They're both real, but what matters is the net effect: the J-curve. People who drink about a standard drink per day are about 14% less likely to die than are never-drinking teetotallers,* and the benefits of moderate consumption wash out by the time you're consuming about 3-4 standard drinks per day. And the risks mount from there.
Another study is out on the cardiovascular benefits of moderate drinking. There are some oddities in there, like finding differences across different types of alcohol. Rimm & Moats' 2007 study remains the most convincing: they restrict things to a sample of healthy adults with few potential unobserved confounds and find that moderate drinkers' relative risk of chronic heart disease was 0.38. Drinkers' chances of getting chronic heart disease are less than half of abstainers' risk. They conclude:
The evidence discussed above provides substantial support for the hypothesis that moderate drinking reduces the risk of CHD. Beer, wine, and spirits all have demonstrated significant benefits. These benefits are likely mediated through strong and lasting effects of alcohol on HDL cholesterol, fibrinogen, and glycemic control. The ‘‘sick-quitter’’ hypothesis and the concern that moderate drinkers lead a healthier lifestyle may explain a small proportion of the benefit attributed to alcohol in some studies, but recent studies which have removed sick quitters, updated alcohol and covariate information on diet and lifestyle factors, and separately documented benefits of alcohol among healthy and unhealthy populations further add to the evidence that moderate alcohol consumption is causally related to a lower risk of CHD.So it is interesting that the New Zealand Heart Foundation's Heart Age Forecast Tool doesn't ask about your alcohol consumption. If you can cut your risk of chronic heart disease by more than half by drinking moderately, shouldn't that be in the Forecast Tool? The Heart Foundation tries to downplay the effects of moderate alcohol consumption on CHD, saying that the benefits don't hold for everyone. But if most of the benefits come from drinking in middle age, and the forecast tool asks your age...
* Update: the relative mortality risk of moderate drinkers as compared to never drinkers is 0.86. So whatever your risk of dying if you're a non-drinker, moderate drinkers' risk is 86% of that.