The 2.5 million Euro question: should wine be removed from the Mediterranean Diet?
The current review discusses the scientific debate about moderate consumption of wine/alcoholic beverages and provides the rationale for a large trial comprehensively assessing the clinical effects of wine/alcohol in the Mediterranean diet.
Moderate consumption of red wine represents one of the beneficial components of the traditional Mediterranean Diet (Med Diet). Many well-conducted epidemiological studies have shown that light to moderate intake of alcoholic beverages has been associated with a reduced risk of cardiovascular disease (CVD) but also of all-cause mortality.
The PREDIMEDThe PREDIMED study is one of the few randomized controlled trials about the Mediterranean Diet. More... study has provided the strongest evidence so far in clinical nutrition research supporting a causal inference between diet and cardiovascular disease. This randomized trial demonstrated the benefits of the Med Diet compared to a low-fat control diet showing a 30% reduction of CVD during a 5-year intervention.
The main tool for assessing the adherence to the Med Diet in the PREDIMEDThe PREDIMED study is one of the few randomized controlled trials about the Mediterranean Diet. More... trial was a 14 item Med Diet adherence questionnaire, which has also been used and validated in many different countries. One of these 14 item items is the consumption of 1 glass of wine daily. It has been shown that wine is the single most important item in this Mediterranean diet score. Thus, according to the available evidence, it can be concluded that the protective effect of the Med Diet against total mortality will be reduced between 12% and 24% when red wine consumption is removed.
On the other hand, modelling studies such as the Global Burden of Disease 2016 (GBD) study supported that the healthiest option would be to completely abstain from any alcoholic beverages. However, the conclusions of the GBD study changed four years later with the publication of the GBD 2020 report, where the results showed benefits of small amounts of alcoholic beverages in adults older than 40 years. Therefore, the GBD studies eventually recognized a “safe level” of alcohol intake.
The author of this review explains that studies supporting abstention may have missed important factors such as drinking pattern and smoking, which may distort the effects of alcohol on health. If smoking is not sufficiently controlled for, a flawed over-estimation of the alcohol-related harms may be a realistic assumption.
Furthermore, the GBD studies did not evaluate the drinking pattern. The focus was only on the absolute amount of alcohol intake. It is very likely that the drinking pattern will modify the effects of alcohol on the health outcomes considerably. The main features of drinking pattern that may modify the health outcomes of alcohol are:
- Moderate intake
- Spreading out the consumption throughout the week without concentrating it on 1-2 days of the week
- Avoidance of binge drinking
- Consumption with the meals instead of consuming it on an empty stomach
- Avoidance of distilled liquors
Following these Mediterranean alcohol drinking patterns may be a healthier approach to alcohol consumption or a harm reduction approach.
Because of the above-described limitations of studies and opposing positions, there is need for stronger sound evidence, which is a randomized controlled trial comprehensively addressing the clinical effects of alcohol. It should assess the effects of recommending moderate consumption compared to abstention.
The European Research Council funded the University of Navarra Alumni Trialist Initiative with 2.5 million euros to assess the health effects of alcohol through an advanced research grant.
During this 4-year trial, 10 000 Spanish drinkers (men 50-70 year and females 55-75 year) will be randomly assigned to receive repeatedly 2 different advices:
- Total abstention of any alcoholic beverages
- Moderate drinking (females ≤ 7 drinks/week and men ≤14 drinks/week)
- Together with avoidance of any binge drinking, preferred consumption of red wine with the meals and spread throughout the week.
Moderate consumption is hypothesized to be noninferior to abstention.
The primary outcomes will be all-cause mortality, cardiovascular events, cancer, chronic liver disease, type 2 diabetes, depression, dementia, injuries, and infection requiring hospital admissions. The author concludes that such trial will provide for the first time an evidence-based answer to a question of utmost interest in clinical medicine, given the opposing views in the scientific community on the most sensible advice for moderate drinkers.
