The whole issue of whether drinking a glass or two of wine a day is good or bad for you has raged in the health community for years. One study seems to say one thing, then another comes out and is contradictory. Some researchers have dismissed some studies because drink companies have fully or partially funded them, though in many cases there observations are perfectly valid. In the face of this ambiguity, some health bodies have advocated strict and low limits on weekly drinking e.g. UK 14 units per week in both men and women.
For years, moderate drinking was linked to many health benefits, including a lowered risk of developing heart disease and longer life expectancy. But more recently, these assumptions were been called into question by a 2016 meta-analysis of 87 long-term studies which concluded that many of these health benefits could be explained by apparent flaws in study design. Some studies compared moderate drinkers to current abstainers, this "sick quitter" group included former heavy drinkers and those who were tee-totallers because of health conditions. After correcting for these factors, the study’s authors found no evidence that moderate drinking had protective health benefits in most groups.
However, the study was criticised because the number of studies with design flaws was relatively low and trying to extrapolotate data from this relatively low number of sick quitters was like trying to slice a tiny piece of salami with a blunt knife.
So it was concluded in the health community that more analysis is needed on the long term effects of alcohol consumption and health and in the meantime they advocated caution especially as alcohol is linked with raising the risk of some cancers e.g. breast (relative risk higher by 8%, but moderate exercise reduces relative risk by 15%). Doesn't sound like too much fun.
In mid-August 2017, a new and large study was published in the Journal of the American College of Cardiology, "Relationship of Alcohol Consumption to All-Cause, Cardiovascular, and Cancer-Related Mortality in U.S. Adults" by Bo Xi, Sreenivas P. et al.
The study in 333,247 people found that light-to-moderate drinkers (less than 14 drinks in men and 7 drinks in women) did have a lower risk of dying from cardiovascular disease.
Individuals were followed between 1997 and 2009 and around 34,000 died sometime during this period. Throughout the length of the study, 34,754 participants died from all-causes. Of these, 8,947 deaths were cardiovascular disease-specific (6,944 heart disease-related and 2,003 cerebrovascular-related deaths) and 8,427 mortalities were cancer-specific.
The results of the study showed that men and women who were moderate drinkers had a 13 percent and 25 percent decreased risk of all-cause mortality, and 21 and 34 percent decreased risk of cardiovascular disease mortality, respectively.
Men who are heavy drinkers have a 25 percent increased risk of mortality due to all-causes and a 67 percent increase in mortality from cancer; however, these results were not significant in women. There were similar findings for light drinking for both men and women.
This is the key point. Bo Xi and his team were careful to address the supposed flaws in previous studies on alcohol and health. So the non-drinker group only included lifetime nondrinkers, so "sick quitters", former heavy drinkers and those who gave up alcohol because they got sick were excluded.
The paper also controls for smoking, Body Mass Index (BMI) and physical activity, Some academics still believe that total lifetime abstainers are rare and could share other, unforeseen traits that impact their health, whereas moderate drinkers might have an overall healthier lifestyle. Causation is almost impossible to identify and this will always be a flaw.
But this new observational study tries its hardest to be large, well designed and lasted for 12 years.
Dr. Sreenivas Veeranki, one of the study’s authors said “Our conclusions definitively show there is a J relationship” between drinking and heart health(as alcohol consumption goes up, at first the risk of dying from cardiovascular disease decreases slightly—the bottom of the J—before increasing once intake exceeds around 10 drinks per week) The curve illustrates “moderate drinking has a protective effect, while heavy drinking or binge drinking is harmful.”
The authors concluded "Light and moderate alcohol intake might have a protective effect on all-cause and CVD-specific mortality in U.S. adults. Heavy or binge drinking was associated with increased risk of all-cause and cancer-specific mortality."
Link to full paper
Clinical paper abstract
Am Coll Cardiol. 2017 Aug 22;70(8):913-922. doi: 10.1016/j.jacc.2017.06.054.
Xi B, Veeranki SP, Zhao M, Ma C, Yan Y, Mi J.
Previous studies have revealed inconsistent findings regarding the association of light to moderate alcohol consumption with cardiovascular disease (CVD) and cancer mortality.
The aim of this study was to examine the association between alcohol consumption and risk of mortality from all causes, cancer, and CVD in U.S. adults.
Data were obtained by linking 13 waves of the National Health Interview Surveys (1997 to 2009) to the National Death Index records through December 31, 2011. A total of 333,247 participants ≥18 years of age were included. Self-reported alcohol consumptionpatterns were categorized into 6 groups: lifetime abstainers; lifetime infrequent drinkers; former drinkers; and current light, moderate, or heavy drinkers. Secondary exposure included participants' binge-drinking status. The main outcome was all-cause, cancer, or CVD mortality.
After a median follow-up of 8.2 years (2.7 million person-years), 34,754 participants died of all causes (including 8,947 CVD deaths and 8,427 cancer deaths). Compared with lifetime abstainers, those who were light or moderate alcohol consumers were at a reduced risk of mortality for all causes (light-hazard ratio [HR]: 0.79; 95% confidence interval [CI]: 0.76 to 0.82; moderate-HR: 0.78; 95% CI: 0.74 to 0.82) and CVD (light-HR: 0.74; 95% CI: 0.69 to 0.80; moderate-HR: 0.71; 95% CI: 0.64 to 0.78), respectively. In contrast, there was a significantly increased risk of mortality for all causes (HR: 1.11; 95% CI: 1.04 to 1.19) and cancer (HR: 1.27; 95% CI: 1.13 to 1.42) in adultswith heavy alcohol consumption. Binge drinking ≥1 d/week was also associated with an increased risk of mortality for all causes (HR: 1.13; 95% CI: 1.04 to 1.23) and cancer (HR: 1.22; 95% CI: 1.05 to 1.41).
Light and moderate alcohol intake might have a protective effect on all-cause and CVD-specific mortality in U.S. adults. Heavy or binge drinking was associated with increased risk of all-cause and cancer-specific mortality.
The press release from the American College of Cardiology
Men and women who engage in light-to-moderate alcohol consumption have a decreased risk of mortality from all-causes and cardiovascular disease, according to a study published August 14 in the Journal of the American College of Cardiology.
Bo Xi, MD, et al., looked at the relationship between all-cause, cardiovascular disease and cancer mortality risks and current alcohol consumption patterns. The researchers used data from 333,247 participants obtained through the National Health Interview Surveys from 1997 to 2009. Alcohol consumption patterns were divided into six categories: lifetime abstainers, lifetime infrequent drinkers, former drinkers, and current light (less than three drinks per week), moderate (more than three drinks per week to less than 14 drinks per week for men or less than seven drinks per week for women) or heavy drinkers (more than 14 drinks per week for men or seven drinks per week for women).
Throughout the length of the study, 34,754 participants died from all-causes. Of these, 8,947 deaths were cardiovascular disease-specific (6,944 heart disease-related and 2,003 cerebrovascular-related deaths) and 8,427 mortalities were cancer-specific.
The results of the study showed that men who are heavy drinkers have a 25 percent increased risk of mortality due to all-causes and a 67 percent increase in mortality from cancer; however, these results were not significant in women. Men and women who engaged in moderate drinking had a 13 percent and 25 percent decreased risk of all-cause mortality, and 21 and 34 percent decreased risk of cardiovascular disease mortality, respectively. There were similar findings for light drinking for both men and women.
Light-to-moderate drinking may have protective factors for either all-cause or cardiovascular disease mortality, write the authors. To decrease all-cause, cardiovascular disease and cancer mortality risks, the researchers emphasize that a balance needs to be considered when looking at individual patient recommendations, however reducing high alcohol consumption is necessary.
In an accompanying editorial, Giovanni de Gaetano, MD, PhD, said that while younger adults should not expect considerable benefit from moderate drinking, "for most older persons, the overall benefits of light drinking, especially the reduced cardiovascular disease risk, clearly outweigh possible cancer risk." He concluded by noting that those who do not drink should not start, but rather focus on adopting a healthy lifestyle surrounding "regular physical activity, no smoking, weight control and dietary habits."