The size of a wine bottle can influence the amount of wine drunk at home, according to the first study to examine this, which was led from the University of Cambridge. The study found that when people drank wine at home from 50cl bottles rather than the usual 75cl bottles, they drank about 4.5% less.
Alcohol is the fifth largest contributor to early death in high income countries and the seventh world-wide and there is widespread interest in ways to reduce consumption.
Larger portions and packages are known to increase consumption of food and non-alcoholic drinks, and larger wine glasses increase the amount of wine consumed.
So could the size of the bottles in which alcohol is packaged and sold influence how much people drink?
This study is the first to look at the effects of varying bottle sizes. It focused on consumption at home, where 80% of wine is drunk.
The researchers recruited 186 households for this study, selecting those with a moderate drinking pattern of between 1.5 to six litres of wine per week. The households were broadly comparable to consumers of alcohol in Britain, the majority of whom are white and of higher socioeconomic position.
During two 14-day study periods, households were requested to buy their usual amount of wine in 50cl or 75cl bottes, in random order. Each household photographed their bottles at specific intervals during the study to enable the researchers to measure both the volume they had consumed and the speed at which the wine was drunk.
The households reported on any additional wine that they consumed during the study period, such as that consumed out of the home. They also let the study team know if they had guests that drank from their study wine, or whether there were other events that affected their usual drinking habits (such as being ill). 166 households submitted the data needed to be included in the analysis.
When asked about their attitudes towards the 50cl bottles, 44% of respondents made positive comments, such as:
‘I had never thought about buying smaller volume bottles before but enjoyed drinking them as it was just the right amount to consume in an evening’.
‘I think I preferred the smaller bottles for regulating my drinking…. I drank less with the smaller bottles’.
36% of the respondents had more negative attitudes and 20% were neutral or expressed positive and negative attitudes:
‘I never usually buy 50cl bottles and think that will continue as there is not much difference in price therefore I think it’s better value buying the bigger bottle’.
‘It’s so easy to have a large glass, and as half the bottle is gone, you think “I may as well finish it off”. Whereas the larger bottles, you have a large glass, and know it will take a while to finish a bottle, so you are more likely to leave it for another night’.
This study suggests that, amongst households consuming between 1.5 and 6 litres of wine a week, buying wine in 50cl bottles, as compared with 75cl bottles, reduces the volume of wine consumed at home by around 4.5%. There was some uncertainty around this estimate, but if this effect is replicated in future research, encouraging people to buy wine in smaller bottles could be one way to help cut wine consumption at home.
First authors Dr Eleni Mantzari and Saphsa Codling suggested that one way in which smaller bottles may decrease consumption is by making people feel that they had reached the end of a drinking session when the bottle was empty. With less wine in a 50cl bottle, there is less available to drink. This reflects a tendency for people to consume in ‘units’ regardless of portion or package size.
A 50cl bottle is not too small to be considered too different from the norm – which might make people feel resistant – but is small enough to reduce consumption. But it’s hard to source non-premium wine in 50cl bottles, especially at the moment, and those that are available cost more per centilitre than the usual 75cl bottles.”
So fiscal policies that make 50cl bottles more affordable would be helpful, while still discouraging consumption, in keeping with the strong evidence that reducing the affordability of alcohol reduces its consumption.”
– Professor Dame Theresa Marteau, senior author and Director of the Behaviour Change by Design research unit
Funding was from the National Institute for Health Research Policy Research Programme (Policy Research Unit in Behaviour and Health) and the Wellcome Trust.
S Codling, E Mantzari, O Sexton, G Fuller, R Pechey, G Hollands, M Pilling, T Marteau. Impact of bottle size on in-home consumption of wine: a randomized controlled cross-over trial. Published in Addiction, 9 April 2020
Lucy Lloyd, communications manager, Primary Care Unit
About Behaviour Change by Design
Behaviour Change by Design aims to accelerate progress in changing behaviour by redesigning environments to improve health for all. Behaviour Change by Design is based at the Primary Care Unit and led by Professor Dame Theresa Marteau.