How much is too much? A case report of nutritional supplement use of a high-performance athlete

Journal Title (Medline/Pubmed accepted abbreviation): Br. J. Nutr.
Year: 2011
Volume: 105
Page numbers:1724-1728
doi: 10.1017/S0007114510005556

Summary of background and research design

Background: According to surveys, more than half of competitive athletes take some form of dietary supplements. If an athlete takes multiple supplements, it is possible for him or her to take more than the tolerable upper level of intake (UL) the amount described by the European Scientific Committee on Food as presenting an increased risk of adverse health effects when exceeded on a regular basis. Other countries/regions have their own recommendations and limits, which are generally pretty similar.

Research goal: To assess the dietary supplement usage of one athlete and to discuss the potential benefits and dangers of widespread supplement use.

Subject:One 19 yr old male competitive swimmer

Experimental design:case study

Protocol:The athlete’s diet and supplement use were analyzed for 3 days- 2 week days and one weekend day. A blood sample was analyzed for a multitude of nutrient levels and biochemical parameters.
Summary of research findings
  • The athlete habitually took 10 total dietary supplements including vitamins, minerals, creatine, a yeast extract, antioxidants, and coenzyme Q.
  • Diet alone could account for all of the macro- and micronutrients that he needed, except for vitamin D.
  • The athlete consumed 3 nutrients at levels that were above the European Scientific Committee on Food UL.
  • The daily supplement dosage was considerably above the maximum permitted level (MPL, as established by the German Institute for Risk Assessment) for 9 nutrients.
  • No actual health problems were reported in the athlete, but it is not known if long term intakes at these levels could result in eventual development of adverse health effects .

Key practice applications

Vitamin and mineral deficiencies are emphasized in our society, and supplementation is widely used.  It is important for people who take supplements to be aware of every compound that is in their supplements, and to compare labels of every supplement they are taking to avoid excess consumption.  It is also important for athletes to be educated on the risk of toxicity of any compound.  Supplementation is often recommended to improve health and sports performance if the athlete is deficient in a certain nutrient, but few data have suggested benefits in athletes that are in good nutritional status.  Athletes should focus on healthful diets that inherently include vitamins and minerals; these foods will also contribute healthful fiber, phytochemicals, and other benefits that supplements cannot offer.


  • Only one athlete was represented in this study, so he of course does not represent all athletes.
  • Due to high energy expenditure, athletes require more calories than non-athletes.  The article did not mention if the “upper level” guidelines are similarly applicable to athletes as they are to the general population.  For example, are athletes’ micronutrient demands higher that the recommendation?  Are there particular micronutrients that athletes should focus on?
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