Faculty Peer Reviewed
Alcoholic beverages have been part of human culture for thousands of years and cross nearly every political and demographic boundary. Despite this long history, the interaction between alcohol and human health is still poorly understood. This confusion is particularly true with regard to blood pressure, as multiple studies have debated the association between alcohol intake and the development or management of hypertension. For this discussion, in America a standard drink is defined as 12 ounces of regular beer, 5 ounces of table wine, or 1.5 ounces of hard liquor (a standard shot size) [i].
Most medical data on the effects of alcohol come from large observational studies and thus are inherently less definitive than interventional studies. However, a meta-analysis of 15 randomized controlled trials in which alcohol reduction was the only intervention between active and control groups found that alcoholic beverage reduction lowered systolic and diastolic blood pressure, with a dose-response relationship [ii]. Additionally, an older, randomized controlled crossover trial found that after an alcohol-reduction-induced drop in blood pressure, the resumption of baseline alcohol intake increased blood pressure back to pre-study levels [iii]. Taken together, these two studies implicate alcoholic consumption as a reversible cause of blood pressure elevation.
This effect correlates with many large studies that have consistently found that persons reporting usual daily intake of 3 drinks or more have a higher than average blood pressure. The association between chronic high-dose alcohol intake and blood pressure elevation has been shown in both genders, multiple racial and ethnic groups, disparate international populations, and across all adult age groups [iv]. However, the association between hypertension and light-to-moderate drinking–up to 2 drinks per day for men and 1 drink per day for women–is more complicated. Observational studies have provided inconsistent results, with light alcohol consumption associated with increased, decreased, or unchanged risk of hypertension development. A study of 66 510 examinees found that among women (but not men) reporting less than daily drinking, there was lower hypertension prevalence compared with abstainers [v]. This gender discrepancy was also seen in a study of 28 848 women followed prospectively in the Women’s Health Study and 13 455 men from the Physicians’ Health Study for an average of 10.9 and 21.8 years, respectively. This large study showed that light-to-moderate drinking was associated with reduced hypertension risk in women and increased hypertension risk in men [vi]. Racial considerations further complicate the light-drinking-hypertension picture. Relative to abstinence, black men consuming low-to-moderate amounts of alcohol appear to have a higher risk of hypertension compared to black women or Caucasians of either gender [vii]. Moreover, for men at any level of alcohol consumption, the risk of developing hypertension may be higher in Asian populations than non-Asian populations [viii].
On the other hand, a 20-year follow-up study of young adults revealed no association between baseline alcohol consumption and incident hypertension, except among European-American women, in whom any current alcohol consumption was associated with lower incident hypertension risk [ix].
Generally, this study found that exercise and smoking increased with increased drinking while, conversely, obesity and family history of hypertension tended to decrease with increased drinking status. Additionally, light and moderate drinkers had the highest proportions of college and graduate degrees and the lowest proportions of annual incomes less than $50,000 and difficulty paying for basics and medical care. Thus, socioeconomic factors may confound the data from the relatively high socioeconomic demographic populations in the Women’s Health Study and Physicians’ Health Study .
Popular culture, on the other hand, typically attributes these conflicting results to discrepancies between varieties of alcohol. In particular, red wine is often promoted as beneficial for cardiovascular health and blood pressure. However, multiple studies have refuted this claimed health disparity between alcohol categories. In particular, a well-designed crossover study of healthy men showed that daily consumption of greater than 3 alcoholic drinks as either red wine or beer for 4 weeks resulted in similar increases in systolic blood pressure and heart rate, while de-alcoholized red wine was no different than abstinence with regard to blood pressure [x]. This finding implies that ethanol itself is the chemical responsible for blood pressure elevation, regardless of the beverage.
The hypertensive effect of alcohol truly matters for population health, since alcohol-induced hypertension may be the most prevalent form of secondary hypertension. In fact, a recent study attributed alcohol as the cause of hypertension in 34.5% of men and 2.6% of women in a Japanese population [xi]. However, once hypertension develops, it appears the risks of hypertension are independent of the level of alcohol intake. A study that examined risk of cardiovascular sequelae separately in heavy drinkers, light drinkers, and abstainers found that all negative outcomes were progressively higher for increasing blood pressure categories across all alcohol consumption categories [xii].On the other hand, the general cardioprotective effects of alcohol are seen even in the presence of hypertension, as light drinkers have the lowest overall and cardiovascular mortality compared to drinkers in the higher alcohol consumption categories [xiii].
So what does this mean for an individual?
A patient with hypertension who is a moderate or heavy drinker should be strongly encouraged to cut back on his or her alcohol intake in an effort to better control hypertension. This may be particularly true for black and Asian men. Importantly, past drinkers do not seem to have higher hypertension prevalence, and this is true even for past heavy drinkers . This suggests that hypertension associated with alcohol drinking may be reversible with abstinence. However, some alcohol intake, especially among Caucasian women, seems to be beneficial for overall health. Thus, light drinking of any type of alcohol should not be discouraged, except among people who have a contraindication for alcohol use such as pregnancy, cirrhotic liver, or a history of alcoholism. One confounding factor is that substantially more binge drinking episodes occur among men at lower levels of average consumption, and such episodes are related to increases in hypertension incidence and risk [xiv]. In particular, light-to-moderate drinkers have higher mortality risks when they report heavy drinking occasions (defined by either eight drinks per occasion or getting drunk at least monthly). Consequently, episodic heavy drinking should be discouraged even with low-to-moderate total alcohol exposure . Finally, alcohol use can have major non-cardiovascular adverse consequences, including breast cancer, gastrointestinal cancer, oral cavity and pharyngeal cancer, esophageal and larynx cancer, hepatocellular cancer, pancreatitis, osteoporosis, violence, and suicide [xv]. Thus, it is not necessarily appropriate for medical professionals to encourage alcohol use. Yet overall, and even with comorbid hypertension, having one drink per week or maybe even one drink per day may actually improve mortality rates.
Benjamin Kenigsberg is a 3rd year medical student at NYU School of Medicine
Peer reviewed by Joseph Ravenell, MD, MS Assistant Professor Medicine, Division of General Internal Medicine, NYU Langone Medical Center
Image courtesy of Wikimedia Commons
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