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Children are faced with a whole new set of responsibilities as they grow into young adults, including the ability to legally purchase and drink alcohol. Help them make healthy choices by talking about how alcohol affects the body and what factors contribute to their body’s reaction to alcohol.
How does alcohol affect the body, and why do people drink? Understanding how alcohol works can help with setting limits to avoid over drinking or binge drinking.
The alcohol you drink moves into the bloodstream from the stomach and the small intestine. The blood then carries alcohol to the brain. The amount of alcohol in the blood is called Blood Alcohol Content (BAC). The higher your blood alcohol level, the greater the slow-down effect on your brain and other parts of the central nervous system.
Alcohol is largely metabolized (broken down into carbon dioxide and water) by the liver for removal by the lungs and urine. When all the alcohol is processed and eliminated from the body, BAC returns to zero.
BAC is usually given as a percentage, representing the weight of alcohol per volume of blood and measured in terms of milligrams of alcohol per 100 millilitres of blood. For example, a BAC of 0.08 per cent is 80 milligrams of alcohol for every 100 millilitres of blood.
What Happens as Blood Alcohol Content (BAC) Rises
Alcohol starts slowing a person’s thinking, movements and speech as soon as it reaches the brain. But how and how much it affects a person’s behaviour - and how obvious it is to others - depends on the person’s drinking experience (including development of tolerance) and their situation. Here’s a scale of BAC levels and what may be experienced as BAC rises.
- .00 = Relaxed buzz
- .05 = Less inhibited, more sociable feeling of well-being
- .10 = Serious impairment of motor co-ordination and judgment ability
- .15 = Sloppy, disoriented demeanour
- .20 = Memory blackouts, danger of choking on vomit
- .25 = Medical assistance may be necessary
- .30 = Hospitalization may be required Passed out in a stupor
- .35 = Coma
- .40 = Death from respiratory failure
What affects Blood Alcohol Content (BAC)
- Amount: The more alcohol, the higher the BAC.
- Speed: The faster the drinking, the higher the BAC.
- Absorption: Food in the stomach slows down the rate of absorption of alcohol (meaning BAC rises more gradually in a body with a full stomach than in a body with an empty stomach).
- Weight: The smaller the body size, the higher the BAC for the same amount of alcohol (larger bodies have more water than smaller bodies to dilute alcohol).
- Gender: A woman will have a higher BAC than a man after drinking the same amount because
- women’s bodies have less water - 50% compared to 60% for men,
- women also have smaller livers and less of the enzyme involved in metabolizing or breaking down alcohol, and
- women’s hormonal cycles and birth control pills impact metabolism rates.
- Age: People tend to lose lean body mass as they age, resulting in more body fat and less water in the body to dilute alcohol. Older bodies also process alcohol less effectively, putting an extra burden on the liver and producing a higher blood alcohol content.
- Metabolism: the liver metabolizes alcohol at a fairly fixed rate (about .016% BAC every hour for men, a lesser amount for women).
- Time: Despite common beliefs that coffee, cold showers or exercise can quickly sober you up, time is the only thing that can bring BAC back to zero.
How to Estimate Blood Alcohol Content (BAC)
BAC can be measured through breathalyzer instruments, like those used by police to prevent people from driving under the influence.
Use BAC tables or online calculators to see what your blood alcohol level might be while drinking. These tools aren’t 100 per cent accurate, but they a rough guide to show how multiple drinks overtime affects BAC.
Canada's Low-Risk Drinking Guidelines
Canada’s Low-Risk Alcohol Drinking Guidelines state you can reduce your long-term and short-term health risks by drinking no more than:
- 10 drinks a week for women, with no more than two drinks a day most days and no more than three on special occasions,
- 15 drinks a week for men, with no more than three drinks a day most days and no more than four on special occasions.
And, plan non-drinking days every week to avoid developing a habit.