Flaws Found in Moderate Drinking Studies
In reviewing past studies that seemed to indicate that moderate drinking had some health benefits, researchers found that former drinkers were being included in the categories of "abstainers" or "occasional drinkers." The problem is doesn't factor in why the former drinkers stopped drinking. It could very likely be that health issues were behind the lifestyle change. In these same studies, if former drinkers are removed the apparent health benefits of moderate drinking disappear.
The researchers believe that isn't the moderate, occasional drinking that gives health benefits but something else that these same people are doing, such possibilities as exercising or healthier eating.
Another indication of flaws is found in the list of what moderate drinking supposedly reduces: "deafness, hip fractures, the common cold, cancers, birth compilications, dementia, and even liver cirrhosis." Lists like these don't make sense from a physiological view because there is no common point that alcohol could impact and some, like liver cirrhosis is known to be aggrievated by alcohol usage.
[Alice Walton, "Moderate Drinking May Not be as Healthy as We Thought," Forbes, 2016-03-23]