Alcohol absorption is the process of how alcohol enters the bloodstream. Once in the bloodstream, alcohol gets distributed throughout the body and into various tissues and organs until the metabolic process eliminates it. Understanding how these factors contribute to intoxication is key in any discussion of DUI/DWI.
Following a traffic stop for a suspected DUI/DWI, police officers check the subject’s blood alcohol concentration (BAC) level. This value reflects how much alcohol is in the body, and it is a result of the type and quantity of alcoholic beverage consumed, gender, weight, and metabolic rate of elimination. Consequently, this process is not the same for everyone. Ultimately, BAC measures the difference between absorption and elimination. This difference is the “blood alcohol curve.”
How is Alcohol Absorbed into the Body?
Following consumption, approximately 20 percent of the alcohol is rapidly absorbed into the bloodstream. The rest is absorbed through the stomach and small intestine. The liver then converts the alcohol into acetaldehyde by the enzyme dehydrogenase (ADH).
Once the alcohol reaches the bloodstream, the blood transports it throughout the body where it diffuses into fluids and tissues based on their water content. As the BAC decreases, the alcohol diffuses from the tissues and other fluids back into the bloodstream for elimination.
Rate of Absorption
The rate of absorption is a result of the stomach’s emptying time. In other words, if one consumes a lot of alcohol—or if the alcohol is a higher concentration—the rate of absorption is generally faster.
For those who engage in normal social drinking, peak BAC level generally occurs within 30 to 60 minutes after consumption. In cases where one consumes a large amount of alcohol over a short time—or if one eats a large amount of food with alcohol—this absorption period may take up to six hours.
Factors that Affect Alcohol Absorption
There are several factors that affect alcohol absorption. These include:
- Body tissues—different tissues absorb at different rates. For example, muscle tissue absorbs more rapidly than fat tissue.
- Gender—females generally have more fat tissue than males and lower levels of ADH, thus making them more susceptible to higher BACs than males.
- Body size and weight—as would be expected, smaller people become more intoxicated than larger ones because of lower body water content.
- The amount of food in the stomach—because of the small intestine’s large surface area, the lack of food increases alcohol’s absorption rate. Additionally, foods high in protein tend to slow alcohol absorption.
- Mood—changes in mood can affect alcohol absorption, especially stress, depression, or anxiety.
- Age—older people, especially senior citizens, are especially vulnerable to alcohol because of decreases in body water, muscle tissue, and metabolism, as well as certain medications which can interfere with alcohol absorption.
- Type of beverage— this is one of the most commonly thought of factors that can affect BAC. For instance, carbonated or mixed alcoholic beverages such as wine coolers, champagne, or sodas mixed with alcohol—as well as beverages with a higher alcohol concentration such as multiple alcoholic beverages (Long Island Ice Tea, Black Russians, etc.) and hot alcoholic beverages—are more quickly absorbed.
- Illness/Fatigue—these often come with dehydration which can increase alcohol absorption.
- Rate of consumption—the faster one drinks, the higher one’s BAC.
The body eliminates alcohol via metabolism and excretion. Metabolized alcohol is burned as food would be, thus producing water and carbon dioxide. Excreted alcohol leaves the body unchanged, such as through the breath, saliva, sweat, and urine.
For each person, alcohol elimination occurs at a constant rate. This rate is typically between 10-20 mg% per hour; however, the average rate of elimination is usually between 13 and 18 mg% per hour.
Understanding alcohol’s path through the body and what factors affect intoxication is critical for individuals who do, in fact, consume alcohol to reduce the potential for DUI/DWI and the serious problems which can occur.