MD, PhD, FMedSci, FSB, FRCP, FRCPEd

Athletes tend to adopt a healthy life-style, and today this seems to include the regular intake of a range of dietary supplements. Supplements specifically marketed for sports-people promote good health and performance, we are constantly told – but is this true?

A 2010 review found that “there is good evidence that caffeine can improve single-sprint performance, while caffeine, creatine and sodium bicarbonate ingestion have all been demonstrated to improve multiple-sprint performance. The evidence is not so strong for the performance-enhancing benefits of β-alanine or colostrum. Current evidence does not support the ingestion of ribose, branched-chain amino acids or β-hydroxy-β-methylbutyrate, especially in well trained athletes.”

However, a 2011 paper was considerably more cautious: “For most supplements, the evidence is weak, or even completely absent. A few supplements, including caffeine, creatine, and bicarbonate, are supported by a strong research base. Difficulties arise when new evidence appears to support novel supplements: in recent years, β-alanine has become popular, and the use of nitrate and arginine is growing. Athletes seldom wait until there is convincing evidence of efficacy or of safety, but caution is necessary to minimize risk.”

The purpose of this new article was to collect the most recent data regarding the safety of well-known or emerging dietary supplements used by athletes.

The review suggests that about 90% of sports supplements contain estrogenic endocrine disruptors, and about 25% of them having a higher estrogenic activity than acceptable. About 50% of the supplements are contaminated by melamine, a source of non-protein nitrogen. Additional data accumulate toward the safety of nitrate ingestion. In the last 2 years, the safety of emerging supplements such as higenamine, potentially interesting to lose weight, creatine nitrate and guanidinoacetic acid has been evaluated but still needs further investigation.

The authors of this article claim that “the consumption of over-the-counter supplements is very popular in athletes. Although most supplements may be considered as safe when taking at the recommended doses, athletes should be aware of the potential risks linked to the consumption of supplements. In addition to the risks linked to overdosage and cross-effects when combining different supplements at the same time, inadvertent or deliberate contamination with stimulants, estrogenic compounds, diuretics or anabolic agents may occur.”

Despite these cautions, the market for supplements is growing and the myth that supplements are good for health continues. The truth is, however, more complex and far less encouraging:

  • It is impossible to generalise across the entire range of highly diverse supplements.
  • Some have positive effects.
  • The vast majority do nothing at all.
  • Most are quite harmless.
  • Some can have serious adverse effects.
  • All of them cause harm to your bank account.

3 Responses to Dietary supplements are good for athletes – aren’t they?

  • I stumbled across this website while searching for something else. The A–Z list of supplements is pretty horrifying. It goes far further than the problem indicated by your post and overlaps into areas of CAM/herbalism. Among the outstanding pieces of lunacy are HCl (yes, hydrochloric acid – they spell it HCL), which is sold in tablet form! And there’s Green Tea, described as ‘fat loss in a cup’.

    Gyms sell dietary components (e.g. carbohydrates and proteins, not supplements) in huge buckets. I feel for the poor victims who believe that, in order to keep fit, they have to ingest all sorts of goo in vast quantities.

  • Time will tell if nearly 50% of imported sports supplements contaminated with melamine in South Africa extends to other countries. My best guess is that either the supplements were manufactured in China or at least one of the ingredients originated from that country.

  • Or in the case of AFL football teams, a lot of heartache.

    https://en.wikipedia.org/wiki/Essendon_Football_Club_supplements_saga

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