We’d all like to think that a small tipple – a glass of wine or a pint of beer, say – is not going to be bad for us, particularly at this time of year. So how much more are we likely to pounce on reports that such moderate amounts of alcohol might actually have some beneficial effects, like lower risk of heart disease?
There are a large number of such reports around to seize on. This week, The Telegraph light-heartedly covered a small study that suggested compounds present in champagne could have benefits for the heart, although further reading suggests this is still very much a hypothesis rather than a demonstration of a real effect on heart disease. Similarly, it’s worth reading this to judge a recent large-scale Spanish survey of the effects of really quite large amounts of alcohol on the heart.
So how do we make sense of all of this? Not least because when alcohol consumption spills over into heavy drinking, we know very well that it becomes a very serious and costly public health problem not just for individuals but also wider society.
OxSciBlog turned to Dr Naomi Allen of the Cancer Epidemiology Unit [CEU] at the University of Oxford. Naomi led research into the effects of drinking alcohol on rates of cancer as part of the Million Women Study.
OxSciBlog: What do we know about how light-to-moderate amounts of alcohol can affect health?
Naomi Allen: Everyone knows that heavy drinking is bad for our health, but what about the health effects of more moderate amounts of alcohol that most of us drink? Indeed, people who drink one or two drinks every day appear to have the lowest death rates (ie they live longer) compared with people who don’t drink at all and people who drink more heavily.
This is largely because moderate alcohol drinking has been shown to reduce the risk of heart disease in middle to late age.
However, moderate drinking (one to two alcoholic drinks each day) also increases the risk of developing certain types of cancer, especially breast cancer in women, but also cancers that were previously only thought to be related to heavy drinking, such as cancer of the liver, rectum and in smokers, cancers of the mouth and throat.
Most of this increased risk is for breast cancer, so the potential risks of moderate drinking are perhaps of most relevance for women. In particular, the risks may be of greatest concern for middle-aged women, whose risk of developing breast cancer is much higher than the risk of heart disease. For women over the age of 75, the risk of heart disease increases and the risks and benefits of moderate drinking are not so clear.
OSB: Why might alcohol be beneficial?
NA: Alcohol is believed to protect against heart disease in several ways, the most important of which is through increasing the amount of ‘good’ cholesterol in the blood (called high-density lipoprotein) that helps prevent blocked arteries, and also through reducing the ‘stickiness’ of the blood.
There has been much speculation that red wine may be most beneficial (due to the high content of compounds called polyphenols contained in some red grapes), but the evidence to date suggests that it is the alcohol itself, rather than other compounds contained in alcoholic drinks, that protects against heart disease.
But I would not recommend people start drinking specifically to protect the heart, as there are health risks involved in drinking moderate amounts of alcohol, and there are safer alternative ways to reduce the risk of heart disease, such as to start taking more physical activity, to eat a healthy balanced diet and to stop smoking.
OSB: What do we know about the dangers of binge drinking?
NA: The adverse health effects of heavy drinking are varied, devastating and affect all ages: in youth, alcohol tends to be related to mental and behavioural disorders, injuries and violence, whilst in middle- and late-age, heavy drinking is related to liver disease and certain cancers.
However, for people who drink more moderate amounts of alcohol, it is not yet known whether the pattern of drinking affects the long-term risks for cancer (i.e. whether drinking one drink every day or bingeing on seven drinks in one session at the weekend has the same effect).
OSB: We seem to get endless reports of new studies with conflicting conclusions. Why is it so difficult to carry out a definitive study?
NA: The main reason there have been so many conflicting findings is because most studies have been too small to detect reliably the effects of low to moderate amounts of alcohol on different health outcomes at the same time. Up until now, most studies have examined the association of alcohol on a single disease (eg a specific cancer type, or heart disease).
Many thousands of participants are needed to reliably compare rates of diseases within the same study population. Only by establishing these very large epidemiological studies, such as the Million Women Study in the UK (with over 1.3 million middle-aged women recruited 1996–2001), can we begin to directly compare future disease rates among women according to their usual alcohol consumption.
With linkage to both regional cancer registries and, more recently, hospital admissions databases, it is now possible to investigate the association of alcohol with cancer, heart disease and other outcomes in this population, and we will soon be in a position to comment on the overall risks and benefits of moderate alcohol drinking in women.
OSB: And do you have any advice as we look forward to all our Christmas celebrations?
NA: I don’t want to be a party-pooper and berate people who have a celebratory tipple at Christmas time, or even those who have one every day to celebrate life’s daily grind. However, the three wise men might advise middle-aged women not to overindulgence too much on a daily basis, especially if they have other risk factors for breast cancer.