Heart Disease and Alcohol
By Hope Ricciotti, MD
New study finds frequency of drinking more important than amount
More and more research has confirmed the heart-health benefits of moderating drinking. A recent study from researchers at Beth Israel Deaconess Medical Center takes the alcohol and heart disease equation one step further by linking the heart benefits of alcohol to the frequency of drinking. According to this study, which was published in the New England Journal of Medicine (January 2003), the number of days a person drinks is more important than the amount of alcohol and type of alcoholic beverage on heart health.
A recent study of 38,000 men has shown that when it comes to heart disease, those who drink with greater frequency receive the greatest benefit. "Our study was consistent with other findings that have found moderate alcohol decreases heart disease risk. But this was the first long-term study that looked at beverage type and frequency of drinking. In this respect we broke some new ground," says lead researcher Dr. Kenneth Mukamal, internist for Beth Israel Deaconess Medical Center.
The men involved in this study were followed for a period of twelve years. Over that time, approximately 1400 of them had heart attacks or died of heart disease. To get a better understanding of how alcohol might have affected an individual's risk of heart disease, investigators surveyed all participants on how much alcohol, on average, they drank. It was found, as expected, that moderate drinkers had a lower risk of heart disease than non-drinkers, or even very light drinkers.
Participants were also surveyed to determine if drinking patterns and beverage type had any affect on a person's risk for heart disease. The data collected indicate that drinking patterns make a big difference in how alcohol affects the development of heart disease. Specifically, the results showed:
- Men who drank three to four days a week or more had the lowest risk of heart disease even when drinking relatively small amounts of alcohol.
- Men who drank five to seven days a week had a slightly lower risk than those who drank three to four days a week.
- Men who drank one to two days a week only had a 12% lower risk than non-drinkers.
Investigators also looked at beverage type. It was found that beverage type didn't really seem to make a difference when it came to heart health. Like most American men, the p
opulation of men studied commonly consumed beer and spirits. "Interestingly, the data showed that it was beer and spirits that were most strongly associated with lower heart disease risk," says Mukamal.
The fact that beer and spirits conferred the greatest benefit among the men in this study may seem surprising given the amount of media attention given to the heart benefits of wine. According to Mukamal, there has been a popular mythology that red wine offers some special benefit, but the results of this study do not support that thinking. Mukamal explains that he does not believe that wine is bad, it's just that in his study group wine was not commonly drunk.
"One would anticipate that if we did this same study in women, who tend to be wine drinkers, a reduced risk of heart disease might also be found among those who drank wine with greater frequency and consistency," suggests Mukamal.
Alcohol increases women's risk for breast cancer
When it comes to making assumptions about heart disease in women based on findings from studies of men, it may be advisable to tread cautiously. Actual research conducted on women has shown that gender differences can affect the pathophysiology, diagnosis and treatment of women with heart disease. In the case of alcohol consumption, studies on women have shown that women may confer a heart benefit but not without also incurring a greater risk for developing breast cancer.
The Nurses' Health Study, which has followed more than 237,000 women for nearly 30 years, has shown that more than two drinks a day increases the chance of developing breast cancer by 20- 25%. This does not mean that 20-25% of women who drink two drinks a day will develop breast cancer. Instead, two drinks increases the a woman's lifetime risk of developing breast cancer from 12 of every 100 women the average risk in this country to 14 or 15 out of every 100 women.
Folate found to decrease breast cancer risk
Studies have shown that the increased risk of breast cancer associated with alcohol is seen mostly in women who do not ingest enough of the B vitamin called folic acid. Alcohol is known to interfere with the body's absorption of folic acid and increase the excretion of the vitamin by the kidneys. It is not yet clear how folic acid works to prevent breast cancer.
"I would recommend that women who choose to drink should consider taking a multivitamin that contains folic acid as well. But, there is probably no safe level of alcohol that does not increase a woman's risk of breast cancer." says Mukamal.
Balancing the risk between heart disease and breast cancer
While heart disease is the number one killer of women, many would argue that premenopausal women are justified in their fear of breast cancer. Although the incidence of breast cancer increases with age, it spills over into younger and middle-aged women in a way that makes it a much more compelling concern. Breast cancer in older women is usually a slow growing disease, while in younger women it is more often fast growing.
"Heart disease is not uncommon in older women and so it is really sort of a balancing act trading off one risk against another," says Mukamal.
According to Mukamal, women should understand that the benefits of alcohol are probably not going to work in their favor until they are postmenopausal. At this time, women have a greater risk of dying from heart disease. Mukamal suggests that the risks associated with alcohol, including breast cancer, automobile accidents and fetal alcohol syndrome are going to be important considerations for younger women.
"Before then, I think that it is pretty clear for most people that nobody should think they are going to get any health benefits from drinking alcohol because the risks are substantial," says Mukamal.
How does alcohol affect breast cancer development?
It is not yet known exactly how alcohol affects breast cancer development. Alcohol may have some direct affects on the breast. Moderate levels of alcohol have been found to raise estrogen levels, which can contribute to breast cancer development. Low doses of alcohol have been associated with increasing bone density, which may be the result of alcohol's ability to increase estrogen levels in the body.
How does alcohol protect from heart disease?
There is very strong evidence that alcohol consumption raises "good" cholesterol. From other studies of good cholesterol it is thought that this explains about half the benefit of alcohol on heart disease. But there has been a great deal of speculation about where the remainder of the benefit arises. There have been some recent observational studies that have suggested that moderate drinkers have lower levels of C-reactive protein, which is a marker of inflammation, and high levels have been associated with heart disease. So, it possible that some of the affects of alcohol are through lowering of C-reactive protein, but there currently is not a lot of direct experimental proof.
There is better evidence that alcohol lowers levels of fibrinogen, which is a blood-clotting factor. Many believe that this blood thinning property of alcohol may account for the other half of alcohol's benefit. There is also some very intriguing evidence on alcohol's affect on blood sugar. The US Department of Agriculture conducted a study on a large group of postmenopausal women. In this study, women were randomized to two groups: half drank alcohol everyday and half drank a fake beverage that had no alcohol but that had a similar amount of calories everyday. The results showed that among women who drank alcohol everyday blood sugar levels and insulin levels dropped. This suggests that alcohol may improve our body's response to insulin. We know that insulin sensitivity is a very important marker for heart disease. Insulin resistance occurs when the body can't use insulin efficiently and can cause adult onset diabetes. Diabetes is a major risk factors for cardiovascular disease. In fact, adults with diabetes are two to four times more likely to have heart disease or suffer a stroke than adults without diabetes.
In summary, the role of alcohol in health maintenance for women is more complex than for men. While there is clear evidence that alcohol improves heart health, in young women, this benefit must be balanced with other risks including breast cancer and birth defects. Most authors agree that moderate alcohol consumption in the post-menopausal years is part of a total program of health that includes a healthy diet, regular exercise, and a daily multivitamin.
(Published March 2003)