en عمومى General مروری Review <strong>Introduction: </strong>Dietary supplements (DS) are&nbsp; preparations&nbsp; intended&nbsp; to deliver nutrients&nbsp; that&nbsp; may not &lrm;be consumed in sufficient quantities in the diet. They improve health&nbsp; and are popular in different &lrm;populations and age groups. Nevertheless, this popularity and most of the time using them&nbsp;&nbsp; without &lrm;health professional advice expose consumers to the ingestion of different harmful contaminants that &lrm;may lead to deleterious effects on human health. &lrm;<br> <strong>Methods: </strong>A comprehensive literature search was performed during years 1994-2020. Many medical and &lrm;scientific literatures on the authors opinion regarding presence of metal contaminants in DS and the &lrm;analytical methods were collected.&nbsp;&nbsp;<br> <strong>Results: </strong>In different categories of DS metal contamination might occur as a consequence of a single &lrm;factor or as a combination of sources. For determination purposes many analytical techniques have been &lrm;developed. However, selection of a technique&nbsp;&nbsp;&nbsp; depends on the elements, concentration in the digested &lrm;sample, detection limits, interference, accuracy, precision, linear range, and etc. &lrm;<br> <strong>Conclusion: </strong>Various authors emphasized&nbsp; on applying&nbsp; proper&nbsp; quality control&nbsp;&nbsp;&nbsp; in different &lrm;steps of dietary supplements production and&nbsp; quality assurance&nbsp; of all manufacturing phases&nbsp; to &lrm;ensures that packaging materials and final products conform to&nbsp; the established criteria&rsquo;s of the &lrm;country.&nbsp; It is&nbsp; hoped&nbsp;&nbsp; besides proper&nbsp; quality control and use of&nbsp;&nbsp;&nbsp; reference materials&nbsp;&nbsp; as a critical&nbsp; &lrm;step , the&nbsp;&nbsp; knowledge of consumers&nbsp; toward the use of DS&nbsp; be increased by&nbsp; holding&nbsp; health care &lrm;communication&nbsp; programs and&nbsp; these products&nbsp; consumed under medical advice.&lrm; Dietary supplements, Contaminants, Accuracy, Precision, Quality Assurance, ‎Reference Material 11 17 http://intjmi.com/browse.php?a_code=A-10-1-352&slc_lang=en&sid=1 Mehri Aliasgharpour 10031947532846004290 10031947532846004290 Yes Member of Biochemistry Laboratory Faculty, Reference Health ‎Laboratory, Iran Ministry of Health & Medical Education, Tehran, Iran