NOT THAT THE LACTOSE INTOLERANCE IS REAL TO BEGIN WITH:

In a curious study, a team of Italian gastroenterologists asked people with and without diagnosed lactose intolerance to take lactose for an experiment on its effects on bowel symptoms. But in reality the participants received glucose, which does not harm the gut. Nonetheless, 44 percent of people with known lactose intolerance and 26 percent of those without lactose intolerance complained of gastrointestinal symptoms.

In one remarkable case, a participant in an antidepressant drug trial was given placebo tablets -- and then swallowed 26 of them in a suicide attempt. Even though the tablets were harmless, the participant's blood pressure dropped perilously low.

The nocebo effect can be observed even when people take real, non-placebo drugs. When medical professionals inform patients of possible side effects, the risk of experiencing those side effects can increase. In one trial, the drug finasteride was administered to men to relieve symptoms of prostate enlargement. Half of the patients were told that the drug could cause erectile dysfunction, while the other half were not informed of this possible side effect. In the informed group, 44 percent of the participants reported that they experienced erectile dysfunction; in the uninformed group, that figure was only 15 percent.

In a similar experiment, a group of German psychologists took patients with chronic lower back pain and divided them into two groups for a leg flexion test. One group was told that the test could lead to a slight increase in pain, while the other group was told that the test had no effect on pain level. The first group reported stronger pain and performed fewer leg flexions than the second group did.

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