Final answer:
Dietary supplements do not undergo the rigorous testing that prescription medications do before being marketed. They are regulated by the FDA more similarly to food, and manufacturers are allowed to make certain health claims without FDA approval. Supplements have been associated with health risks, including undisclosed harmful substances, and should complement, not replace, a balanced diet.
Step-by-step explanation:
The statement that unlike prescription medications, dietary supplements are not rigorously tested, refers to the regulatory practices of the Food and Drug Administration (FDA). While prescription medications undergo extensive safety and efficacy testing before they can be marketed, dietary supplements are regulated more like food items. Supplements must adhere to Good Manufacturing Practices, but they do not face the same pre-market testing and approval that medications do. Moreover, manufacturers can make certain health claims about their supplements, although these claims do not undergo FDA approval and must be accompanied by a disclaimer. This means that there can be a significant risk associated with supplement use, including potential health problems such as toxicity or contamination, which may not be discovered until after the product has been in widespread use.
Recent studies and reports have highlighted concerns over supplements, including the presence of harmful substances in some 'natural' products, like undisclosed amphetamine-like compounds or liver-damaging ingredients. Even some protein powders, popular among bodybuilders, have been found to contain unsafe levels of heavy metals or to engage in 'protein spiking', according to investigations from groups like Consumer Reports. There is also evidence of widespread mislabeling and incorrect health claims in the industry. Ultimately, food itself is the best source of nutrients, and any supplements taken should be seen as an addition to, not a replacement for, a balanced diet.