excess of the enhanced requirements (165).

These examples show that proper, science based information is essential for the understanding of the interrelation between sport events and nutritional needs, especially at the level of decision making/of opinion makers such as coaches, trainers and parents.

Key points

  • Vitamins are essential cofactors in many enzymatic reactions involved in energy production and in protein metabolism.
  • Any shortage of a vitamin may lead to suboptimal metabolism, which in the long term may result in decreased performance or even illness.
  • Some vitamins act as antioxidants and there is accumulating evidence that nutritional antioxidants may help optimize the protective role for the maintenance of tissue/cell integrity.
  • Vitamin supplementation has been shown to restore performance capacity in cases of a vitamin deficit and to reduce tissue damage due to free radical production.
  • Vitamin supplementation with quantities exceeding those needed for optimal/blood levels has not been shown to improve performance.
  • As is the case for minerals and trace elements, athletes involved in intensive training, but consuming low energetic diets, are most prone to marginal vitamin intakes.
  • It can be concluded that vitamin restoration of energy dense processed foods or supplementation with preparations will not enhance performance but may, in athletic populations, contribute to adequate daily intakes.
  • Daily intake of a low dose vitamin or combined vitamin-mineral-trace element preparation, supplying the recommended safe daily intake, may be advised in periods of intensive training or in any situation where athletes have to abstain from a normal diet.
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