Despite an ever increasing amount of evidence that a moderate consumption of alcohol has a beneficial effect on many aspects of health, the vast majority of work concerns the effect on coronary heart disease, and that easily defined indicator of general ill health, death.
What is coronary heart disease?
Coronary heart disease (CHD) is one of the main causes of death in the developed world. Generally vying for the position of number one killer with bronchial carcinoma (lung cancer caused by smoking), it is so prevalent because of the Western lifestyle - smoking (again), diet and sedentary behaviour, although family genetics also play a role.
With increasing age, atherosclerotic plaques form within the walls of the blood vessels. These plaques are already present in primary school age children. With time, plaques in the coronary arteries (three vessels that supply the heart with blood) may impede the blood supply to the heart muscle.
Heart muscle with an unsatisfactory blood supply may become ischaemic (starved of oxygen), particularly during exercise. This manifests as chest pain, known as angina. Should one or more coronary arteries become suddenly blocked, by rupture of one the plaques and the formation of blood clot in and around it, the blood supply to a part of the heart muscle is lost completely. This section of muscle then dies. This is a myocardial infarction, commonly referred to as a heart attack.
This whole spectrum of disease can be referred to as coronary heart disease or ischaemic heart disease.
Can alcohol help prevent this?
To be frank, the best way of reducing your risk of heart disease (and many other illnesses at the same time) is to stop smoking, eat a balanced diet and take some regular exercise.
There is, however, as mentioned above, a large amount of evidence that a regular intake of a moderate amount of alcohol can reduce the risk of dying. In truth, if you wish to reduce the risk of death from coronary heart disease alone, drinking large amounts would seem to achieve this. Many studies show that those with the lowest risk of CHD related death are those that drink the heaviest. It's a foolish course to take though, as these heavy drinkers suffer more deaths from liver disease, alcohol-related cancers and accidents, and overall they have a higher death rate than the general population.
Those with an overall lower rate of death seem to be the moderate drinkers, taking perhaps two units of alcohol per day. At this level of consumption, deaths related to CHD are reduced, but the deaths related to excessive alcohol consumption are not seen. This lowering of the death rate with moderate consumption, and climbing death rate with excessive consumption, is demonstrated best by the U-shaped or J-shaped curve.
Get specific
So what's the evidence? Research in this field is epidemiological in nature, meaning that it involves the study of populations, in our case trying to relate drinking patterns to disease patterns (see 'Study design: why it so difficult to 'prove' any of the theories about the beneficial effects of wine or other alcoholic drinks') Such research has been conducted for years, but there has been some compelling evidence produced in recent times.
The largest studies provide the best evidence. In 1997 Thun et al demonstrated a reduced risk of death from CHD with up to two drinks per day, but an increased death rate with more than three drinks per day. This study involved a staggering 490 000 adult Americans, and was adjusted for confounding variables.
In 1990 Boffetta et al published work demonstrating a decreased risk of death with up to two drinks per day, but no benefit from drinking any more. This involved 276 802 men aged 40 59, and was adjusted for age and smoking, but not for other confounding variables.
Gaziano et al, publishing in 2000, studied 89 299 US male physicians. Up to one drink per day conferred a lower overall mortality. There was no benefit from drinking more than two drinks per day.
In 1995 Stampfer published work involving 85 709 women aged 34 59. There was a lower risk of death in drinkers consuming 18 drinks per week (about 2.5 drinks per day). Drinking more than this resulted in an increased risk of death (from cancer and cirrhosis). This study was adjusted for confounders.
Doll studied 12 321 British doctors, publishing in 1994. The lowest risk of death occurred with one to two drinks per day. CHD deaths were reduced in all drinkers.
All these studies agree: reduced death with moderate consumption (up to two-to-three drinks per day), with no benefit and often increased risk of death with higher levels of consumption.
There are other supportive studies, which demonstrate lower rates of CHD related death with increasing levels of alcohol intake, but do not study overall death rate and are therefore not applicable in real life. These are Valmadrid (983 diabetics, 1999), Klatsky (128 934 Californians, 1997) and Rimm (51 529 male physicians, 1991).
Conclusion
Moderate drinking (up to about two drinks per day) reduces your risk of death, because it reduces your risk of CHD.
Drinking heavily reduces your risk of dying from CHD even further, but overall you are more likely to die because of increased risk of cancer, liver disease and trauma.
These findings do not represent a reason to take up drinking if you currently abstain, but they do represent a reason to cut back if you imbibe heavily.
If you are worried about your risk of heart disease (perhaps because of family history), don't smoke, take some exercise and eat a balanced diet. For advice about any of these, see your general practitioner.
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