Page last updated: August 7, 2015
Effects of alcohol on blood pressure in women: A randomized trial

The present paper describes the effects among 24 normotensive pre-menopausal women, all of whom were regular drinkers (of an average of 2 to 3 drinks/day), of the administration of two levels of alcohol in the form of red wine in a randomized clinical trial. Subjects were given low amounts of wine and higher amounts of wine during two 4-week intervention periods, with the effects on blood pressure compared with changes when subjects were given similar amounts of dealcoholized red wine.

Subjects were divided into a “lower level” usual intake group who previously consumed < 200 g/week of alcohol and a “higher level” group who previously consumed >200 g/week. Previous “lower level” drinkers were given two levels of alcohol, in the form of 100 ml/day of red wine on 4 days per week (an average of 46 g/week of alcohol, or the equivalent of about ½ typical drink per day) and 200 ml/day of red wine daily (about 146 g/week of alcohol, the equivalent of about 1 ½ to 2 typical drinks/day) for another 4-week period. Subjects who were previous “higher level” drinkers were given 100 ml of red wine daily (about 73 g/d of alcohol per week, the equivalent of about one typical drink/day) for 4 weeks and 300 ml/d of red wine (about 218 g/week of alcohol, the equivalent of about 2 to 3 typical drinks/day) for another 4 weeks.

The main results are a small but significant increase in 24-hour average blood pressure (+2.0 mmHg systolic and +1.3 mmHg diastolic) with higher levels of red wine but no significant effects (+0.4 mmHg systolic, -0.3 mmHg diastolic) from lower levels of red wine administration, when compared with blood pressure levels during periods when dealcoholized red wine was given. The differences were predominantly due to slightly higher awake rather than asleep blood pressures. These findings are similar to results of a limited number of randomized controlled trials of alcohol in men.

Forum members considered this to be a well-conducted clinical trial, with important results. There were, however, some concern that the study focused only on regular drinkers; results may have been different if previous abstainers had also been studied. Further, while the slight increase in blood pressure from higher levels of alcohol support previous research, the finding of no significant findings for lower levels of intake (when subjects were given the equivalent of between ½ and 1 drink/day) may not support what the authors suggest: “Our results provide no support for the concept that regular low-level alcohol intake can lower BP, suggesting that the J-shaped relationship between alcohol and BP in several studies is more likely because of the presence of unmeasured confounders.”

Forum members considered their results to be consistent with either a slight increase or a slight decrease in blood pressure among such drinkers and are not necessarily inconsistent with data from some previous cohort studies that showed a “J-shaped” relation between alcohol and blood pressure. A number of Forum reviewers also raised the question as to whether or not the results of a 4-week intervention study can be extended to the effects of the regular intake of alcohol for many years. Further, the fact that the study group included previous drinkers of up to similar amounts of alcohol as given during the higher intervention (yet were still normotensive) might suggest that their blood pressure was not “sensitive” to alcohol, and could limit the applicability of these results to the general public. Nevertheless, this intervention study provides important trial data on the short-term effects of alcohol on blood pressure.

Reference: Mori TA, Burke V, Beilin LJ, Puddey IB. Randomized Controlled Intervention of the Effects of Alcohol on Blood Pressure in Premenopausal Women. Hypertension 2015;66:00-00. DOI: 10.1161/HYPERTENSIONAHA. 115.05773

For the full critique of this paper by members of the International Scientific Forum on Alcohol Research, please click here.
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