Does adding milk to tea delay gastric emptying?

Area of Science:

• Anesthesiology
• Gastroenterology
• Pharmacology

Background:

• Current preoperative fasting guidelines often classify tea or coffee with milk as solid food, requiring a 6-hour fasting interval.
• There is limited evidence supporting the classification of milk-added tea/coffee as solid food, leading to uncertainty in recent guidelines.

Purpose of the Study:

• To investigate if adding a modest amount of milk to tea causes a clinically significant delay in gastric emptying.
• To provide evidence-based recommendations for preoperative fasting guidelines concerning milk-added beverages.

Main Methods:

• A randomized controlled crossover study involving 10 healthy volunteers.
• Gastric emptying was assessed using the paracetamol absorption technique and real-time ultrasound measurement of gastric antrum area.
• Volunteers ingested 300 ml of black tea or 300 ml of tea with milk (250 ml black tea + 50 ml full-fat milk).

Main Results:

• The time to peak paracetamol concentration (tmax) showed no significant difference between tea with and without milk (mean difference -8 min, favoring tea with milk).
• Ultrasound measurements indicated no significant difference in the half-time of gastric emptying (T₁/₂) between black tea (22.7 min) and tea with milk (23.6 min).
• The ratio of gastric emptying half-times was 1.04 (95% CI 0.47-2.29), indicating no substantial delay.

Conclusions:

• Adding a modest amount of milk to tea does not alter gastric emptying times.
• These findings support allowing patients to consume tea with a small quantity of milk under clear fluid fasting protocols.
• This could potentially shorten preoperative fasting periods for patients consuming these beverages.