Does adding milk to tea delay gastric emptying?

BACKGROUND

Many preoperative fasting guidelines suggest that hot tea or coffee with milk added should be considered similar to solid food, allowing an interval of 6 h before commencing anaesthesia. There is little evidence to support these instructions, with recent guidelines undecided on the issue. This study aimed to establish whether there was a clinically significant delay in gastric emptying associated with adding a modest amount of milk to tea.

METHODS

This randomized controlled crossover study was conducted in 10 healthy volunteers. The paracetamol absorption technique and real-time ultrasound measurement of the cross-sectional area of the gastric antrum were used to assess gastric emptying after ingestion of 300 ml of black tea or 300 ml of tea with milk (250 ml black tea plus 50 ml of full fat milk).

RESULTS

The mean difference in the time to reach the peak paracetamol concentration (tmax) was -8 min [95% confidence interval (CI) -23.1 to 7] in favour of tea with milk. Ultrasound assessment indicated that the geometric mean of the half-time to gastric emptying (T₁/₂) after tea without milk was 22.7 (95% CI 12.7-40.9) min and after tea with milk 23.6 (95% CI 13.5-41.0) min (ratio 1.04) (95% CI 0.47-2.29).

CONCLUSIONS

This study demonstrated no difference in gastric emptying times when a modest amount of milk was added to tea. These findings suggest that it may be acceptable to allow patients to add a small quantity of milk to their tea or coffee and follow the same fasting restrictions applied to clear fluids.