I think the concern is that there are many studies that all contradict each other. I've read about how wine is good for the heart, while others show that any amount of alcohol leads to negative health effects. Maybe both are right because they measured very specific effects.

People get tired of public health recommendations constantly flip-flopping (health effects of butter is another).

The human body is incredibly complex, and most studies look at incredibly specific effects. "increases lifespan by x years" takes decades to measure, but "increases blood cholesterol by x" can be measured much faster. So in the interest of getting papers published in reasonable timeframes most studies take the latter approach.

Then comes media, sees "X causes blood cholesterol to rise, cholesterol is bad, so X is bad" which is a deeply flawed conclusion. Most things aren't universally bad (high blood pressure is bad, but if you raise your blood pressure through exercise that actually lowers blood pressure in the long run), and many negative effects are offset by positive effects not looked at in the study. I wouldn't read too much into anything that isn't a metastudy and took less than a decade to test.

I think the current consensus about red whine is somewhere along the lines of: red whine is good for you, the more you drink the more that effect is offset by negative effects of alcohol, but in the amounts that were always recommended (about 1 glass a day) it's not a huge factor.

But of course those are the harmless examples, there's also interference from industry groups interacting with the current publishing environment (see the whole "fat is bad for you" that we had going for decades for no good reason). So there is a lot of room of improvement.

Studies on alcohol can show better results for moderate users because people who don't drink may have other medical issues or problems related to alcohol.

It's such a big part of culture that people who never drink often have a specific reason not to.

The most common specific reason for someone not to drink is religious. Religions with alcohol restrictions tend to also have other restrictions (both lifestyle and diet) that confound things. Thus it is really hard to know if any difference is from alcohol restriction or from something else.

Another reason people abstain from drink is because they used to drink heavily until it caused noticeable harm. If some of that damage is permanent, it can make moderate alcohol use seem comparatively healthy even if it's also slightly harmful.

The control group is obviously people who do not drink, period -- they don't say drinking moderately is better compared to someone who doesn't drink because they already have alcohol related issues.

No, that's not an obvious or safe assumption at all, and in fact I believe this is from the study that inspired the article linked in the root comment:

> The lack of objective confirmation of actual amount of alcohol consumed, lack of information concerning alcohol intake before baseline, and inclusion of ex-drinkers with never drinkers in the non-drinker category, as well as lack of assessment of drinking patterns place reservations on the observed findings.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3377489/

I think the moderate is the more sighworthy part because in that context it is a tautology if it is an ammount that causes problems it isn't moderate by definition.

That and those sorts of food studies tend to be bullshit marketing pushes to drive consumption in the first place.