Scientific evidence supports the common observation that carbonated alcoholic beverages seem to take effect more rapidly. Studies show that dissolved carbon dioxide accelerates the rate at which alcohol enters the bloodstream. “Drunk faster” refers to achieving a higher peak Blood Alcohol Concentration (BAC) in a shorter period after consumption. This acceleration is primarily due to changes in how quickly the liquid moves through the digestive system, allowing peak BAC to be reached significantly sooner when a carbonated mixer is used.
The Mechanism of Accelerated Gastric Emptying
Alcohol is absorbed primarily in the small intestine, which possesses a far greater surface area than the stomach. The speed at which an alcoholic drink moves from the stomach to the small intestine, a process known as gastric emptying, is the single most important determinant of alcohol absorption rate. Carbonated beverages contain dissolved carbon dioxide (\(\text{CO}_2\)) which, upon ingestion, causes the stomach to distend rapidly.
This mechanical distension of the stomach acts as a signal to the body to accelerate the digestive process. The pressure from the gas causes the pyloric sphincter, the muscular valve at the base of the stomach, to relax and open prematurely. This action bypasses the normal digestive timeline, allowing the liquid containing the alcohol to be “dumped” into the small intestine much faster than a non-carbonated drink.
By accelerating gastric emptying, carbonation ensures that ethanol reaches the small intestine’s extensive absorptive surface more quickly. Non-carbonated liquids remain in the stomach longer, slowing the rate at which alcohol enters the circulatory system. This mechanism explains why individuals who consume bubbly drinks experience the effects of alcohol sooner, though the total amount absorbed remains the same.
How Carbon Dioxide Influences Absorption Rates
In addition to accelerating gastric emptying, dissolved carbon dioxide has a secondary, direct impact on the body’s vascular system. When \(\text{CO}_2\) is absorbed across the stomach and intestinal walls, it acts as a local vasodilator. A vasodilator is a compound that causes blood vessels to widen, which increases blood flow in the surrounding tissue.
This localized increase in blood flow to the stomach and small intestine is an important factor in absorption. As alcohol is absorbed into the capillary beds beneath the intestinal lining, the increased blood flow ensures that the ethanol molecules are transported away from the absorption site and into the general circulation more rapidly. This expedited transport contributes to the quicker rise in Blood Alcohol Concentration.
This creates a two-pronged physiological acceleration: the physical movement of liquid into the small intestine is sped up, and the subsequent rate at which alcohol enters the bloodstream is also hastened. This dual action of \(\text{CO}_2\) helps explain the pronounced effect observed with carbonated beverages.
Variables That Modify the Carbonation Effect
Several practical factors can significantly alter the degree to which carbonation accelerates alcohol absorption. High alcohol concentrations (above 30% ABV) typically irritate the stomach lining and slow gastric emptying. However, diluting these spirits with a carbonated mixer creates an ideal scenario for rapid absorption, as the carbonation overcomes the inhibitory effect while accelerating the liquid’s transit.
The presence of food in the stomach is another highly influential factor. Eating a meal before or while drinking slows gastric emptying substantially, which can counteract the acceleration caused by carbonation. Food acts as a buffer, with studies showing that the presence of a meal can reduce the peak BAC achieved by 20 to 57 percent compared to drinking on an empty stomach.
The speed at which the drink is consumed also plays a clear role in maximizing the carbonation effect. Rapidly consuming a large volume of a carbonated alcoholic beverage forces the stomach to deal with both the liquid and the gas load all at once. This maximizes the distension signal and the premature opening of the pyloric sphincter, leading to the fastest possible rate of alcohol delivery to the small intestine.