Nearly all research into the positive medical benefits of wine consumption makes a distinction between moderate consumption and heavy or binge drinking. Moderate levels of consumption vary by the individual according to age, gender, genetics, weight and body stature, as well as situational conditions, such as food consumption or use of drugs. In general, woman absorb alcohol more quickly than men due to their lower body water content, so their moderate levels of consumption may be lower than those for a male of equal age. Some experts define "moderate consumption" as less than one 5-US-fluid-ounce (150 ml) glass of wine per day for women and two glasses per day for men.
The view of consuming wine in moderation has a history recorded as early as the Greek poet Eubulus (360 BC) who believed that three bowls (kylix) were the ideal amount of wine to consume. The number of three bowls for moderation is a common theme throughout Greek writing; today the standard 750 ml wine bottle contains roughly the volume of three kylix cups (250 ml or 8 fl oz each). However, the kylix cups would have contained a diluted wine, at a 1:2 or 1:3 dilution with water. In his circa 375 BC play Semele or Dionysus, Eubulus has Dionysus say:
Heavy alcohol consumption has been shown to have a damaging effect on the cellular processes that create bone tissue, and long-term alcoholic consumption at high levels increases the frequency of fractures. Epidemiological studies (studies done by interviewing subjects and studying their health records) have found a positive association between moderate alcohol consumption and increased bone mineral density (BMD). Most of this research has been conducted with postmenopausal women, but one study in men concluded that moderate consumption of alcohol may also be beneficial to BMD in men.
The International Agency for Research on Cancer of the World Health Organization has classified alcohol as a Group 1 carcinogen.
Studies have shown that heavy drinkers put themselves at greater risk for heart disease and developing potentially fatal cardiac arrhythmias. Excessive alcohol consumption can cause higher blood pressure, increase cholesterol levels and weakened heart muscles. Studies have shown that moderate wine drinking can improve the balance of low-density lipoprotein (LDL or "bad" cholesterol) to high-density lipoprotein (HDL "good" cholesterol), which has been theorized as to clean up or remove LDL from blocking arteries. The main cause of heart attacks and the pain of angina is the lack of oxygen caused by blood clots and atheromatous plaque build up in the arteries. The alcohol in wine has anticoagulant properties that limits blood clotting by making the platelets in the blood less prone to stick together and reducing the levels of fibrin protein that binds them together.
Professional cardiology associations recommend that people who are currently nondrinkers should not start drinking alcohol.
One of the short-term effects of alcohol is impaired mental function, which can cause behavioral changes and memory impairment. Long-term effects of heavy drinking can inhibit new brain cell development and increase the risk for developing major depressive disorders. Studies have linked moderate alcohol consumption to lower risk of developing Alzheimer's and dementia though wine's role in this link is not yet fully understood. A 2009 study by Wake Forest University School of Medicine suggest that moderate alcohol consumption may help healthy adults ward off the risks of developing dementia but can accelerate declining memory for those already suffering from cognitive impairment. The reason for the potential positive benefit of moderate consumption is not yet identified and may even be unrelated to the alcohol but rather other shared lifestyle factors of moderate drinkers (such as exercise or diets). If it is the moderate consumption, researchers theorize that it may be alcohol's role in promoting the production of "good cholesterol" which prevents blood platelets from sticking together. Another potential role of alcohol in the body may be in stimulating the release of the chemical acetylcholine which influences brain function and memory.
Research has shown that moderate levels of alcohol consumed with meals does not have a substantial impact on blood sugar levels. A 2005 study presented to the American Diabetes Association suggest that moderate consumption may lower the risk of developing Type 2 diabetes.
The anti-bacterial nature of alcohol has long been associated with soothing stomach irritations and ailments like traveler's diarrhea where it was a preferred treatment to the less palatable bismuth treatments. The risk of infection from the bacterium Helicobacter pylori, strongly associated with causing gastritis and peptic ulcers as well as being closely linked to stomach cancer, appears to lessen with moderate alcohol consumption. A German study conducted in the late 1990s showed that non-drinkers had slightly higher infection rates of Helicobacter pylori than moderate wine and beer drinkers.
Wine's positive effects on the metabolism of cholesterol has been suggested as a link to lower occurrences of gallstones among moderate drinkers since cholesterol is a major component of gallstones.
There are several potential causes of so-called "red wine headaches", including histamines/tyramines and the breakdown of some phenolic compounds in wine that carry the chemical messenger for serotonin. One culprit that is regularly dismissed by allergists as an unlikely cause of red wine headaches is sulfites which are used as a preservative in wine. Wine, like other alcoholic beverages, is a diuretic which promotes dehydration that can lead to headaches (such as the case often experienced with hangovers). In 2006, researchers from the University of California, Davis announced finding from genetic mapping that amino acids in wine that have been slightly modified by the fermentation process may be the cause of wine related headaches. The research suggest changes in fermentation techniques may help alleviate the risk for wine drinkers sensitive to these amino acids.
Compared to many beers and non-diet sodas, a serving of wine has a moderate amount of calories. A standard 5 fl oz (150 ml) serving of red wine (based on an average alcohol content of 13%) contains approximately 106 calories and 2.51 g of carbohydrates. A similar serving of white wine contains approximately 100 calories and 1.18 g of carbohydrates.
Psychological and social
Danish epidemiological studies suggest that a number of psychological health benefits are associated with drinking wine. In a study testing this idea, Mortensen et al. (2001) measured socioeconomic status, education, IQ, personality, psychiatric symptoms, and health related behaviors, which included alcohol consumption. The analysis was then broken down into groups of those who drank beer, those who drank wine, and then those who did and did not drink at all. The results showed that for both men and women drinking wine was related to higher parental social status, parental education and the social status of the subjects. When the subjects were given an IQ test, wine drinkers consistently scored higher IQs than their counterpart beer drinkers. The average difference of IQ between wine and beer drinkers was 18 points. In regards to psychological functioning, personality, and other health-related behaviors, the study found wine drinkers to operate at optimal levels while beer drinkers performed below optimal levels. As these social and psychological factors also correlate with health outcomes, they represent a plausible explanation for at least some of the apparent health benefits of wine.
In 2008, researchers from Kingston University in London discovered red wine to contain high levels of toxic metals relative to other beverages in the sample. Although the metal ions, which included chromium, copper, iron, manganese, nickel, vanadium and zinc, were also present in other plant-based beverages, the sample wine tested significantly higher for all metal ions, especially vanadium. Risk assessment was calculated using "target hazard quotients" (THQ), a method of quantifying health concerns associated with lifetime exposure to chemical pollutants. Developed by the Environmental Protection Agency in the US and used mainly to examine seafood, a THQ of less than 1 represents no concern while, for example, mercury levels in fish calculated to have THQs of between 1 and 5 would represent cause for concern.
The researchers stressed that a single glass of wine would not lead to metal poisoning, pointing out that their THQ calculations were based on the average person drinking one-third of a bottle of wine (250 ml) every day between the ages of 18 and 80. However the "combined THQ values" for metal ions in the red wine they analyzed were reported to be as high as 125. A subsequent study by the same university using a meta analysis of data based on wine samples from a selection of mostly European countries found equally high levels of vanadium in many red wines, showing combined THQ values in the range of 50 to 200, with some as high as 350.
The findings sparked immediate controversy due to several issues: the study's reliance on secondary data; the assumption that all wines contributing to that data were representative of the countries stated; and the grouping together of poorly understood high-concentration ions, such as vanadium, with relatively low-level, common ions such as copper and manganese. While some publications printed lists of countries showing the "worst offenders" and reported that wine from other countries did not pose a health risk, others pointed out that the lack of identifiable wines and grape varieties, specific producers or even wine regions, provided only misleading generalizations that should not be relied upon in choosing wines.
In a news bulletin following the widespread reporting of the findings, the UK's National Health Service (NHS) were also concerned that "the way the researchers added together hazards from different metals to produce a final score for individual wines may not be particularly meaningful". Commentators in the US questioned the relevance of seafood-based THQ assessments to agricultural produce, with the TTB, responsible for testing imports for metal ion contamination, have not detected an increased risk. George Solas, quality assessor for the Canadian Liquor Control Board of Ontario (LCBO) claimed that the levels of heavy metal contamination reported were within the permitted levels for drinking water in tested reservoirs.
Whereas the NHS also described calls for improved wine labeling as an "extreme response" to research which provided "few solid answers", they acknowledged the authors call for further research to investigate wine production, including the influence that grape variety, soil type, geographical region, insecticides, containment vessels and seasonal variations may have on metal ion uptake.
Although red wine contains many chemicals under basic research for their potential health benefits, resveratrol has been particularly well studied and evaluated by regulatory authorities, such as the European Food Safety Authority and US Food and Drug Administration which identified it and other such phenolic compounds as not sufficiently understood to confirm their role as physiological antioxidants.
Cinnamates have been shown to have more antioxidant activity when exposed in vitro to the Fenton reaction (catalytic Fe(II) with hydrogen peroxide) than the other natural phenols present in wine.
Research on potential health effects of resveratrol is in its infancy and the long-term effects of supplementation in humans are not known.
Resveratrol is a stilbenoid phenolic compound found in wine produced in the grape skins and leaves of grape vines. It has received considerable attention in both the media and medical research community for its potential health benefits which remain unproven in humans.
The production and concentration of resveratrol is not equal among all the varieties of wine grapes. Differences in clones, rootstock, Vitis species as well as climate conditions can affect the production of resveratrol. Also, because resveratrol is part of the defence mechanism in grapevines against attack by fungi or grape disease, the degree of exposure to fungal infection and grape diseases also appear to play a role. The Muscadinia family of vines, which has adapted over time through exposure to North American grape diseases such as phylloxera, has some of the highest concentrations of resveratrol among wine grapes. Among the European Vitis vinifera, grapes derived from the Burgundian Pinot family tend to have substantially higher amounts of resveratrol than grapes derived from the Cabernet family of Bordeaux. Wine regions with cooler, wetter climates that are more prone to grape disease and fungal attacks such as Oregon and New York tend to produce grapes with higher concentrations of resveratrol than warmer, dry climates like California and Australia.
Although red wine and white vine varieties produce similar amounts of resveratrol, red wine contains more than white, since red wines are produced by maceration (soaking the grape skins in the mash). Other winemaking techniques, such as the use of certain strains of yeast during fermentation or lactic acid bacteria during malolactic fermentation, can have an influence on the amount of resveratrol left in the resulting wines. Similarly the use of certain fining agents during the clarification and stabilization of wine can strip the wine of some resveratrol molecules.
The prominence of resveratrol in the news and its association with positive health benefits has encouraged some wineries to highlight it in their marketing. In the early 21st century, the Oregon producer Willamette Valley Vineyards sought approval from the Alcohol and Tobacco Tax and Trade Bureau (TTB) to state on their wine labels the resveratrol levels of their wines which ranged from 19 to 71 micromoles per liter (higher than the average 10 micromoles per liter in most red wines). The TTB gave preliminary approval to the winery, making it the first to use such information on its labels. While resveratrol is the most widely publicized, there are other phenolic components in wine that have been the focus of medical research for potential health benefits, including the compounds catechin and quercetin, none of which has been proven to have any health value in humans.
Red grapes are high in anthocyanins which are the source of the color of various fruits, such as red grapes. The darker the red wine, the more anthocyanins present.
Following dietary ingestion, anthocyanins undergo rapid and extensive metabolism that makes the biological effects presumed from in vitro studies unlikely to apply in vivo.
Although anthocyanins are under basic and early-stage clinical research for a variety of disease conditions, there exists no sufficient evidence that they have any beneficial effect in the human body. The US FDA has issued warning letters, e.g., to emphasize that anthocyanins are not a defined nutrient, cannot be assigned a dietary content level and are not regulated as a drug to treat any human disease.
Early medicine was intimately tied with religion and the supernatural, with early practitioners often being priests and magicians. Wine's close association with ritual made it a logical tool for these early medical practices. Tablets from Sumeria and papyri from Egypt dating to 2200 BC include recipes for wine based medicines, making wine the oldest documented man made medicine.
When the Greeks introduced a more systematized approach to medicine, wine retained its prominent role. The Greek physician Hippocrates considered wine a part of a healthy diet, and advocated its use as a disinfectant for wounds, as well as a medium in which to mix other drugs for consumption by the patient. He also prescribed wine as a cure for various ailments ranging from diarrhea and lethargy to pain during childbirth.
The medical practices of the Romans involved the use of wine in a similar manner. In his 1st-century work De Medicina, the Roman encyclopedist Aulus Cornelius Celsus detailed a long list of Greek and Roman wines used for medicinal purposes. While treating gladiators in Asia Minor, the Roman physician Galen would use wine as a disinfectant for all types of wounds, and even soaked exposed bowels before returning them to the body. During his four years with the gladiators, only five deaths occurred, compared to sixty deaths under the watch of the physician before him.
Religion still played a significant role in promoting wine's use for health. The Jewish Talmud noted wine to be "the foremost of all medicines: wherever wine is lacking, medicines become necessary." In his first epistle to Timothy, Paul the Apostle recommended that his young colleague drink a little wine every now and then for the benefit of his stomach and digestion. While the Islamic Koran contained restrictions on all alcohol, Islamic doctors such as the Persian Avicenna in the 11th century AD noted that wine was an efficient digestive aid but, because of the laws, were limited to use as a disinfectant while dressing wounds. Catholic monasteries during the Middle Ages also regularly used wine for medical treatments. So closely tied was the role of wine and medicine, that the first printed book on wine was written in the 14th century by a physician, Arnaldus de Villa Nova, with lengthy essays on wine's suitability for treatment of a variety of medical ailments such dementia and sinus problems.
The lack of safe drinking water may have been one reason for wine's popularity in medicine. Wine was still being used to sterilize water as late as the Hamburg cholera epidemic of 1892 in order to control the spread of the disease. However, the late 19th century and early 20th century ushered in a period of changing views on the role of alcohol and, by extension, wine in health and society. The Temperance movement began to gain steam by touting the ills of alcoholism, which was eventually defined by the medical establishment as a disease. Studies of the long- and short-term effects of alcohol caused many in the medical community to reconsider the role of wine in medicine and diet. Soon, public opinion turned against consumption of alcohol in any form, leading to Prohibition in the United States and other countries. In some areas, wine was able to maintain a limited role, such as an exemption from Prohibition in the United States for "therapeutic wines" that were sold legally in drug stores. These wines were marketed for their supposed medicinal benefits, but some wineries used this measure as a loophole to sell large quantities of wine for recreational consumption. In response, the United States government issued a mandate requiring producers to include an emetic additive that would induce vomiting above the consumption of a certain dosage level.
Throughout the mid to early 20th century, health advocates pointed to the risk of alcohol consumption and the role it played in a variety of ailments such as blood disorders, high blood pressure, cancer, infertility, liver damage, muscle atrophy, psoriasis, skin infections, strokes, and long-term brain damage. Studies showed a connection between alcohol consumption among pregnant mothers and an increased risk of mental retardation and physical abnormalities in what became known as fetal alcohol syndrome, prompting the use of warning labels on alcohol-containing products in several countries.
The 1990s and early 21st century saw a renewed interest in the health benefits of wine, ushered in by increasing research suggesting that moderate wine drinkers have lower mortality rates than heavy drinkers or teetotalers. In November 1991, the U.S. news program 60 Minutes aired a broadcast on the so-called "French Paradox". Featuring the research work of Bordeaux scientist Serge Renaud, the broadcast dealt with the seemingly paradoxical relationship between the high fat/high dairy diets of French people and the low occurrence of cardiovascular disease among them. The broadcast drew parallels to the American and British diets which also contained high levels of fat and dairy but which featured high incidences of heart disease. One of the theories proposed by Renaud in the broadcast was that moderate consumption of red wine was a risk-reducing factor for the French and that wine could have more positive health benefits yet to be studied. Following the 60 Minutes broadcast, sales of red wine in the United States jumped 44% over previous years.
This changing view of wine can be seen in the evolution of the language used in the U.S. Food and Drug Administration Dietary Guidelines. The 1990 edition of the guidelines contained the blanket statement that "wine has no net health benefit". By 1995, the wording had been changed to allow moderate consumption with meals providing the individual had no other alcohol-related health risk. From a research perspective, scientists began differentiating alcohol consumption among the various classes of beverages – wine, beer, and spirits. This distinction allowed studies to highlight the positive medical benefits of wine apart from the mere presence of alcohol. However wine drinkers tend to share similar lifestyle habits – better diets, regular exercise, non-smoking – that may in themselves be a factor in the supposed positive health benefits compared to drinkers of beer and spirits or those who abstain completely.