After consuming ethanol, the process of absorption begins. Ethanol is a small polar molecule absorbed by passive diffusion slowly from the stomach and more rapidly from the small intestine due to the large surface area created by the presence of villi. Therefore, the rate of gastric emptying plays a key role in determining alcohol’s absorption rate (5). While many factors influence gastric emptying, components of the beverage itself also affect the absorption rate. For example, carbon dioxide in alcohol-containing carbonated drinks (e.g., champagne) may speed up ethanol absorption by accelerating gastric emptying (64, 65), while beverages high in carbohydrates, like beer, may slow gastric emptying and delay alcohol uptake into the bloodstream (66, 67). The alcohol concentration in a beverage also significantly impacts its absorption rate. For beverages containing <30% ABV, the higher the concentration, the faster the absorption rate, leading to higher peak BAC levels (68). However, above 30% ABV, ethanol can irritate the mucosa and cause pylorospasm, which delays gastric emptying (69–71).
