Healthy Drinking Habits

Summarized by Robert W. Griffith, MD
July 3, 2006

Summary

A Danish study shows that the risk of heart disease is lower in men who drink daily, and in women who drink once a week.

Introduction

There have been plenty of studies that show that a little alcohol, in moderation, is better for your health than no alcohol at all, or heavy consumption (see links below). Most of the evidence comes from studies in men, but relatively little is known about drinking patterns and the risk of heart disease in women. This is remedied by a recent Danish study reported in the British Medical Journal, which we summarize here.

What was done

Over 50,000 men and women living in Denmark were studied; they were enrolled in a national health study between 1993 and 1997; follow-up of the participants continued until 2002. At enrollment, data were obtained on alcohol intake and drinking frequency during the previous 12 months, and the subjects were then followed for an average of 5½ years.

Total alcohol intake was converted into the number of standard drinks containing 12 grams of ethyl alcohol. Frequency of drinking was categorized: never, less than once a month, 1-3 times monthly, once a week, 2-4 times weekly, 5 or 6 times weekly, and daily.

All coronary artery events (heart attack, severe angina, and sudden cardiac death) during follow-up were recorded, along with information on age, smoking habits, educational level, diet, and physical activity.

What was found

There were 28,400 women and 25,000 men in the study; they were middle-aged. Women drank on average 5.5 drinks a week, and men drank 11.3 drinks a week. The total number of drinks taken corrersponded closely with the frequency of drinking, in both men and women. During the 5½-year follow-up 749 women and 1283 men developed coronary heart disease (i.e. had a coronary artery event).

The risks ('hazard ratios') for having a coronary artery event, after adjustment for age, smoking, education, activity, BMI, and diet, were lessened in those who drank one drink a week or more, as shown in the table:

	'rarely'*	1 a week	2-4 a week	5 or 6 a week	daily
Women	100%	64%	63%	79%	65%
Men	100%	93%	78%	71%	59%

* rarely means never or less than 1 drink a week, scored as 100%
Using the 'rarely' group as the ones for comparison, it can be seen that for women, any drinking once a week or more often provided some protection - the risk was reduced to around 65%, meaning that for every 100 women who drank rarely and had an event, there were only 65 such events among those who drank more often.

Things were different in the men. For them, there was a "dose-dependent" reduction in risk with drinking. Thus men who drank on only one day a week had 93% risk, while those drinking daily had a 59% risk, compared with those drinking rarely.

What these findings signify

Women who drank alcohol on at least one day a week had a lower risk of coronary heart disease than women who drank less often. On the other hand, men who drank every day had a lower risk of coronary heart disease than those who drank less often - the more often they drank (up to 7 days a week), the lower the risk.

There was a serious limitation to the findings in this study; only 35% of those invited to participate actually did so. It's quite possible that those who took part were different from those who decided not to, although the overall frequency of coronary heart disease was the same in the participants as in the Danish population.

Why may there be a difference between women and men? It's possible that men who drink frequently are more likely to drink with meals, which may contribute to greater risk reduction, so that a 'dose-dependency' is seen; women, who don't drink so often with meals, don't show this change in beneficial effect with frequency. The other possible reason for a gender difference in results would be differing pharmacokinetics; this means that the hormones involved in breaking down alcohol differ in the sexes, leading to different amounts of breakdown products available at various times after consumption. Further, moderate alcohol intake increases estrogen levels, which, in women, provide a degree of protection against coronary heart disease before the menopause.

This study, as well as others showing beneficial effects of mild to moderate alcohol intake, must not be allowed to overshadow the ill-effects of heavy alcohol use - liver disease, increased cancer risk, road accidents, broken homes. As the investigators point out, "overall mortality is higher among individuals with a high alcohol intake compared with light consumers."

Source

• Prospective study of alcohol drinking patterns and coronary heart disease in women and men. J. Tolstrup, MK. Jensen, A. Tjonneland,  et al., BMJ, 2006, vol. 332, pp. 1244--1247

Related Links
Drinking Habits and Risk of Heart Disease
Cause for a (Small) Celebration?
Another Look at Alcohol and Stroke

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