Alcohol is considered by many to be detrimental to the health. Such a viewpoint is not unsubstantiated because alcohol, chemically called ethanol, is a metabolic poison. Alcohol is not essential to the health but is a source of calories, providing 7 kcals per gram. Once ingested alcohol can be oxidised as a source of energy by conversion to acetate and then acetyl-CoA, but in this process it is converted to an intermediate called acetaldehyde. This intermediate is highly toxic, and it must be quickly eliminated so that it does not cause damage to the cells of the liver, the location of detoxification. Large quantities of alcohol however cause the amount of acetaldehyde in the cells of the liver to increase and this can have a detrimental effect through the generation of free radicals that induce oxidative stress that can damage cell components. It is the increase in the systemic oxidative stress caused by alcohol that may produce the detrimental long term physiological effects of alcohol consumption.
However, while it is true that excessive alcohol intake may be a cause of oxidative stress and that this may cause metabolic disruption, increasingly it is being shown that moderate alcohol consumption is beneficial to the health. It has been shown for example that alcohol consumption is inversely associated with mortality, particularly mortality from cardiovascular disease. In studies investigating alcohol consumption in twins (to eliminate the genetic differences seen between normal individuals), it has been shown that higher than usual alcohol consumption is associated with a lower risk of cardiovascular deaths. In particular, red wine consumption is known to have cardioprotective effects in those that regularly consume moderate amounts of alcohol. This has lead to speculation that it is the antioxidant within the grapes that provide some of the cardioprotective effects to wine drinkers. This viewpoint is supported by research, and in particular the polyphenolic antioxidants do appear to provide cardioprotective effects.
So do the polyphenols in red wine, cider and other alcoholic drink made from fruit, explain the beneficial health effects of drinking alcohol? Evidence suggests that while they do provide some benefits, they cannot explain all of the health effect. It is now clear that it is the alcohol component of alcoholic drinks that is responsible for some of the cardioprotective effects of regular moderate alcohol consumption. Interestingly, alcohol in moderation also appears to have weight loss effects in humans. As body weight increases are associated with an increased risk of cardiovascular disease, this may be partly responsible for some of the cardioprotective effects of alcohol. However, alcohol also appears to have an very short term effect on the risk of myocardial infarction, such that for 24 hour following alcohol consumption, the risk of a suffering a heart attack decreases significantly. Alcohol therefore appears to have some interesting properties that may provide significant health benefits.
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