Tuesday, January 15, 2008

Magic numbers: 14, 21, 35, 50, 60? [updated]

No, these are not my lottery numbers, but the sorts of numbers that appear regularly in any column about wine consumption at the moment.

In summary:
14: the weekly maximum recommended alcohol intake for women
21: the weekly maximum recommended alcohol intake for men
35: 15-35 units a week being the "hazardous" level for women doing them "long-term harm"
50: 22-50 units a week being the "hazardous" level for men doing them "long-term harm"
60: "Trebles all round"

I am not aware if other countries have similar measures, so let me deal with the UK situation for now and if it applies wherever you are, then maybe you can modify the numbers accordingly**

I have never understood where these numbers came from, and how exactly they link to scales of harm. For example, some questions that come to mind would be:

* How much worse are 22 units than 21?
* What about those who have 21 units in one go, versus those who have them evenly over the week?
* How long do you need to be staying above 21 to damage yourself?
* Can you average it out over a couple of years? How about over a lifetime (I could cash in on a relatively late start to my drinking career)?

Rather than focus on the amount of alcohol taken in "on average", and thus picking a number relatively at random, wouldn't it be better if we were encouraged to monitor our health better? A dodgy (but not yet irreversibly bad) liver test result would be a lot more motivating than simply sitting down and counting alcohol units to realise you were above the recommended level.

The recent announcement by the UK government that they would finally turn the NHS into an organisation that supported prevention of disease, rather than trying to cure those who are already sick, could be good news. Wouldn't it be better to go to the doctor, feeling healthy and discover that you have been a little too liberal with your pouring and that cutting back for the next couple of months or years will get you back on track, than to know nothing until you liver packs in and you join the transplant queue?

My worry about this is that the UK government in particular is likely to use this as a stick to beat society, setting up league tables and legislating on ways to force people to comply rather than educating and supporting individuals' choices. I can see how it would turn us all into guilty teenagers, worried about whether 'they' found out we'd been sampling from the spirits cabinet.

Whilst I totally agree that alcohol abuse is a major problem, I'm not sure that we have yet found a way of having a sensible discussion about it.

Is anyone aware of a country that has managed to have such a discussion? And anyone know where the numbers above come from?

Here are some additional links on the subject matter as suggested by Peter in the comments. I'll add more as I come across them:

Drinks Limits 'Useless' - The Times 20 October 2007
Unit of Alcohol - Wikipedia
Estimating alcohol consumption from survey data (UK) - this is an official PDF from the UK National Statistics office

** It is ALWAYS worth reminding people how to calculate these units as any rule of thumb is likely to be misleading - and a serious underestimation.


Peter May - The Pinotage Club said...

I have never understood where these numbers came from

A scientist on the panel that recommended them says that they were plucked out of thin air and they have no scientific meaning.

If you do a news Google you'll find some newspaper articles about it

Robert McIntosh said...

Thanks Peter. I thought I had heard that before but I was worried about being too definite about that point.

I shall research it and maybe post them up as a resource.

Andrew Brown said...

Another link for your Robert.

This one is from theOffice for National Statistics on how they calculate the amount we're drinking and why they think we've been underestimating the number of units.

Expect lots of stories about this once the survey figures start rolling in.

gopaz said...


I couldn't agree with you more. What better way to distance someone from their health than throwing around random numbers that have no personal significance.

It's similar to weight. Let me see my thighs in the mirror and I promise that I'll get on that treadmill right quick before I would with a simple scale reading. Easy to rationalize the machine was broken ;-)

If you give people both the tools and confidence to make sound decisions for themselves, they will. It's called prevention. But if you continually whip them when their down, throwing erroneous numbers their way instead of practical advice, you've already lost.