The placebo effect --belief in this or that or the other--- occurs as much as 10% of the time in some lab experiments. First read this some 20 years ago.
Here is utube and much newer version of placebo-nocebo effects in three differrent kinds of lab experiments. One of the experiments is title ' Mind Over Milkshakes '..
Of course there is also Dr. Bruce Liptons Power of Belief books and vids also from 20 or so years ago. Also amzing stuff from someone who knows his stuff very well.
My mother {moderate to heavy drinker and ciggerette smoking } attempted to be Christian Scientist { Mary Baker Eddy } --that religion pretty much died out--- and their thing was about ' Mind Over Matter '.