https://www.vice.com/en_us/article/g5vyxb/white-people-who-got-placebo-from-white-doctors-felt-better-study-says

In 1807, Thomas Jefferson wrote that one of the best doctors he knew was more likely to use “bread pills, drops of colored water, and powders of hickory ashes” than other medicines —and with equal success in healing people’s ailments.

Jefferson called these interventions “pious frauds”; today we call them placebos, or inert substances that can nevertheless make people feel better when they are unwell. But the placebo effect goes far beyond just sugar pills, or today’s equivalent to hickory ashes. We know now that the entire context around a medical encounter is rife with influences that can impact how a person responds to treatment, in combination with their expectations and beliefs. A recent study in PNAS sought to explore one of these contextual elements: how the race or gender of a provider might influence the placebo effect.