It takes belief to have a placebo or nocebo effect.

Our beliefs can make us more or less likely to believe something else. Long-term familiarity with a doctor may make a patient more likely to have a stronger placebo reaction due to that previous trust relationship. A doctor might also have pre-conceived bias towards or against a treatment. When a bias of knowledge exists then it also may take more evidence to change the person's opinion.

See for more information: Bayes and Belief How pre-review belief influences critical appraisal. St. Emlyns.

https://www.stemlynsblog.org/bayes-and-belief-how-pre-review-belief-influences-critical-appraisal-st-emlyns/

Citrus peel - health food or healthy cleanser, or possibly both?

Disclaimer: Information shared for educational purposes within the guidelines of Fair Use.