Lamport, Lawton, Merat … Dye. American Journal of Clinical Nutrition. 103: 775-783.
The intent of this study, funded by Welch Foods, was to show that grape juice improves driving ability in stressed people (moms of teens). The authors concluded that the flavonoid-rich grape juice has cognitive benefits.
No baseline test of their driving after drinking plain water was performed.
Note: The “placebo” drink ingredients were not specified. I contacted the researchers and was told that it was supplied by Welch, wasn’t Kool-Aid, and looked/tasted like grape juice but ingredients were unknown. One can only assume it must have contained artificial coloring and flavoring.
Note: Having no baseline, and having a possibly “active” placebo containing artificial dyes and flavors means it is not really known if the grape juice made the moms drive better … or if the artificially-colored/flavored “placebo” made them drive worse.