The text below is the basis of a talk given by Christopher Snowdon, head of lifestyle economics at the Institute of Economic Affairs, at the Spectator annual health debate 2016. The debate was entitled: ‘Can we trust health advice?’

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.

Why would she misrepresent the evidence? I think there are two reasons.

If I may illustrate by analogy, when I first started secondary school at the age of 11, the teachers told us that we would be expected to do three or four hours of homework a night. Even at the time, this struck me as being optimistic on their part. I doubt that any of us were so conscientious. Speaking personally, I recall half an hour being the average, perhaps up to an hour on occasion.

Looking back, I think the teachers knew that we wouldn’t do three or four hours. I think they would have been very happy if we did one or two hours. They were doing something that behavioural economists call ‘anchoring’ — putting an unrealistically high number in our minds in the hope that we would settle for a lower number, but that the number would still be higher than the number we would have come up with if left to our own devices. If they had said we should do an hour, we might have settled for 20 minutes. If they had said half an hour, we might have settled for ten minutes.

That, I suspect, is what health authorities are doing when they tell us to have no more than seven drinks a week, or to have no more than seven teaspoons of sugar a day. We will probably exceed those guidelines, but we might think twice about exceeding them by two or three times — and those are the kind of levels at which health could genuinely be impaired.

If that’s what they’re doing, I think it’s a problem. Manipulating school children into doing their homework is one thing. Lying to adults about scientific evidence is quite another. The health benefits of moderate alcohol consumption are not an ‘old wives’ tale’, as Davies claims. They are supported by a huge body of evidence, but she doesn’t want us to be able to handle nuanced information. In public health, things are either good or bad, and she wants to portray alcohol as bad, hence the need to downplay the benefits and the rhetoric about there being ‘no safe level’. It’s nonsense, but it is a clear message and that’s what counts.

Second, there is a distinct possibility that these guidelines are not really aimed at us at all. The number of people who exceed the weekly drinking guidelines has been falling for years. By lowering the recommendations for men, Sally Davies has pulled two million more hazardous drinkers out of her hat. Similarly, although most people exceed the old sugar guidelines, sugar consumption has been falling for years. Now that the guidelines have been halved, it is almost impossible not to exceed them. By moving the goalposts, the problem is inflated, panic ensues, and the political agenda of the ‘public health’ lobby, with all its taxes, bans and gruesome warnings, is given a shot in the arm.

There is a telling comment in the minutes of one of the meetings held to reassess the drinking guidelines. It says that it is ‘important to bear in mind that, while guidelines might have limited influence on behaviour, they could be influential as a basis for government policies’. Influencing government policy is the real aim of the game. They don’t trust us to handle accurate information. As a result, we can no longer trust them to give us it.