These flips seem to happen on a cycle of 20 or 30 years. I don't think it's a coincidence that this is roughly the generational cycle. My theory is that each new generation of researchers establishes itself by overturning the findings of the previous generation—especially the shakiest ones.
No, I disagree that these flips are just moody periodic “flips of a coin”. The target article explains very clearly WHY the flip. Here are the three main reasons:
1. An ascertainment bias that is built in to studies that recruit and compare “non-drinkers” to light drinkers. Non-drinkers may not be as inherently healthy as light drinkers. They may have had adverse effects earlier in their lives due to alcohol.
2. Since the 1970s most of NIH research has focused on alcoholism and alcohol abuse—-not on the epidemiologucal impact of drinking alcohol. These are entire distinct topics. Alcoholism is treated as a “disease” in the same way as other addictions. But a significant majority of drinkers are not alcoholics, and what is the impact on mortality of alcohol use on all types of age related diseases.
3. There was a long-term phantasy that resveratrol in red wine is responsible for the French paradox metabolic benefits. That gas been debunked for a decade but still lives in our brains as a zombie meme.
Reminds me of Planck's principle:
> A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die and a new generation grows up that is familiar with it ...
I think a lot of it is just garbage science by people who were paid by some industry to come up with anything that could result in a snappy headline that might boost sales of their product, combined with media being perfectly happy to misrepresent even honest research if they can get a clickbait title out of it. "Science says Bad Thing you like is actually good for you!" is about as sure to generate clicks/views/ad impressions as "Science says Healthy Thing is actually killing you!"
With near zero accountability for bad science and journalism this situation isn't likely to change any time soon.