Monkeys usually prefer ripe fruits with approximately 1 percent
alcohol content but avoid overripe fruits with 4 percent alcohol
and lower sugar content. Anecdotally, humans often consume
alcohol with food, suggesting that drinking with food is a
natural combination. For millions of years, the amount of
alcohol consumed by our ancestors was strictly limited, and the
situation did not change even 10,000 years ago when humans
became agriculturists and could produce plenty of barley and
malt, the raw material for fermentation. Yeasts stop producing
alcohol when the alcohol level reaches between 10 and 15 percent
because yeasts start dying at this alcohol concentration.
Ancient beers and wines probably contained only 5 percent
alcohol until alcohol distillation was invented in Central Asia
around AD 700. Then drinks with a higher alcohol content became
available and the history of alcohol abuse by humans began.
The first historical evidence of alcoholic beverages came from
an ar-chaeological discovery of Stone Age beer jugs from
approximately 10,000 years ago. The first palm date wine was
probably brewed in Mesopotamia. Evidence of wine appeared in
Egypt about 5,000 years ago—Osiris was worshipped as a wine god
throughout the nation. beer was probably brewed in ancient Egypt
and both wine and beer were offered to the gods. Egyptians used
alcoholic beverages for pleasure and rituals, and for medical
and nutritional purposes. However, even in ancient times the
Egyptians were aware of the harmful effect of excess consumption
of alcohol and emphasis was on moderate use. The earliest
evidence of alcohol use in China dates back to 5000 BC when
alcohol was mainly produced from rice, honey, and fruits. A
Chinese imperial edict ca. 1116 BC made it clear that the use of
alcohol in moderation was the key and was prescribed from the
heavens. In ancient India, alcoholic beverages were known as “sura,”
a favorite drink of Indra, the king of all gods and goddesses.
Use of such drinks was known in 3000–2000 BC, and ancient
Ayurvedic texts concluded that alcohol was a medicine if
consumed in moderation but a poison if consumed in excess. Beer
was known to Babylonians as early as 2700 BC.
Yeast can produce alcoholic beverages with up to 15 percent
alcohol content. In order to produce a higher alcohol content, a
process known as distillation is needed. Distilled spirits
originated in China and India ca. 800 BC, but the distillation
process became common in Europe only during the eleventh century
and later. According to a survey by the U.S. government of
adults ages eighteen and older, approximately 50 percent of
adults are currently drinkers (at least twelve drinks in the
past year) and 14 percent are infrequent drinkers (one to eleven
drinks in the past year). In addition, 6 percent are former
regular drinkers, 9 percent are former infrequent drinkers,
while 21
percent are lifetime abstainers. Among current drinkers 61
percent are men and 42 percent are women.
According to a 2006 report by the National Institute of Alcohol
Abuse and Alcoholism, each year approximately 5,000 young people
under the age of twenty-one die as a result of underage drinking
(approximately 1,900 deaths from motor vehicle accidents, 1,600
as a result of homicide, 300 from suicide, and others from
injuries such as falls, burns, and drowning. Drug Use and Health
Report published in November 2008, more than one-quarter of
people ages twelve to twenty (28.1 percent) used alcohol in the
past month, 51.1 percent of ages eighteen to twenty, 25.9
percent of ages fifteen to seventeen, and 6.1 percent of ages
twelve to fourteen. This is a shocking statistic because alcohol
has a devastating effect on the developing brain of a
twelve-year-old person. Nearly one-third of the current underage
alcohol drinkers (30.6 percent) paid for the last alcoholic
drink they consumed, 14.6 percent got it free from another
underage person, 8.5 percent received it from another relative,
and an alarming 5.9 percent received their last drink from a
parent or guardian. People who start drinking at an early age
have a much greater risk of becoming alcohol dependent later in
life than individuals who start drinking at age twenty-one or
older. Alcohol can be considered a psychoactive drug because it
has complex interactions with various neurotransmitters and
receptors in the brain, producing pleasurable effects when
consumed in moderation.
However, with excess consumption, the positive effects of
drinking are replaced by negative effects, such as anxiety and
depression. If consumed in moderation, alcohol can protect
against age-related dementia and Alzheimer’s disease, but if
consumed in excess it can cause severe brain damage. In
addition, alcohol shares many pathways of various psychoactive
drugs for its pharmacological actions. Alcohol, like any drug,
has prophylactic effects in preventing many diseases, including
coronary heart disease (the number one killer in America),
stroke, various cancers, diabetes, arthritis, and other
diseases, as well as increasing longevity (see chapter 4).
However, if consumed in excess, it is detrimental to health (see
chapter 5). Therefore, like a drug, alcohol is effective in low
doses and toxic in higher doses.
Like a drug, alcohol is metabolized by liver enzymes, and a
toxic metabolite of alcohol known as “acetaldehyde” is
generated. If acetaldehyde is accumulated in the body due to
excess alcohol intake, it can cause liver damage. Also, a man
drinking the same amount of alcohol would have a lower peak
blood alcohol level compared to a woman with the same body
weight. This gender difference in the blood alcohol level is
related to the different body water content between a man and a
woman. Alcohol loves water and distributes into the aqueous part
of the blood known as serum.
Because a woman has less body water content (52 percent on
average) than a man (61 percent average), less water is
available to dissolve the same amount of alcohol compared to a
man. Some studies also report that women are more susceptible
than men to alcohol-related impairment of cognitive functions.
Women also metabolize alcohol more slowly than do men because
the concentration of alcohol dehydrogenase (ADH) is usually
lower in women compared to men. Hormonal changes also play a
role in the metabolism of alcohol in women, although this
finding has been disputed in the medical literature. Some
studies suggest that women metabolize alcohol at a higher rate
during the luteal phase of the menstrual cycle (days 19–22 of
the cycle), but a few days before menstruating, a woman’s
alcohol metabolism may slow down. In general, a child will
metabolize a drug faster than a younger or middle-aged adult,
and an elderly person (older than sixty-five) will metabolize a
drug more slowly than a younger or middle-aged adult. Metabolism
of alcohol changes with advancing age because the activity of
the enzymes involved in alcohol metabolism diminish with age.
Water volume also reduces with advancing age. An elderly person
would have a higher blood alcohol level from consumption of the
same amount of alcohol compared to a younger person of the same
gender.
The acetaldehyde produced due to the metabolism of alcohol,
regardless of the pathway, is subsequently converted to acetate
as a result of the action of mitochondrial aldehyde
dehydrogenase (ALDH2). Acetaldehyde is fairly toxic compared to
ethanol and must be metabolized quickly (equation 2.3).
Acetate or acetic acid then enters the citric acid cycle, which
is a normal metabolic cycle of living cells, and is converted
into carbon dioxide and water. From the chemical point of view,
the body burns (oxidizes) alcohol into carbon dioxide and water,
and this process generates calories.
Alcoholic beverages should not be consumed by some individuals,
including those who cannot restrict their alcohol intake, women
of childbearing age who may become pregnant, pregnant and
lactating women, children and adolescents, individuals taking
medications that can interact with alcohol, and those with
specific medical conditions. Alcoholic beverages should be
avoided by individuals engaging in activities that require
attention, skill, or coordination, such as driving or operating
machinery. Heavy consumption of alcohol leads not only to
increased domestic violence, decreased productivity, increased
risk of motor vehicle and job-related accidents, but also to
increased mortality from liver cirrhosis, stroke, and cancer.
“Binge drinking” means heavy consumption of alcohol within a
short period of time with the intention of becoming intoxicated.
Although there is no universally accepted definition for binge
drinking, usually consumption of five or more drinks by males
and four or more drinks by females is considered binge drinking.
The two major alcohol-related brain disorders are alcoholic
Korsakoff’s syndrome and alcoholic dementia. Korsakoff’s
syndrome is a brain disorder caused by a deficiency of thiamine
(vitamin B1), and major symptoms include severe memory loss,
false memory, lack of insight, poor conversation skills, and
apathy. Some heavy drinkers may also have a genetic
predisposition to developing this syndrome.
In Korsakoff’s syndrome, loss of neurons is a common feature,
including microbleeding in certain regions of gray matter.26 In
an alcoholic, when Wernicke’s encephalopathy appears along with
Korsakoff’s syndrome, it is called Wernicke-Korsakoff syndrome.
Wernicke’s encephalopathy and Korsakoff syndrome are two related
diseases, both caused by thiamine deficiency, but accompanying
clinical symptoms may be different. Alcoholics with Korsakoff
syndrome always have severe amnesic syndrome (severe memory
loss) but may not have classical symptoms of Wernicke’s
encephalopathy, which include ophthalmoplegia (paralysis or
severe weakness of one or more of the muscles that control eye
movement), ataxia (lack of coordination during voluntary muscle
movement, such as walking), and confusion. However, patients
with Wernicke-Korsakoff syndrome show most of the symptoms found
in both diseases. Alcoholics in general have a reduced brain
weight compared to nondrinkers.
In a ten-year follow-up study in Sweden of 5,769 adults (ages
thirty-five to seventy-five) without cardiovascular disease,
Foerster et al.
(2009) demonstrated that by increasing the amount of alcohol
consumption
to more than twenty-five drinks per week, blood pressure
increased
in heavy drinkers and all beneficial effects of alcohol
consumption disappeared.
In addition, wine drinking increased good cholesterol (highdensity
lipoprotein cholesterol or HDL), while drinking beer and spirits
resulted in increased concentrations of triglycerides. U.S.
physicians (2,970 diagnosed with diabetes mellitus), the authors
observed that weekly consumption of alcohol reduced the risk of
heart
disease by 33 percent, while daily consumption of alcohol
reduced the
risk by 58 percent among diabetics. For the nondiabetic, weekly
consumption
of alcohol reduced the risk of heart disease by 18 percent,
while daily
consumption of alcohol reduced the risk by 40 percent. The
protective
effect of alcohol against stroke was detected in both younger
and
older groups of men and women in all ethnic groups (white,
black, and
Hispanic). However, this protective effect against stroke
disappeared
in heavy drinkers (seven or more drinks per day), and such
chronic
consumption of alcohol increased the risk of having strokes by
approximately
three times that of nondrinkers.31 In a follow-up study, it was
demonstrated that moderate drinkers (up to two drinks per day)
had a 33
percent reduced risk of ischemic stroke (all ethnic groups, both
men and
women) compared to nondrinkers.
Moderate alcohol consumption can dramatically reduce the risk of
age-related dementia and developing Alzheimer’s disease. A
French study using 3,777 community residents ages sixty-five
years or older demonstrated that the subjects who drank three to
four glasses of alcoholic beverages (mostly wine) per day (318
subjects) had 82 percent lower risk of developing senile
dementia and 75 percent lower risk of getting Alzheimer’s
disease compared to nondrinkers (971 subjects). However, chronic
abusers of alcohol are at a higher risk of developing memory
loss, dementia, and lack of appropriate motor control due to
alcohol-related brain damage. Younger people, especially
underage drinkers, are also at higher risk of alcohol-related
brain damage. In the California Men’s Health Study using 84,170
men ages forty-five to sixty-nine, consumption of one or more
drinks per day was associated with approximately 60 percent
reduced lung cancer.
Irregular heavy drinking even once a month (five or more drinks
per occasion) increases the risk of heart disease rather than
protecting the heart as observed in moderate drinkers. Binge
drinking is also dangerous. In one study (based on a population
of 1,641 men who drank beer), the authors observed that the risk
of death in men who drank six or more bottles of beer in one
occasion was almost three times higher than those who consumed
less than three bottles in one occasion. Many investigators have
reported a close link between violent behavior, homicide, and
alcohol intoxication. Studies conducted on convicted murderers
suggest that about half of them were under the heavy influence
of alcohol at the time of the murder.
The liver is one of the largest and most complex organs of the
human body. It synthesizes important proteins vital for life,
stores some nutrients, and breaks down (metabolizes) drugs and
toxins, including alcohol, thus protecting the body from harmful
effects. Although the liver has an amazing capacity for
self-healing through regeneration, certain liver diseases, such
as cirrhosis of the liver, are irreversible and may even cause
death. Alcohol-induced liver disease can be classified under
three categories: (1) fatty liver; (2) alcoholic hepatitis; and
(3) liver cirrhosis.
Heavy drinking for as little as a few days may produce fatty
changes in the liver (steatosis), which can be reversed after
abstinence. However, drinking heavily for a longer period may
cause severer alcohol-related liver injuries, such as alcoholic
hepatitis and cirrhosis of the liver. The diagnosis of alcoholic
hepatitis is a serious medical condition because approximately
70 percent of such patients may progress to liver cirrhosis, a
major cause of death worldwide. However, if a patient with
alcoholic hepatitis practices complete abstinence, this
condition may be reversible. Diminished sexual function in
alcoholic men has been described for many years. Administration
of alcohol in healthy young male volunteers causes diminished
levels of testosterone. Even drinking three or more drinks a day
may cause significant problems in women, including delayed
ovula-tion or failure to ovulate and menstrual problems, but
such problems do not affect women who consume two or fewer
drinks a day. Approximately 2 to 4 percent of all cancer cases
may be linked to alcohol abuse. Epidemiological research has
demonstrated a dose-dependent relationship between consumption
of alcohol and certain types of cancers; as alcohol consumption
increases, so does the risk of cancer. The strongest link was
found between alcohol abuse and cancer of the mouth, pharynx,
larynx, and esophagus.