A L C O H O L A N D H E A LT H

ALCOHOL AND THE HUMAN BODY

ISBN 2-9807330-8-3Legal deposit2006

TABLE OF CONTENTS

Introduction 1

Alcohol – Unlike anything else we eat 2It’s absorbed differently 3

It’s eliminated differently 4

It affects you differently 6

More information means better decisions 9

A L C O H O L A N D H E A LT HALCOHOL AND THE HUMAN BODY

1

Every five years, Éduc'alcool conducts a majorsurvey in Québec. In the most recent one, weasked people which drinking-related subject wasof greatest interest to them.

More than 70% of all respondents said theywanted to know the effects of alcohol on thehuman body.

In response to that overwhelming request,Éduc’alcool is pleased to add this new monographto its Alcohol and Health series. Its purpose is toprovide information and influence behaviour, usingsimple, easy-to-understand language.

Éduc’alcool believes strongly that one way toprevent alcohol abuse is to make sure that peopleknow exactly what happens to their bodies – andto the alcohol – when they drink.

People who are equipped with accurateinformation are more likely to be aware of thedangers of abusive drinking, and understand evenmore clearly the importance of drinking moderatelyand responsibly.

When it comes to drinking, there is no hard andfast rule that holds true for everyone. Each of usmust take our specific differences into accountas we make our own choices. Nonetheless, thepath that alcohol travels through body is the samefor everyone. And it remains true that excessive,abusive drinking and intoxication will always beunacceptable – socially, culturally and medically.

In other words, moderation is always in goodtaste.

The Éduc’alcool Board of Directors

INTRODUCTION

A L C O O L E T S A N T ÉL’ALCOOL ET LE CORPS HUMAIN

2

More than 80% of Quebecers drink alcoholregularly, most of them moderately. Anyone whodrinks should be aware that alcohol is not likeany other food. They should also know whathappens physiologically when they drink: howthe alcohol is absorbed, how it is eliminated,and the impact it has as it travels through the body.

ALCOHOL – UNLIKEANYTHING ELSE WE EAT

A L C O H O L A N D H E A LT HALCOHOL AND THE HUMAN BODY

3

Why does alcohol get into the bloodstreamso quickly?

Alcohol is absorbed very quickly by the blood and spreadseasily to all the organs. That’s because alcohol moleculesare very tiny. They don’t have to be broken down bydigestive enzymes to get into the blood, and they dissolveeasily in water and fat, both of which are primecomponents of the human body.

Why is alcohol absorbed more quickly when the stomach is empty?

Alcohol moves quickly from the mouth to the stomach andon to the intestines. Some of it is absorbed directly throughthe mucosal lining of the mouth and esophagus, some isabsorbed through the walls of the stomach and the restis absorbed by the intestines, mainly the small intestine.

If there is no solid food in the stomach or intestines, thealcohol will come into contact with the intestinal wallsmore easily and pass quickly into the blood. All the alcoholof one drink may well be absorbed within 30 minutes.

However, if your stomach is relatively full, the alcohol willstay there longer. The absorption process will be slowerand may take up to 90 minutes.

Why is stronger alcohol absorbed more slowly?

Beverages that are more than 20% alcohol irritate thelining of the stomach. This slows the opening of the pyloricvalve, through which the contents of the stomach passinto the small intestine. Drinking several shots of spiritsone after the other in the hope of getting drunk quicklymay actually produce a delayed reaction.

Why does alcohol go to your head so quickly?

Once it’s in the bloodstream, the alcohol spreads to allparts of the body and is distributed in all tissues containingwater. Because alcohol is carried by the blood, it followsthat it will be delivered particularly quickly to organs withmany blood vessels, such as the brain, the lungs and the liver.

It’s absorbed differently

mucous membranesof the mouth

esophagus

stomach

large intestine

small intestine

A L C O H O L A N D H E A LT HALCOHOL AND THE HUMAN BODY

4

Why is there alcohol in the breath you exhale and in breast milk?

Some alcohol (about 10%) is eliminated as is, throughurine or perspiration. It can also be eliminated through thebreath, since the bloodstream carries it to the lungs. Thisis why a breathalyzer can effectively measure your bloodalcohol level (breath alcohol testing device).

Nursing mothers should be aware that the concentrationof alcohol in breast milk is about 10% higher than in theblood, because of the high water content of the milk.

How is alcohol metabolized by the liver?

Most of the alcohol (about 90%) is eliminated by thebody’s metabolism. While the kidneys and gastro-intestinaltract play a role in this process, the liver is the organprimarily responsible for transforming the alcohol absorbedby the blood.

In the first stage of metabolism in the liver, an enzymecalled alcohol dehydrogenase transforms the alcohol intoacetaldehyde, a highly toxic substance that affects theentire body. This activates another enzyme – acetaldehydedehydrogenase – which transforms the toxic acetaldehydeinto inert, harmless molecules of acetate, or acetic acid.

Why do different people eliminate alcohol differently?

No matter how much or how little you drink, your liver canonly metabolize 15 17 mg of alcohol every hour. Thespeed at which it does so depends primarily on the numberof metabolic enzymes in the liver, which varies from oneindividual to the next and is thought to be geneticallydetermined. Other factors also influence the process.

It’s eliminated differently

liver

pure alcohol/ethanolacetaldehyde

acetate /acetic acid

Alcohol metabolism

Food: Full stomach or empty stomach?The speed at which alcohol is eliminated depends on theamount and type of food present in the gastro-intestinalsystem. During digestion, the stomach’s contents arepassed into the small intestine (a process known as gastricemptying). The higher the fat content of the food in thestomach, the more time is required for gastric emptying,and the slower the process of alcohol absorption.

Scientific studies have shown that people who drink aftera meal rich in fats, proteins and carbohydrates absorbalcohol more slowly than those who drink on an emptystomach.

Gender does matter: Me Tarzan, you JaneAll other things being relatively equal, if a woman and aman drink exactly the same amount, she will have a higherblood-alcohol level than he does. That’s because womengenerally weigh less than men and their bodies have ahigher fat content. Lower body weight means lower watercontent, so the alcohol is dissolved in a smaller amountof liquid. This results in a higher concentration of alcoholin the woman.

Because women are generally smaller than men, they alsohave less alcohol dehydrogenase in their bodies, whichmeans that a greater percentage of the alcohol womendrink remains in their blood.

Age matters, too: Teens and seniors, beware!Teens and older people don’t tolerate alcohol as well asothers, mostly because of their (generally) lower bodyweight. Consequently, as with women, the alcohol isdissolved in a smaller amount of liquid.

Also, teenagers have fewer alcohol-eliminatingenzymes in their livers than adults do.

Alcohol and medication:Unforeseeable reactionsSome medications can hinder the eliminationof alcohol, heighten or mask its effects, orprovoke unforeseeable reactions.

Conversely, alcohol can reduce the effectivenessof some medications or hinder their elimination.

A L C O O L E T S A N T ÉL’ALCOOL ET LE CORPS HUMAIN

6

It affects you differentlyWhy does alcohol have such an impact on the brain?

Before it reaches the liver, the alcohol in the blood affectsother vital organs that contain a lot of water and requirea significant volume of blood in order to function. The mostimmediately observable effects can be seen in the brain.

Alcohol restricts a number of brain functions by stimulatingthe brain’s pleasure centres. At first, the effects arepleasurable: there is a reduction in stress and inhibitions,and a sensation of either calm or excitement.

How you feel depends on your mood at the time. If youare sad or angry before you drink, the alcohol may initiallyput you in a better mood. But then the opposite occurs,and you may well end up even sadder or angrier than youwere before you started drinking.

Alcohol and stressAlcohol often goes hand-in-hand with, and even promotes,sociability, conversation, pleasure and a sense of well-being. Among the social and psychological benefits ofalcohol, some people report an increase in creativity; andalcohol also has a certain therapeutic value as a meansto reduce stress.

But while a small amount of alcohol may relieve stress inthe short term, it does absolutely nothing to treat thesource of the stress. In fact, studies show that the oppositeis true: over the long term, alcohol increases anxiety levels.When the anxiety persists, the desire to self-medicate withmore alcohol can lead to an alcohol dependency.

Alcohol and sleepPeople commonly believe that alcohol helps you sleep.Certainly, it can help you fall asleep. But alcohol interruptsnormal sleep cycles, and the morning after a night of heavydrinking may find you feeling tired and unwell, even if youhave slept a long time. What’s worse, alcohol can causeinsomnia and frequent sleep interruptions, in addition toexacerbating existing sleep problems.

Alcohol and sexAlcohol can cause or aggravate sexual problems. Abusivedrinking, for example, can make it difficult for men toachieve an erection and for women to achieve orgasm.

Why does alcohol change behaviour?

Numbing effectsAs your blood-alcohol level rises, your brain’s motor andsensory centres are affected. You begin to have difficultywith coordination and fine motor functions, and yourreaction time slows.

The effects can be minor or major, depending on howmuch you drink. If you have a blood-alcohol level of .08,or 80 mg of alcohol per 100 ml of blood – the legal limitfor driving a motor vehicle in Canada – your reaction timewill be 30% 50% slower than when you have no alcoholin your blood. For example, driving under the influence ofalcohol will make it difficult to brake quickly if the carahead stops suddenly.

AggressionAs you become intoxicated, your speech, thoughtprocesses and senses are affected. Your cognitive andverbal skills are diminished; and since these are the skillsthat allow you to resolve conflicts, there is a greaterlikelihood of aggressive and violent behaviour.

VomitingThe part of the brain that controls vomiting is affected by the alcohol and toxic acetaldehyde circulating in your blood.

DehydrationAlcohol also affects the pituitary gland, resulting inreduced secretions of the anti-diuretic hormone thatmaintains the body’s proper hydration level. Morespecifically, the kidneys are no longer able to reabsorbsufficient water from your urine, and your body ends upeliminating more water than it absorbs. The symptomsof dehydration are fatigue, back and neck pain, andheadaches.

Alcohol and young peopleRecent discoveries in neuroscience and child psychiatry showthat the brain is not really fully developed until after age 20. Thebrains of adolescents are therefore more vulnerable to alcohol-related damage than adult brains.

Other studies highlight the effects of alcohol on the ability to learnand make decisions.

The earlier children begin to drink with their peers, the greater therisk that they will develop an alcohol dependency later on.

HabituationThe immediate effects on the brain are often less apparentamong people who drink regularly, because they havedeveloped a strong tolerance for alcohol. As a result, theycan often drink a great deal without feeling too manyshort-term effects. Such tolerance is both metabolic – theliver processes the alcohol more quickly and efficiently –and functional – the person learns to compensate for thedeficits caused by alcohol.

Nevertheless, the harmful effects of drinking will be seenand felt in the long term. In fact, people whose bodies arehabituated to the immediate effects of alcohol aregenerally those who drink abusively.

A L C O H O L A N D H E A LT HALCOHOL AND THE HUMAN BODY

7

A L C O H O L A N D H E A LT HALCOHOL AND THE HUMAN BODY

8

Heart and cardiovascular systemJust one or two drinks can affect your heart rate, bloodpressure, circulation and contractions of the heart muscle,including its ability to pump blood through your body. Whilethese reactions are generally not considered significantfrom a clinical point of view, they can be more serious ifyou already suffer from cardiovascular problems.

Nonetheless, as of a certain age, regular, moderate drinkingcan provide some protection against cardiovascular diseaseand peripheral vascular disease.1

Among other things, alcohol causes the small bloodvessels beneath the skin to dilate, which increases bloodcirculation. You may have noticed that some heavy drinkershave a particularly ruddy complexion. What you’re seeingis the result of the dilated blood vessels.

The dilation of blood vessels also causes heat loss, anda drop in body temperature. Contrary to popular belief, itis very dangerous to drink alcohol to “warm up” when youare exposed to the cold.

IntestinesAs soon as even a small amount of alcohol is ingested,the intestines begin to secrete acid. As the blood-alcohollevel rises, secretions of pepsin, a digestive hormone, arereduced, leading to an irritation of the intestinal walls andeventually diarrhea.

PancreasThe pancreas produces insulin, which the body needs tocontrol blood sugar levels. Drinking causes a sudden spikein blood sugar; the pancreas responds by producing moreinsulin. This causes a rapid drop in blood sugar and thesymptoms of hypoglycemia – dizziness, headaches,difficulty concentrating, depression, anxiety, trembling, coldsweats, heart palpitations, loss of coordination, andstomach aches.

1Éduc’alcool, Alcohol and Health: The health benefits of moderate and regular alcohol consumption, 2005.

How does alcohol affect other vital organs?

Understanding the physiological effects of alcoholcan, among other things, help you calculate yourblood-alcohol level, taking into account the variousfactors that affect the rate at which your bodyabsorbs alcohol. This information is vital for anyonewho has to do something demanding like drive amotor vehicle or participate in physical activity.

It is certainly good to know how much alcohol youhave absorbed before you drive. But there are betterreasons for understanding how alcohol affects thevarious organs and systems in your body. More

information helps you make better choices. Whenyou have more knowledge, you tend to make moreenlightened decisions.

Ultimately, we hope that people who know moreabout the subject will understand the very realimpact alcohol has on the human body.

Well-informed people will be more conscious of theunpleasant and dangerous side-effects of abusivedrinking, and, we hope, more aware than ever thatmoderation is always in good taste.

MORE INFORMATION MEANS BETTER DECISIONS

Éduc’alcool wishes to thank the following organizations, whose publicationswere used in preparing this booklet:

• Institut national de la santé et de la recherche médicale (2001). Alcool :Effets sur la santé. Paris: INSERM.

• Institut suisse de prévention de l’alcoolisme et autres toxicomanies (2004).L’alcool dans le corps - effets et élimination. “Les jeunes et l’alcool”collection, Book 2. Lausanne: SFA/ISPA.

• National Health and Medical Research Council (2001). Australian AlcoholGuidelines: Health Risks and Benefits. Canberra: NHMRC.

Also in the Alcohol and Health series: The health benefits of moderate andregular alcohol consumption.

If you have a comment about this publication or want to order more copies, contact Éduc’alcool.

Téléphone: 1-888-ALCOOL1 (1-888-252-6651) Courriel : info@educalcool.qc.ca

educalcool.qc.ca

VERSION FRANÇAISE DISPONIBLE SUR DEMANDE.