Many clinical trials fail to measure micronutrient levels before and after treatment, potentially leading to inaccurate conclusions about supplement efficacy.

“several of the studies included in this me metaanalysis did not measure the concentration of vitamins and minerals in individuals in the study at Baseline or followup therefore any negative data is difficult to interpret and no conclusions should be made because it's impossible to know whether or not the dosing was adequate of vitamins and minerals and or whether or not people were compliant”