Why do medical recommendations constantly change?

At least monthly it seems like there is “new research” or “new guidelines” that are published and tell the reader that what was previously thought is now considered wrong.  Butter is bad, but margarine is better--5 years later, no, margarine is bad, butter might be better.   Or, running is better than walking, wait no, walking is usually better than running This flip-flopping can make decisions annoying at best and impossible at worst; I know it drives my mom nuts.  However, I think this flip-flopping is just the nature of research and goes along with living an evidence-based life. Here are some reasons that I believe contribute to this flip-flopping.

A big part of having an “evidence-based” attitude is making the best possible decision for a given situation using the best available evidence.  When considering why it’s ok that recommendations change, it’s important to remember that decisions (and thus recommendations) are based on what’s available at that particular time.  Because of this, as new research becomes available, the recommendations ought to change to reflect new knowledge.

Even if there is no new research available, another reason for recommendations to change is if the originally available research has been reexamined and has been found lacking.  No human is infallible, and scientists certainly aren’t excluded from this characteristic! There could be statistical mistakes, or even underlying study design mistakes that could significantly change a border-line conclusion.

One more reason for the apparent flip-flop nature that I’d like to highlight is the news media and their love of sensationalism.  It’s much more exciting to say something like, “sunscreen causes Rickets,” than “preliminary research suggests a correlation between prolonged sunscreen use and vitamin D deficiencies” (fictional example).  Obviously, if I were trying to attract attention I would chose the first headline, but as a consumer I should realize that the news article probably doesn’t give me the whole picture.

Despite these difficulties in having an “evidence-based” approach to life, I truly think it is worth the extra effort to think through decisions, and then to periodically rethink the same decisions, even if that means changing your position.  It has taken me years to realize that it’s not a bad thing to change my mind, sometimes there’s new information available, or sometimes the situation could have changed.  And sometimes, I hate to admit it, just sometimes, I was actually wrong in the first place.