Perspective
Matthew F. Muldoon
Matthew F. Muldoon
This study adds information about whether alcohol might be protective in smaller amounts. The study found that it was not.
The researchers did the study in China for a reason. There is a particular research strategy that they had using certain genetic polymorphisms that predict alcohol intake that are more robust in Chinese people. It nonetheless speaks generally to the effect of alcohol and CVD.
This study is not without significant limitations. At the end of the day, it is an observational study. It is not a clinical trial and it is only through experimental studies such as a clinical trial that we can really show cause and effect. This study employs a newer technique, Mendelian randomization, to improve upon our ability in observational studies to demonstrate cause and effect. It is a step forward in terms of methodologies for observational studies.
Nonetheless, this study was rigorously done and the findings are important. They are probably as important in China as they are around the world.
We have long thought that alcohol is protective at low levels, but we have always known that it is detrimental at high levels for CVD. Whether this protective effect in low amounts has not been proven. The suspicion has been based upon observational studies. It is not as if we have trials that show that low amounts of alcohol are protective. This “new and improved” observational study does not find a protective effect in low amounts. That is important.
Clinicians, by and large, do not encourage alcohol intake. What we often do is when we encounter someone with moderate intake, we say, "That is fine." We sometimes go so far as to say that what the patient is doing might be good. This study casts some doubt upon us continuing that last statement. The new study did not find that low amounts are bad (one drink per day for women and two drinks per day for men). Certainly, once you get beyond that, it is clearly bad no matter how you look at the data.
We may need to back away from saying or implying that mild consumption is a good idea and simply say that alcohol in excess is bad, rather than sometimes give some implicit encouragement to continue two drinks per day. The public has heard that message, but we have never known it to be a valid recommendation.
There is another subtlety in this study related to the fact that it was done in China. Asians have a lot more stroke than heart disease, and they have a lot more hemorrhagic stroke than ischemic stroke. These data show that high amounts of alcohol are particularly bad for stroke, yet not related much at all to heart disease. In the United States, we are burdened more so by ischemic heart disease. So that does affect the applicability of this study to Americans. The researchers found that alcohol was most strongly associated with hemorrhagic stroke, which is not as prominent of an issue here as it is in China.
  • Matthew F. Muldoon, MD, MPH
  • Professor of Medicine
    University of Pittsburgh
Disclosures: Muldoon reports no relevant financial disclosures.