What Is “Moderate” Alcohol Intake?
One drink is commonly defined as 12 ounces of beer, 5 ounces of wine, or 1.5 ounces of distilled spirits. For women the 2005 Dietary Guidelines for Americans define moderate drinking as no more than one drink per day.1 For men moderate drinking is defined as no more than two drinks per day.
Why should women drink less than men? For one thing women tend to weigh less than men and also tend to have proportionately less water in their bodies to disperse the alcohol; this means that a single drink will, on average, have a greater effect on a woman than on a man. Furthermore, some studies have suggested that women tend to have lower levels of an enzyme that breaks down alcohol (alcohol dehydrogenase) in their stomachs.2 This would also increase the amount of alcohol that reaches the blood stream.
Alcohol and Cancer
Worldwide an estimated 3.5 percent of all cancer deaths are attributable to alcohol.3 Links have been established between alcohol and several types of cancer, including cancers of the mouth, pharynx, larynx, esophagus, breast, colon and rectum, and liver.4 Risk of some of these cancers—such as cancer of the mouth—is particularly elevated in people who both smoke and drink.
The way in which alcohol contributes to cancer development is still uncertain and may vary by cancer type, but there are several possible explanations for the link. In the case of breast cancer, many researchers have speculated that alcohol increases risk by altering the levels of hormones such as estrogen.5 The risk of breast and other cancers may also be increased by potentially carcinogenic compounds such as acetaldehyde that are produced during alcohol metabolism (the processing of alcohol by the body). The extent to which drinkers are exposed to acetaldehyde may be influenced by inherited differences in genes involved in alcohol metabolism, and researchers are evaluating whether these genetic differences influence the risk of cancer in drinkers.6
Regardless of underlying explanation, it appears that even moderate drinking can increase the risk of cancer. In the case of breast cancer, each 10-gram (slightly less than one drink) increase in daily alcohol consumption increases the risk of breast cancer by an estimated 7 to 10 percent.7,8 Although this is a fairly modest increase in risk, breast cancer is a common cancer; even a small increase in risk may translate into many additional cases on a population level. Furthermore, as Dr. Colditz points out, alcohol is one of the few breast cancer risk factors that we can change.
The good news for those of us who enjoy the occasional drink, however, is that it may be possible to reduce alcohol’s effects on breast cancer risk. “Studies of dietary folate and, probably more importantly, blood levels of folate show that the adverse effect of alcohol on risk of breast cancer is really only limited to women who have low blood folate levels,” says Dr. Colditz. “Taking a multivitamin every day is sufficient to get beyond the low blood levels that would carry risk.”
Other Health Problems Linked with Alcohol Use
Cancer is certainly not the only health concern when it comes to alcohol. An estimated one-third of all traffic fatalities are linked with alcohol use, 9 and even low blood alcohol concentrations can impair driving ability.10 At higher levels of intake, alcohol increases the risk of high blood pressure and heart problems and may also increase the risk of hemorrhagic stroke (bleeding within the brain).11 High levels of alcohol also have adverse effects on the liver and the brain. An important point for women is that many of these adverse effects tend to develop earlier in women than in men and at a lower level of alcohol intake.12
Drinking during pregnancy can cause a range of problems in the child. Fetal alcohol syndrome is one of the most severe outcomes (other than fetal death) and is characterized by distinctive changes to the facial features, small size at birth, and damage to the brain.13 According to the U.S. Centers for Disease Control and Prevention, there is no known amount of alcohol use that is safe during pregnancy and no known time during pregnancy when alcohol use is safe.14
And, finally, alcohol use can lead to alcohol dependence (alcoholism) in some individuals. Women who have a family history of alcohol problems will need to be particularly careful about their use of alcohol and may wish to avoid it altogether.
Potential Health Benefits of Alcohol Use
The well-publicized link between moderate alcohol intake and a reduced risk of heart disease applies to both men and women.15 This is an important benefit because heart disease is the number one killer in the United States. Alcohol is not the only way to reduce your risk of heart disease, however. Engaging in regular physical activity, avoiding tobacco smoke, and eating a healthy diet (see Dietary Guidelines1) will reduce your risk even if you abstain from alcohol. It’s also important to realize that young women (those under the age of 40 or so) have a very low risk of heart disease and are therefore unlikely to derive a heart benefit from moderate alcohol intake. This means that in young women the risks of alcohol likely outweigh the benefits.15
Another measure of alcohol’s health effects is total mortality (risk of death from any cause). Numerous studies have reported that there is a “J-shaped” relationship between alcohol intake and risk of death: overall risk of death declines with light-to-moderate drinking but rises with heavier drinking.16
Do Health Effects Vary by Type of Alcohol?
Although many people view red wine as a healthier choice than other types of alcohol,17 different types of alcohol appear to have similar health effects. “The predominant evidence is that it’s total alcohol intake that increases the risk of breast cancer and increases the risk of colon cancer and at the same time decreases the risk of heart disease,” says Dr. Colditz. “The more detailed the studies are that look at this, the clearer it is that total alcohol is the active component rather than a product of grapes that you’ll find in red wine and not in other alcoholic beverages.”
How to Balance the Risks and the Benefits
For many women the decision about occasional use of alcohol will remain a personal one that’s best made in consultation with a physician. There are both risks and benefits, but the balance of risks and benefits varies by a woman’s health history and family history (including history of alcohol abuse), age, risk of conditions such as heart disease and breast cancer, and other medications she is taking. If you don’t currently drink, however, be reassured that there do not appear to be compelling reasons to start.
“One of the reasons for that,” says Dr. Colditz, “is that there is a subset of the population that has a predisposition to addictive behavior, so all the recommendations start with If you drink, drink in moderation, with the explicit purpose of not encouraging people to begin drinking if they aren’t already.” And for women who currently drink, Dr. Colditz notes, “I think we want to emphasize moderation and also emphasize, particularly for women, having adequate intake of folate to counter the adverse effect on breast cancer.”
1 Dietary Guidelines for Americans, 2005. US Department of Health and Human Services Web site. Available at:http://www.health.gov/dietaryguidelines/dga2005/document/default.htm. Accessed June 22, 2008.
2 Frezza M, di Padova C, Pozzato G, Terpin M, Baraona E, Lieber CS. High blood alcohol levels in women. The role of decreased gastric alcohol dehydrogenase activity and first-pass metabolism. New England Journal of Medicine. 1990;322(2):95-99.
3 Boffetta P, Hashibe M, La Vecchia C, Zatonski W, Rehm J. The burden of cancer attributable to alcohol drinking. International Journal of Cancer. 2006;119(4):884-87.
4 World Cancer Research Fund/American Institute for Cancer Research. Food, Nutrition, Physical Activity, and the Prevention of Cancer: A Global Perspective. Washington DC: AICR, 2007.
5 Rinaldi S, Peeters PH, Bezemer ID, et al. Relationship of alcohol intake and sex steroid concentrations in blood in pre- and post-menopausal women: The European Prospective Investigation into Cancer and Nutrition. Cancer Causes and Control. 2006;17(8):1033-43.
6 Terry MB, Gammon MD, Zhang FF, et al. ADH3 genotype, alcohol intake and breast cancer risk. Carcinogenesis. 2006;27(4):840-47.
7 Collaborative Group on Hormonal Factors in Breast Cancer. Alcohol, tobacco and breast cancer—collaborative reanalysis of individual data from 53 epidemiological studies, including 58,515 women with breast cancer and 95,067 without the disease. British Journal of Cancer. 2002;87(11):1234-45.
8 Key J, Hodgson S, Omar RZ, et al. Meta-analysis of studies of alcohol and breast cancer with consideration of the methodological issues. Cancer Causes & Control. 2006;17(6):759-70.
9 Traffic Safety Facts, 2006 Data: Alcohol-impaired Driving (HOT HS 810 801). National Highway Traffic Safety Administration Web site. Available at:http://www-nrd.nhtsa.dot.gov/Pubs/810801.PDF. Accessed June 22, 2008.
10 Hingson R, Winter M. Epidemiology and consequences of drinking and driving. Alcohol Research and Health. 2003;27(1):63-78.
11 Kloner RA, Rezkalla SH. To drink or not to drink? That is the question. Circulation. 2007;116(11):1306-17.
12 Alcohol: A Woman’s Health Issue (NIH Publication No. 04-4956). National Institute on Alcohol Abuse and Alcoholism Web site. Available at:http://pubs.niaaa.nih.gov/publications/brochurewomen/women.htm. Accessed June 23, 2008.
15 Hanksinson SE, Colditz GA, Manson JE, Speizer FE, eds. Healthy Women, Healthy Lives: A Guide to Preventing Disease from the Landmark Nurses’ Health Study. New York: Simon & Schuster Source; 2001.
16 Di Castelnuovo A, Costanzo S, Bagnardi V, Donati MB, Iacoviello L, de Gaetano G. Alcohol dosing and total mortality in men and women: An updated meta-analysis of 34 prospective studies. Archives of Internal Medicine. 2006;166(22):2437-45.
17 Wright CA, Bruhn CM, Heymann H, Bamforth CW. Beer and wine consumers’ perceptions of the nutritional value of alcoholic and nonalcoholic beverages. Journal of Food Science. 2008;73(1):H8-11.
18 Centers for Disease Control and Prevention (CDC). National Center for Health Statistics, National Health Interview Survey, 1997-2006. Data on alcohol consumption available at:http://www.niaaa.nih.gov/Resources/DatabaseResources/QuickFacts/AlcoholConsumption/dkpat25.htm (Accessed April 29, 2008).
Tags: Nutritional Know-How