7.1: The Use of Alcohol

What is a “drink”?

In the United States, a standard drink contains 0.6 ounces (14.0 grams or 1.2 tablespoons) of pure alcohol. Generally, this amount of pure alcohol is found in:

• 12-ounces of beer (5% alcohol content).
• 5-ounces of wine (12% alcohol content).
• 1.5-ounces of 80-proof (40% alcohol content) distilled spirits or liquor (e.g., gin, rum, vodka, whiskey).

Understanding Intoxication Levels: Blood Alcohol Concentration (BAC)

A blood alcohol test measures the level of Alcohol in your blood. This is typically done by using a breathalyzer or a blood test. Typically a blood alcohol concentration (BAC) greater than 0.08% is an indicator of intoxication, it means that you have 0.08 g of alcohol for every 100 ml of blood in your body. All states in the United States have adopted 0.08% as the legal limit for operating a motor vehicle for drivers aged 21 years or older (except for Utah, which adopted a 0.05% legal limit in 2018).

The liver is the main organ that processes, or metabolizes, alcohol and it can only process a small amount at a time, which is on average about one standard drink per hour. If you drink more alcohol than your liver can process then you will begin to feel the effects of intoxication. As blood alcohol concentration (BAC) increases, so does the effect of alcohol—as well as the risk of harm. When BAC reaches high levels, blackouts (gaps in memory), loss of consciousness (passing out), and death can occur.

It is important to recognize that the “one drink per hour” is an average and the actual time it takes your body to metabolize alcohol can vary for each person, for example it varies between men and women, whether you have eaten food, and the amount of alcohol consumed.

Examples of BAC Differences

• A male and female who weigh the same, eat the exact same meal, and drink the same amount of alcohol will have different BAC. Women tend to have higher body fat percentage than men and less total blood volume, which means there will be a higher concentration of alcohol in their blood thus increasing their BAC.
• Genetic differences can lead to differences in the amounts of enzymes that breakdown alcohol thus impacting the bodies ability to metabolize alcohol and increasing BAC.
• Females have lower amounts of an enzyme called Alcohol dehydrogenase (ADH). ADH is responsible for metabolizing alcohol in both the stomach and the liver. Since women have lower amounts of the enzyme they will have higher BAC than Males.
• A person who regularly drinks can build up tolerance because their body may increase production of the enzymes that breakdown alcohol.
• A person who drinks excessively for a long time might cause liver damage, which means their liver cannot effectively metabolize alcohol thus increasing their BAC.
• Men have a greater ratio of muscle to fat than do women. Muscle has a large amount of blood that flows through the muscle tissue. Fat has a much smaller amount of blood. The functional difference this makes is that alcohol is more diluted in a man’s body due to this larger volume of blood. Since women tend to have a higher percentage of body fat than men, this results in a higher BAC level for women compared to men.
• As the percentage of body fat increases, the BAC increases—this is because the total body water is lower, and that means that the alcohol is confined to this smaller volume.
• Absorption of alcohol is dependent on how quickly it can move through your stomach, this is called the gastric emptying rate. If your stomach is empty, gastric emptying increases, but if your stomach is full the gastric emptying slows down. Thus a full stomach will mean that the alcohol will take longer to absorb.

Alcohol Consumption Levels

Although the majority of U.S. adults consume alcoholic beverages, the Dietary Guidelines for Americans recommends limited consumption of alcohol and encourages people who have never drank alcohol to continue to abstain.

For those who choose to consume alcohol it is recommended to limit yourself to a moderate consumption level which is defined as up to 1 drink per day for women and up to 2 drinks per day for men.

People should avoid excessive alcohol consumption, which includes binge drinking, heavy drinking, and any drinking by pregnant women or people younger than age 21.

Binge drinking is the most common form of excessive drinking. About 66 percent of adults ages 21 through 59 report alcoholic beverage consumption in the past month, and of those, approximately half report binge drinking, sometimes multiple times per month, which can lead to high BAC levels.

A person is considered to be a binge drinker if they consume the following:

• For women, 4 or more drinks during a single occasion.
• For men, 5 or more drinks during a single occasion.

A person is considered to be a heavy drinker if they consume the following:

• For women, 8 or more drinks per week.
• For men, 15 or more drinks per week.

There are some people who should not drink any alcohol, including those who are:

• Younger than age 21.
• Pregnant or may be pregnant.
• Driving, planning to drive, or participating in other activities requiring skill, coordination, and alertness.
• Taking certain prescription or over-the-counter medications that can interact with alcohol.
• Suffering from certain medical conditions.
• Recovering from alcoholism or are unable to control the amount they drink.