Alcohol - the weight of evidence on health benefits

Early studies show benefits from alcohol

Studies were flawed

Alcohol is harmful

Other cautions

References

Early studies show benefits from alcohol

Until September 2015 this page concluded that moderate alcohol consumption has a number of health benefits, based on the conclusions of a number of studies. They suggested that older adults who enjoy a daily glass (one if you're a woman, two if you're a man) of an alcoholic beverage (wine, beer, or cocktails) are significantly less likely to develop coronary heart disease, stroke, age-related cognitive decline or dementia as the years go by.

These studies found that wine (1, 11) and alcohol (2) were beneficial for heart disease. Those who drank one to two glasses of alcohol three to four times a week had a lower risk of heart attack. (3) As recently as 2009 a meta study (8) or review of the research over many years, concluded that long-term moderate, non-binge regular consumption of alcohol provides significant health and longevity benefits to older people, compared to those who don't drink alcohol. The researchers suggest that moderate daily alcohol consumption promotes several anti-inflammatory processes. In particular, it protects against several harmful inflammation-inducing proteins in the brain. Other findings suggest that moderate drinking can boost cerebral blood flow by dilating vessels in the brain, protecting against cognitive decline including Alzheimer's disease. They suggest that these benefits accumulate over many years.

There are other beneficial compounds in many alcoholic drinks. Grape wine contains an antioxidant and anti-inflammatory called resveratrol. It protects against heart disease (11), cancer and many other diseases. It comes from the stems, leaves and skins of grapes, and is significantly higher in red wine as opposed to white, because the fruit sits in the wine for a longer period. High quality wines have higher levels than cheap plonk. One or two glasses of red wine per day seem to provide good antioxidant protection.

Note: raw grape juice contains about a third as much resveratrol as a red wine. However, it is not recommended because it contains a high level of fructose, which causes obesity and fructose malabsorption.

Other antioxidants are also found in wine and beer. Fermenting yeasts produce some antioxidants, as do the malt and hops used in beer.

In spite of those studies, I suggested that one to two glasses per day is too much and would prefer to follow the French tradition of having half a glass of wine with a meal.

Studies were flawed

A 2006 investigation (4) provided the first indication that earlier studies showing the benefits of alcohol may be flawed, after looking at how they were designed. The problem was that abstainers in these studies included people who had cut back or stopped drinking because of ill health or old age. This made the abstainers look like a less healthy group than they really were.

A 2015 study (7) showed that when you simply compare alcohol consumption and health outcomes, you find an apparent beneficial effect of moderate alcohol consumption. But when former drinkers are removed from the abstainers group, then the benefits disappear.

Alcohol is harmful

A 2014 World Health Organisation report on alcohol (5) is damning in its conclusions. In total, there are over 200 diseases and injuries that can be linked to alcohol consumption, including 30 that are caused only by alcohol. They include depression and anxiety, liver cirrhosis, pancreatitis, suicide, violence and accidental injury.

Alcohol is linked to cancers of the mouth, larynx, oesophagus, colon, liver, nose and breast cancer in women. Between 4% and 30% of cancer deaths worldwide can be attributed to alcohol use. Just one glass of alcohol per day increases the risk of breast cancer by 4%, average consumption increases the risk by 8%, and heavy drinking can increase breast cancer risk by 40-50%. Heavy drinking also weakens the immune system and is therefore associated with pneumonia, tuberculosis and other infections. Drinking encourages risky sexual behaviour which increases the chance of acquiring sexually transmitted infections such as HIV. Drinking during pregnancy is always harmful to the foetus (see below).

Another 2012 review of alcohol concluded that the evidence for the harmful effects of alcohol is undoubtedly stronger than the evidence for beneficial effects. (6)

People who regularly drink alcohol find it very difficult to lose weight, particularly a large gut and heavy midsection.

A study published in the journal Nature in 2017 found a possible explanation for the link between alcohol consumption and increased risk of cancer. Acetaldehyde is produced as a by-product of the metabolisation of alcohol, and it was shown to damage DNA and chromosomes. (9)

Most Caucasians have two groups of enzymes that protect against the effects of alcohol and the subsequent acetaldehyde. However, some races are deficient in these enzymes. For example, approximately 50% of East Asians have the cytosolic isozyme but not the mitochondrial isozyme. This may account for a substantially higher frequency of acute alcohol intoxication among East Asians than among Caucasians. The increased exposure to acetaldehyde in these people probably means that they are at increased risk of many types of cancer. (10)

Pregnancy. Women trying to get pregnant, or who are in the early stages of pregnancy, should not drink any alcohol at all. Alcohol inhibits growth and development of the foetus (fetus), particularly the brain and the nervous system. Alcohol especially damages the foetus during the first few days of pregnancy, well before the mother knows she is pregnant.

Other cautions

Some people are more prone to alcoholism, so if the disease runs in your family, or you've had a spot or two of binge drinking in the past, it may be best to avoid alcohol completely. If you don't already drink, any supposed benefits are probably not a good enough reason to start the habit. Also, these benefits seem to apply mainly to older people, after many years of moderate consumption with no binge drinking.

Excessive alcohol can destroy the liver, damage the brain, cause cancers (including breast cancer), heart and artery disease, and severely damage foetuses. The risk of cancer is higher if you drink alcohol, especially if you have insufficient folate in your diet. It also can have devastating social consequences.

Alcohol dehydrates the body and the brain cells. It is one of the few substances that manages to bypass some of the brain's dehydration protection mechanisms.

Excess alcohol or hard liquor like brandy, vodka or whiskey raises your insulin level. Long-term drinking can contribute to metabolic syndrome.

References

1. Cochrane AL, St Leger AS, Moore F. Factors associated with cardiac mortality in developed countries with particular reference to the consumption of wine. Lancet. 1979 May 12;1(8124):1017-20.

2. E.B Rimm, E.L Giovannucci, W.C Willett, G.A Colditz, A Ascherio, B Rosner, M.J Stampfer. Prospective study of alcohol consumption and risk of coronary disease in men. The Lancet, Volume 338, No. 8765, p464-468, 24 August 1991.

3. Kenneth J. Mukamal, Majken K. Jensen, Morten Gronbaek, Meir J. Stampfer, JoAnn E. Manson, Tobias Pischon, Eric B. Rimm. Drinking Frequency, Mediating Biomarkers, and Risk of Myocardial Infarction in Women and Men. Circulation, 29 August 2005; 112: 1406-1413. doi: 10.1161/CIRCULATIONAHA.105.537704.

4. Kaye Middleton Fillmorea, William C. Kerr, Tim Stockwell, Tanya Chikritzhs, Alan Bostrom. Moderate alcohol use and reduced mortality risk: Systematic error in prospective studies. Addiction Research & Theory, Volume 14, Issue 2, 2006.

5. World Health Organisation: Global status report on alcohol and health 2014. Retrieved online 3 September 2015.

6. Hans Olav Fekjaer. Alcohol - a universal preventive agent? A critical analysis. Addiction, December 2012. doi:10.1111/add.12104.

7. Craig S Knott, Ngaire Coombs, Emmanuel Stamatakis, Jane P Biddulph. All cause mortality and the case for age specific alcohol consumption guidelines: pooled analyses of up to 10 population based cohorts. 10 February 2015, BMJ 2015;350:h384.

8. Collins M.A., Neafsey E.J., Mukamal K.J., Gray M.O., Parks D.A., Das D.K., Korthuis R.J. Alcohol in moderation, cardioprotection, and neuroprotection: epidemiological considerations and mechanistic studies. Alcohol Clin Exp Res. 2009 Feb;33(2):206-19.

9. Juan I. Garaycoechea, Gerry P. Crossan, Frederic Langevin, Lee Mulderrig, Sandra Louzada, Fentang Yang, Guillaume Guilbaud, Naomi Park, Sophie Roerink, Serena Nik-Zainal, Michael R. Stratton & Ketan J. Patel. Alcohol and endogenous aldehydes damage chromosomes and mutate stem cells. Nature. Published online 03 January 2018. doi:10.1038/nature25154.

10. Seitz HK, Meier P. The role of acetaldehyde in upper digestive tract cancer in alcoholics. 2007. Transl Res. 149 (6): 293-7. doi:10.1016/j.trsl.2006.12.002. PMID 17543846.

11. Moss Margaret, Freed David. The cow and the coronary: Epidemiology, biochemistry and immunology. (2003). International journal of cardiology. 87. 203-16. 10.1016/S0167-5273(02)00201-2.