Impact of wine bottle and glass sizes on wine consumption at home: a within- and between- households randomized controlled trial.

Background And Aims: Reducing alcohol consumption across populations would decrease the risk of a range of diseases, including many cancers, cardiovascular disease and Type 2 diabetes. The aim of the current study was to estimate the impact of using smaller bottles (37.5- versus 75-cl) and glasses (290 versus 370 ml) on consuming wine at home.

Design: Randomized controlled trial of households with cross-over randomization to bottle size and parallel randomization to glass size.

Setting: UK households.

Participants: A total of 260 households consuming at least two 75-cl bottles of wine each week, recruited from the general population through a research agency. The majority consisted of adults who were white and of higher socio-economic position.

Intervention: Households were randomized to the order in which they purchased wine in 37.5- or 75-cl bottles, to consume during two 14-day intervention periods, and further randomized to receive smaller (290 ml) or larger (350 ml) glasses to use during both intervention periods.

Measurements: Volume (ml) of study wine consumed at the end of each 14-day intervention period, measured using photographs of purchased bottles, weighed on study scales.

Findings: Of the randomized households, 217 of 260 (83%) completed the study as per protocol and were included in the primary analysis. There was weak evidence that smaller bottles reduced consumption: after accounting for pre-specified covariates, households consumed on average 145.7 ml (3.6%) less wine when drinking from smaller bottles than from larger bottles [95% confidence intervals (CI) = -335.5 to 43. ml; -8.3 to 1.1%; P = 0.137; Bayes factor (BF) = 2.00]. The evidence for the effect of smaller glasses was stronger: households consumed on average 253.3 ml (6.5%) less wine when drinking from smaller glasses than from larger glasses (95% CI = -517 to 10 ml; -13.2 to 0.3%; P = 0.065; BF = 2.96).

Conclusions: Using smaller glasses to drink wine at home may reduce consumption. Greater uncertainty remains around the possible effect of drinking from smaller bottles.