Excerpt from Healthy Women, Healthy Lives
Excerpt from Healthy Women,
by Susan E. Hankinson, R.N., Sc.D., Graham
A. Colditz, M.D., JoAnn E. Manson, M.D., and
Frank E. Speizer, M.D.
Alcohol has been used by humans for at least
4,000 years and occupies a unique place in
most societies. It is often a sacred part of
religious ceremony and is a focal point of
many social celebrations and everyday interactions.
Yet it is an addictive drug that, when abused,
has potentially severe short-term and long-term
health consequences. These consequences depend
largely on how much a person drinks-and on
how much he/she can tolerate physiologically.
Alcohol tends to be less well tolerated by
women's bodies than men's, and thus the effects
can be more dramatic among women. A central
nervous system depressant, alcohol acts like
a sedative or tranquilizer, slowing down motor
coordination and reaction time. It also impairs
judgment, memory, reasoning, and self-control.
Drink for drink, women accumulate more alcohol
in their bloodstream than men and so experience
these effects much more rapidly. This is due
to several physiologic differences between
men and women. First, in order for alcohol
to be moved out of the bloodstream, it must
be neutralized by a certain enzyme in the stomach.
Women inherently have lower levels of this
enzyme than men. Second, women tend to have
a higher proportion of body fat than men, and
body fat does not absorb alcohol; it allows
alcohol to accumulate in the bloodstream. Finally,
despite having more body fat, women tend to
have smaller bodies than men. As a result,
they have less blood circulating in their bodies,
so that the ratio of alcohol to blood rises
much more rapidly than it does in men.
The other factor obviously influencing the
health consequences of alcohol is how much
is consumed. A committee of the Institute of
Medicine has defined three levels of alcohol
intake based on their health consequences:
low, moderate, and heavy. For women, low alcohol
intake means drinking less than half a drink
a day, with a drink defined as a 12-ounce bottle
of beer, a 5-ounce glass of wine, or a 1.5-ounce
shot of 80-proof liquor. This is about what
the average American woman drinks (that is,
two to three drinks a week) and is still considered
a relatively safe amount. Moderate drinking
is the next step up and involves having up
to two drinks a day. Though considered safe
in the short term, moderate drinking comes
with both risks and benefits in the long term.
Heavy drinking, on the other hand, has no benefits.
It can lead to cirrhosis, alcoholism, accidents,
violence, and a number of different cancers.
In this chapter, we examine the risks and benefits
of moderate drinking, where, unlike low and
heavy intake, the line is not always clear
in terms of safe versus unsafe.
The Benefits of Moderate Alcohol Consumption
Lower Risk of Coronary Heart Disease
Thanks to extensive media coverage, most women
now recognize that moderate alcohol consumption
can lower the risk of coronary heart disease.
Although red wine was initially thought to
be the most beneficial type of alcohol, it
is now apparent that beer, white wine, and
liquor also offer protection. In the Nurses'
Health Study, we found that drinking one drink
a day-be it a glass of wine, bottle of beer,
or shot of liquor-cut women's risk of coronary
heart disease by about half (see Figure 20-1).
Similar results have been reported in numerous
One of the questions that remains about this
relationship is whether women can receive the
same benefit by drinking two drinks on three
days of the week as by drinking one drink on
each day of the week. Few studies have looked
at this, but those that have have suggested
that the answer is no. In one large study,
researchers looked at the number of drinks
women consumed per day and the number of days
they drank per week. The lowest risk was seen
among women who drank one to two drinks per
day on five to six days per week. Those who
averaged the same number of drinks per week
but consumed them on fewer days had either
less benefit or none at all.
The reason for this is that the effects of
alcohol on the cardiovascular system are thought
to be only temporary. For example, alcohol
may increase the level of "good cholesterol" in
the blood and lower the level of a blood-clotting
substance, but only for about twenty-four hours.
By drinking a small amount of alcohol each
day, a woman may keep these substances in the
blood at the optimal level for protection against
Lower Risk of Ischemic Stroke
Given that ischemic stroke is similar in nature
to coronary heart disease (both being caused
by clogged blood vessels), it is not surprising
that alcohol has the same effect on ischemic
stroke that it does on heart disease. When
consumed in moderate amounts, alcohol can substantially
reduce the risk of both conditions. In the
Nurses' Health Study, we found that the risk
of ischemic stroke was about 50 percent lower
among women who drank one drink a day compared
to those who did not drink at all (see Figure
20-2). These results have been replicated in
many other large studies.
The Risks of Moderate Alcohol Consumption
Increased Risk of Breast Cancer
Alcohol is one of the most consistent dietary
factors related to the risk of breast cancer.
More than twenty-five studies have shown that
it increases risk, most likely by raising the
level of estrogen in the bloodstream or making
the breast more vulnerable to carcinogens.
In the Nurses' Health Study, we found that
the type of alcohol consumed was not as important
as the amount consumed. Women who drank half
a drink a day-be it beer, wine, or liquor-had
a slightly elevated risk of breast cancer,
while those who drank a whole drink a day had
an even higher risk. When researchers combined
our data with those from other large studies,
they found similar results: a woman's risk
of breast cancer rose by about 10 percent for
every additional drink she consumed per day.
In other words, a woman who averaged two drinks
a day had a 10 percent greater chance of developing
breast cancer than a woman who averaged one
drink a day. This was true regardless of the
type of alcohol consumed.
Because breast tissue may be particularly
vulnerable during adolescence and early adulthood,
researchers have speculated that drinking alcohol
during these time periods might be more harmful
than drinking alcohol later in life. To date,
studies on this topic have been inconsistent.
Increased Risk of Hip Fracture
Hip fractures become increasingly common as
women age. Prior to menopause, the body produces
enough estrogen to keep bones healthy and strong.
However, after menopause, estrogen levels drop,
and bones can become brittle and vulnerable
to fracture. About 90 percent of all hip fractures
occur in those over the age of sixty-five,
and most are the result of a bad fall.
Although alcohol increases estrogen levels
in postmenopausal women, and moderate alcohol
consumption has been linked to higher bone
mass, it is more likely that alcohol actually
leads to fractures. Drinking alcohol, even
in moderate amounts, can make a person less
steady and increase the likelihood that they
will fall and injure themselves. In the Nurses'
Health Study, we found that women who consumed
about a drink a day were twice as likely to
fracture their hips as women who did not drink
at all. Similar results have been reported
in several other studies, including the Framingham
Probable Increased Risk of Colon Cancer
Only a handful of long-term studies have examined
the relationship between moderate alcohol consumption
and the risk of colon cancer. To date, results
have been inconsistent. Several studies have
shown that alcohol does not alter colon cancer
risk, while others have demonstrated a modest
increase in risk. Overall, the epidemiologic
evidence suggests that alcohol probably does
increase the risk of colon cancer. This may
be because alcohol lowers the level of folate
in the body, which may in turn influence the
risk of colon cancer.
Probable Increased Risk of Hemorrhagic Stroke
Hemorrhagic stroke is much less common than
ischemic stroke but tends to be more severe.
It occurs when a small blood vessel in the
brain ruptures, causing bleeding (hemorrhaging)
into or around the brain. Although every stroke
is serious, brain hemorrhages are often devastating
because they can affect younger people and
are more likely to cause death.
It has been suggested but not confirmed that
moderate alcohol consumption might increase
the risk of hemorrhagic stroke. In the Nurses'
Health Study, we found a doubling of risk among
women who drank even small amounts of alcohol
each day. However, few studies have confirmed
If alcohol does in fact have an effect on
the risk of hemorrhagic stroke, it is most
likely indirect. Alcohol can raise a woman's
blood pressure, enhance blood flow to her brain,
and increase the chance of having irregular
heartbeats, all of which make it more likely
that a blood vessel in the brain will burst
and bleed. In addition, high levels of alcohol
intake have been shown to increase the tendency
How Alcohol Use Affects Length of Life
Drinking in moderation can decrease a
woman's risk of dying from some diseases, but increase her
risk of dying from others. The best evidence
of this to date comes from the American Cancer
Society Cancer Prevention Study II. In that
study, women who drank in moderation were about
20 percent less likely to die during the nine-year
study period than women who did not drink at
all. When researchers looked at specific causes
of death, they found that moderate drinkers
were much less likely than nondrinkers to die
of coronary heart disease and stroke. However,
moderate drinkers were also more likely to
die of breast cancer. Results in the Nurses'
Health Study were similar. Overall, these findings
suggest that while moderate drinking does confer
an overall mortality benefit-and a great benefit
in terms of heart disease-women must still
consider the increased risk of breast cancer
and possibly other cancers.
WHAT IT ALL MEANS
Alcohol can have a wide range of effects on
your health, depending on how much you consume.
If you drink heavily (two or more drinks a
day), you are at increased risk of cancer,
heart disease, alcoholism, cirrhosis, and fatal
accidents. This type of drinking has no benefits
and is not recommended for women at any age.
Moderate drinking, on the other hand, does
have some benefits, although it too has risks.
If you drink one drink a day, you receive some
protection against heart disease and ischemic
stroke. However, you are also at increased
risk of breast cancer, hip fracture, and probably
colon cancer and hemorrhagic stroke. These
risks and benefits are the same whether you
drink beer, wine, or liquor.