Have you completed the first module in this series about alcohol misuse?
Part one: Facts about alcohol.

CPD activity

Before you start reading this article, think about:

• What do I want to learn?
• What will I gain from this learning?
• What will my employer gain?
• What difference will it make to people who use my services?

Many factors affect the rate and extent of alcohol absorption in the body. These variables mean alcohol affects people in different ways, and can lead to physical and mental health problems as well as exacerbate existing conditions.

Pharmacokinetics

The active ingredient in all alcoholic drinks is ethanol, which is produced from sugar through yeast fermentation. Stronger alcoholic drinks such as spirits are produced by subsequent distillation, which increases their ethanol concentration.

• Absorption

Approximately 30 per cent of any alcohol is absorbed relatively slowly via the stomach, while the remainder is absorbed more rapidly via the intestines and distributed around the body.

The alcohol absorption rate depends on many factors, including the presence of food in the stomach. If someone has eaten carbohydrates, for example, the level of alcohol in their blood may be less than a quarter of the level of someone with an empty stomach. 

The higher the alcohol concentration in a drink, the faster the absorption rate, and carbonated beverages, such as champagne or those mixed with soda are absorbed faster than non-carbonated drinks. 

The body’s major organs, such as the heart and the brain, are exposed to the same concentration of alcohol as the bloodstream. The liver is one exception, as it receives blood directly from the stomach and small intestines and is therefore exposed to higher concentrations of alcohol.

The rate of absorption also differs depending on gender. Women tend to have a lower blood volume and more subcutaneous fat (very little alcohol enters fat stores) than men. Both of these factors lead to higher blood alcohol concentrations, even when the amount of alcohol consumed is adjusted for body weight. Women may also have lower levels of alcohol dehydrogenase enzymes in their stomachs than men, which means that less alcohol is broken down before absorption. The menstrual cycle also affects alcohol absorption, which is higher during pre-menstrual and ovulation stages.

Medication also affects absorption, especially if someone is taking concomitant medicines. Some medicines, such as antihistamines, promote gastric emptying so increase the alcohol absorption rate.