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Wine is an alcoholic beverage made of fermented grape juice. The natural chemical balance of grapes is such that they can ferment without the addition of sugars, acids, enzymes or other nutrients. Wine is produced by fermenting crushed grapes using various types of yeast which consume the sugars found in the grapes and convert them into alcohol. Different varieties of grapes and strains of yeasts are used depending on the types of wine being produced.
|Red table wine</tr>
Nutritional value per 100 g (3.5 oz)
|Energy 80 kcal 360 kJ|
|10.6 g alcohol is 13%vol.
100 g wine is approximately 100 ml (3.4 fl oz.)
Sugar and alcohol content can vary.
Source: USDA Nutrient database</td></tr></table>
Although excessive alcohol consumption has adverse health effects, epidemiological studies have consistently demonstrated that moderate consumption of alcohol and wine is statistically associated with a decrease in death due to cardiovascular events such as heart failure. In the United States, a boom in red wine consumption was initiated in the 1990s by the TV show 60 Minutes, and additional news reports on the French paradox. The French paradox refers to the comparatively lower incidence of coronary heart disease in France despite high levels of saturated fat in the traditional French diet. Some epidemiologists suspect that this difference is due to the higher consumption of wines by the French, but the scientific evidence for this theory is limited. The average moderate wine drinker is more likely to exercise more, to be more health conscious, and to be of a higher educational and socioeconomic class, evidence that the association between moderate wine drinking and health may be related to confounding factors.
Population studies have observed a J curve association between wine consumption and the risk of heart disease. This means that heavy drinkers have an elevated risk, while moderate drinkers (at most two five-ounce servings of wine per day) have a lower risk than non-drinkers. Studies have also found that moderate consumption of other alcoholic beverages may be cardioprotective, although the association is considerably stronger for wine. Also, some studies have found increased health benefits for red wine over white wine, though other studies have found no difference. Red wine contains more polyphenols than white wine, and these are thought to be particularly protective against cardiovascular disease.
A chemical in red wine called resveratrol has been shown to have both cardioprotective and chemoprotective effects in animal studies. Low doses of resveratrol in the diet of middle-aged mice has a widespread influence on the genetic levers of aging and may confer special protection on the heart. Specifically, low doses of resveratrol mimic the effects of what is known as caloric restriction - diets with 20-30 percent fewer calories than a typical diet. Resveratrol is produced naturally by grape skins in response to fungal infection, including exposure to yeast during fermentation. As white wine has minimal contact with grape skins during this process, it generally contains lower levels of the chemical. Other beneficial compounds in wine include other polyphenols, antioxidants, and flavonoids.
Red wines from the south of France and from Sardinia in Italy have been found to have the highest levels of procyanidins, which are compounds in grape seeds suspected to be responsible for red wine's heart benefits. Red wines from these areas have between two and four times as much procyanidins as other red wines. Procyanidins suppress the synthesis of a peptide called endothelin-1 that constricts blood vessels.
A 2007 study found that both red and white wines are effective anti-bacterial agents against strains of Streptococcus. Also, a report in the October 2008 issue of Cancer Epidemiology, Biomarkers and Prevention, posits that moderate consumption of red wine may decrease the risk of lung cancer in men.
While evidence from laboratory and epidemiological (observational) studies suggest a cardioprotective effect, no controlled studies have been completed on the effect of alcoholic drinks on the risk of developing heart disease or stroke. Excessive consumption of alcohol can cause cirrhosis of the liver and alcoholism; the American Heart Association cautions people to "consult your doctor on the benefits and risks of consuming alcohol in moderation."
Wine's effect on the brain is also under study. One study concluded that wine made from the Cabernet Sauvignon grape reduces the risk of Alzheimer's Disease. Another study concluded that among alcoholics, wine damages the hippocampus to a greater degree than other alcoholic beverages.
Sulphites are present in all wines and are formed as a natural product of the fermentation process, and many wine producers add sulfur dioxide in order to help preserve wine. Sulfur dioxide is also added to foods such as dried apricots and orange juice. The level of added sulfites varies, and some wines have been marketed with low sulfite content. Sulphites in wine can cause some people, particularly those with asthma, to have adverse reactions.
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