Before answering the question of whether we can trust health advice we must first ask: ‘Which health advice?’ It varies so much over time and between countries. In 1979, the government advised men to drink no more than 56 units of alcohol a week. This was later reduced to 36 units, then 28 units and then 21 units. Last month, the Chief Medical Officer reduced it once again, this time to 14 units. Upon announcing this, she also asserted that there is no safe level of drinking and that the health benefits of moderate alcohol consumption were ‘an old wives tale’.
Male drinking guidelines vary enormously around the world, from 52 units a week in Fiji to 35 units in Spain, all the way down to seven units in Guyana. There is no other country in the world that has the same guidelines as the UK. The day after Sally Davies released her report, the US National Institute on Alcohol Abuse and Alcoholism announced the results of its review of alcohol guidelines and maintained the recommendation for men of up to 25 units per week. This government organisation estimates that 26,000 deaths a year are prevented by moderate alcohol consumption thanks to reduced risk from heart disease, diabetes and stroke. In America, the guidelines for women are lower than they are for men, as they are in all but a handful of countries worldwide. Britain is now one of the few.
Therefore, in order to trust this latest piece of health advice from our Chief Medical Officer, we must believe not only that every previous Chief Medical Officer got it wrong but that every other country in the world has got it wrong. That requires a degree of patriotism that I am unable to summon up, particularly since the current advice bears no relationship whatsoever to the scientific evidence.
The graph represents the relationship between alcohol consumption and mortality. It is, I think, well known that the relationship is J-shaped. This particular J-curve is based on 34 prospective epidemiological studies which collect data on how much people drink and then follow them over a period of years with a view to seeing if they die and what they die of. As this graph shows, the risk of death declines substantially at low levels of alcohol consumption and then rises, but it does not reach the level of a teetotaller until the person is consuming somewhere between 40 and 60 grams of alcohol a day, which is to say between 35 and 50 units a week.
This J-shaped association was identified decades ago and has been repeatedly shown in studies from around the world. There are people in the temperance and ‘public health’ lobbies who do not want to accept the benefits of alcohol consumption. As a result, this epidemiological finding has been subject to more scrutiny than anything else in the field of alcohol research. It is precisely because it has been subjected to the greatest scrutiny that we know it to be robust.
It has been suggested, for example, that some of the teetotallers in these studies are former heavy drinkers who are inherently less healthy because of their old drinking habits. To test this, studies have been conducted to compare people who have never drunk with people who drink moderately, but the association remains — the teetotallers still tend not to live as long.
It has also been suggested that teetotallers lead unhealthy lives in other respects, thus confounding the results. However, it turns out that lifelong teetotallers tend to lead healthier lives than drinkers, being less likely to smoke and more likely to have a better diet, so that doesn’t stand up as an explanation either.
The only real pitfall in this kind of research is the problem of people under-reporting how much they drink. The amount of alcohol sold in the UK is about twice the amount that people claim to drink, so unless we throw away a huge amount of booze, it is certain that people either forget about how much they drink or they deliberately lie to researchers. In either case, we can assume that the people who say they consume two drinks a day are probably consuming three or four drinks, in which case the amount that you have to drink to assume the same level of risk as a non-drinker is even more than this graph suggests.
What is a safe level of drinking? Sally Davies says there isn’t one. In so doing she is encouraging the public to believe that the only safe level is zero. But that is not what the epidemiology shows at all. It would appear that you can drink significantly more than 14 units a week — or two units a day — and have a lower mortality risk than a teetotaller.