One of my favorite sayings is that “the plural of anecdote is not evidence.” This means that success stories alone about a treatment or therapy are not proof that it is likely to work. What makes a treatment “controversial” is that there is lots of public dispute or debate (and conflicting opinions) about whether the treatment will prevent, cure or treat some condition.
Every day, we see advertising that asks us to try certain products. The ads promise to help us lose weight, build strength, grow hair and address all sorts of health problems. We also see marketing that wants us to “train our brains” in ways that make us read faster, remember more, think faster, and be more relaxed and better organized.
These types of products and services may not do any harm. But they often lack the independent research needed to say confidently that they work. These products have not been subject to well-controlled studies that have been replicated by other scientists. This is what makes them “controversial.”