Physical Effects of Alcohol
Q. What is the mechanism by which alcohol gets into the body after you’ve swallowed it?
A. Alcohol goes into the stomach first and then passes into the first part of the small bowel, which is where most of it is absorbed. Next it goes through the liver from where it is distributed into the body as a whole.
Q. Where in the body is it actually broken down?
A. It’s broken down mainly by the liver, and the rate of breakdown corresponds to about one standard drink per hour. A small percentage is excreted in the urine or exhaled in the breath and a small percentage is also broken down by other organs in the body, such as the stomach, but it’s mainly in the liver that this takes place. The liver is the primary site of the metabolism.
Q. If I was to drink three or four drinks in quick succession, how rapidly will the alcohol end up in different parts of my body?
A. The peak alcohol concentration would be reached about 45 to 60 minutes after the dose was taken and you would have a blood alcohol concentration, depending on your sex and your body size and composition, of around .05 to .08 per cent. There is a big difference between how men and women handle alcohol, also between people of different body sizes, and that certainly has to be taken into consideration.
Q. What accounts for the difference between how men and women handle alcohol?
A. Women are certainly more susceptible to the effects of alcohol than men. There are three basic reasons why this is the case. First of all, the average women is lighter than the average man – that’s a fairly straightforward explanation. However, the body composition of men and women is different. In women, a higher proportion of the body is formed of fatty tissue, in the breasts and subcutaneous fat. That means that the volume of distribution for alcohol is lower in women than men, and that results in higher concentrations of alcohol affecting sensitive organs such as the liver, the heart, the brain, and so on. The third reason why women are more susceptible seems to be that less alcohol is broken down in the stomachs of women than men, so that a higher proportion of the alcohol they drink is actually delivered to the liver and then distributed into the body.
In men, has the alcohol has been largely deactivated by the time it’s absorbed?
In men, quite a substantial proportion of the alcohol has been deactivated by the time it gets into the liver. This has really been discovered only in the last three or four years, but it does seem to be one of the important factors explaining the difference in susceptibility between the sexes.
Q. Is there an explanation for why women are less able to break alcohol down in their stomachs than men?
A. It could be related to differences in the sex hormones. We know that the enzyme alcohol dehydrogenase is influenced by the sex hormones which are circulating, but it’s too early to give a categorical explanation for the difference at the moment.
Q. As to the main reason why women should drink substantially less than men, is it almost as if the body is like a bottle that is being filled up, and in women there’s less space?
A. That’s right. That’s a very good of way of putting it. The area into which the alcohol is distributed is much smaller in women than in men, which means that the concentration of alcohol in the body is higher in women. Therefore, the level of exposure of the brain, the liver, the heart and other sensitive organs is much greater in women.
So women really have it stacked against them, don’t they, as far as alcohol is concerned?
In many ways, yes. It’s important for women who commonly drink in mixed sex groups not to go one for one with their male friends, because they’re much more likely to suffer the acute effects of alcohol, and they’re much more likely to suffer physical harm in the years to come.
Q. Overall, does that mean that you get proportionally more women than men with alcohol problems?
A. No. Men still outnumber women in terms of the frequency of alcohol problems, probably because drinking has been much more a male thing to do in most societies than it has been a female thing to do. However, women who do drink are much more susceptible to the damaging effects of alcohol than men. Also, in regard to the protective effect of alcohol which occurs at moderate amounts, there are also differences between the sexes there.
Q. You’re talking about the effect of the ‘one or two glasses a day is good for you’ idea?
A. Yes. There’s now good evidence that the risk of developing heart disease is lower in people who are moderate alcohol drinkers than in total abstainers. In men, the peak effect seems to be at an alcohol intake of about two drinks a day, and in women the peak effect is at an alcohol intake of around about one drink a day.
Q. Coming to the more insidious side of alcohol and alcohol consumption, how much do you understand about alcohol addiction, especially by comparison with other kinds of substance addiction?
A. Addiction to alcohol is something that develops slowly. It creeps up on people and takes them unawares. I’ve had many patients in whom the first real sign of any harm from alcohol has been when they’ve suffered a major physical complication such as having a haemorrhage as a result of liver disease, or they’ve had severe problems with their memory as a result of the toxic effects of alcohol on the brain and nutritional deficiency. It’s not like cigarette smoking, for example. Nicotine is a powerfully addictive compound and people become physically addicted to it after having a relatively small number of cigarettes. For alcohol it’s quite different. Typically, the development of dependence, or addiction, takes many, many years. Also, importantly, some people can suffer considerable harm from alcohol without being addicted to it. Indeed, the majority of patients who would be seen in community health centres or by general practitioners, and who have some kind of alcohol problem, would not be addicted to alcohol. It would just be something that they do and enjoy, but don’t realise the potential harm that those high doses are causing them.
Q. Given that there are people who say that one or two glasses of alcohol could be good for you, but there’s also this potential for awful damage, what’s your feeling about how alcohol should (or shouldn’t) be used in our society? Do you think that people shouldn’t be drinking at all?
A. We should recognise that when the great majority of the population – about 75 per cent of men and women – drink alcohol, they do so responsibly and in ways that are very unlikely to cause them any harm. We have to acknowledge that the majority of people drink and enjoy alcohol and don’t suffer any really serious consequences from it. The strategy which we have recommended in recent years is to try to identify people who are putting their health and their social well-being at risk, to offer them brief advice on what the safe levels of drinking are for them, and to give them some tips about how to reduce their drinking safe levels and yet still enjoy their lives. There are now some quite powerful techniques which can result in a reduction in alcohol consumption of 30 or 40 percent in people who are hazardous drinkers.
My preference is for that approach to be developed in the years to come. The alternative is to try to increase the regulations on alcohol, to try to increase taxation. Certainly that would reduce consumption in the community as a whole. The problem with that approach is that it is unpopular amongst the great majority of people and it also brings with it the possible risk that if moderate drinkers become abstainers they might move from a low risk zone for cardiovascular disease to a high risk zone – that’s something I think we need to take into consideration. My general view is that the guidelines recommended by the National Health and Medical Research Council for safe and responsible drinking are appropriate and that we should do all that we can to look at our own drinking habits, to encourage people to take part in screening programs for hazardous drinking, and also to help general practitioners and other health care professionals offer people brief interventions throughout the health care system.
Q. From your perspective of working with alcohol, do you like to have a drink, or are you against drinking?
A. I do have a drink probably four days a week, something like that. I’m fortunate in that it’s never caused any particular problems. I’m not somebody who has the view that society should be abstinent. Most societies throughout history have been able to use alcohol without it causing major problems. There are some societies where it has caused very severe problems, but those societies have generally sorted things out and introduced appropriate laws and approaches to stop that.
Q. What part does genetics play?
A. The difference between the sexes is perhaps the most dramatic one in terms of susceptibility to alcohol, but there are also potent genetic influences. We know, for example, that alcohol problems tend to run in families. For many years this was just assumed to be children modelling behaviour on that of their parents, but we now know from fairly sophisticated studies that there is a prominent genetic component. Perhaps 40 or 50 percent of the reason why people develop a drinking problem can be explained along genetic lines.
We don’t know whether there is one gene or small group of genes which are the susceptibility genes for alcohol problems. My personal feeling is that there isn’t a single major gene which is involved but probably half a dozen genes which influence susceptibility. There are some candidate genes which have been identified already, for example. The dopamine receptor exists in two forms and the A1 allele, which is one of these forms, is found in a higher proportion of people with major drinking problems than it is in the population at large. So that’s one potential genetic marker. We’re involved in an international study looking for other genetic markers in different populations. I should think that within five years we will have a range of genetic markers of susceptibility. What this means is that, potentially, people can be screened for these markers of susceptibility and so can be given information from which they can make their own choices about drinking alcohol. I think it’s better for people to know that they have a genetic loading for susceptibility because then they can make an informed choice to be more cautious than average about their alcohol intake.
It’s all about information on which personal choice can be based.
© 1997 Australian Broadcasting Corporation