[Frequency of Worsening Clinical Test Values Related to Supplement Use: Estimation by Using Nationwide Online Survey]

This study examined the frequency of worsening clinical test values related to supplement use using a nationwide online survey, with a focus on liver function markers, and clarified the differences between outcome indices of diarrhea or skin manifestations. A nationwide online survey was conducted with 73,010 supplement users from the previous year. Of these, 221 individuals with worsening clinical test values responded to the full-scale survey. To compare surveys with different outcome indices, we used previously reported data from similar surveys.Only 0.5% of individuals who self-reported worsening of clinical test values caused by supplement use recognized an almost certain causal relationship. Among the test items, blood lipids were the most frequently reported. The frequency of worsening liver function markers was 0.2% in supplement users. Among those who experienced worsening clinical test values, 56.1% received no treatment and 82.4% did not report the incidence of worsening clinical test values anywhere. The ingredient-based classification of products revealed more "Peptides or animal by-products" and "Combination products/not classifiable products" than those associated with other categories. Compared to the results of the survey about the experience of diarrhea or skin manifestations, those who experienced worsening clinical test values were predominantly men, frequent and long-term users, and individuals whose products could not be identified.Few supplement users experience worsening of liver function markers, which does not seem serious. However, it is difficult for supplement users to recognize abnormal changes by themselves. Thus, it is important to record product information, usage, and changes in physical condition.