ABSTRACT
Chapter 2 examines the nature, types and usages of dietary and nutritional supplements (DNS) as PIEDS. DNS are not inherently unhealthy products in the same way that alcohol, soft drinks and fast foods may be considered unhealthy. However, concerns have been raised with respect to their efficacy, health risks and the risk of accidental doping. While the efficacy of supplements remains difficult to ascertain, meta-analyses of commonly sold supplements have generally come to the conclusion that while some are demonstrably efficacious, a large percentage of the market consists of products with little or no scientific backing. With respect to the health risks of DNS use, while acute adverse effects are uncommon, there are some indications that the use of supplements may result in negative health outcomes. Nevertheless, this is rare and usually associated with now prohibited substances in sport. Perhaps more significantly is the perception that DNS products are always safe to take, even in above recommended dosages. Another concern with respect to DNS is that they may contain prohibited substances. While not a concern for a majority of people taking DNS, it may be significant for elite-amateur or semi-professional athletes.
