Straight-sided beer and cider glasses to reduce alcohol sales for on-site consumption: A randomised crossover trial in bars

Background: Straight-sided glasses can slow the rate of lager consumption in a laboratory setting compared with curved glasses. Slower drinking rates may lower overall alcohol consumption. Glass shape is therefore a potential target for intervention. The aim of this randomised crossover trial was to estimate the impact of serving draught beer and cider in straight-sided glasses, compared with usual, predominantly curved glasses, on alcohol sales for on-site consumption in bars. Methods: Twenty-four bars in England completed two intervention periods (A) and two control periods (B) in a randomised order: 1) BABA; 2) BAAB; 3) ABBA; or 4) ABAB. Each period lasted two weeks and involved serving draught beer and cider in either straight-sided glasses (A) or the venue's usual glasses (>= 75% curved; B). The primary outcome was the mean volume (in litres) of draught beer and cider sold weekly, compared between A and B periods using a paired-samples t-test on aggregate data. A regression model adjusted for season, order, special events, and busyness. Findings: Mean weekly volume sales of draught beer and cider was 690.9 L (SD 491.3 L) across A periods and 732.5 L (SD 501.0 L) across B periods. The adjusted mean difference (A minus B) was 8.9 L per week (95% CI -45.5 to 63.3; p = 0.737). Interpretation: This study provides no clear evidence that using straight-sided glasses, compared with usual, predominantly curved glasses, reduces the volume of draught beer and cider sold for on-site consumption in bars.

Automated summary

The study found that there was no significant difference in the volume of draught beer and cider sold for on-site consumption in bars when using straight-sided glasses compared to usual, predominantly curved glasses.