The best evidence for efficacy from adequately designed randomized controlled trials (RCTs) is available for Coccinia indica and American ginseng. Chromium has been the most widely studied supplement. Other supplements with positive preliminary results in
M. Warr, and P. Mishra. Society for Information Technology & Teacher Education International Conference, page 1011-1018. Association for the Advancement of Computing in Education (AACE), (2019)