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Beer is the world's oldest and most popular alcoholic beverage. It is produced by the fermentation of sugars derived from starch-based material — the most common being malted barley; however, wheat, corn, and rice are also widely used, usually in conjunction with barley. Less widely used starch sources include millet, sorghum and cassava root in Africa, potato in Brazil, and agave in Mexico, among others.
The starch source is steeped in water, along with certain enzymes, to produce a sugary wort which is then flavoured with herbs, fruit or most commonly hops. Yeast is then used to cause fermentation, which produces alcohol and other waste products from anaerobic respiration of the sugars. The process of beer production is called brewing.
Beer uses many varying ingredients, production methods and traditions. The type of yeast and production method may be used to classify beer into ale, lager and spontaneously fermented beers. Some beer writers and organizations differentiate and categorize beers by various factors into beer styles. Alcoholic beverages fermented from non-starch sources such as grape juice (wine) or honey (mead), as well as distilled beverages, are not classified as beer.
- Main article: Alcohol consumption and health
Brewer's yeast is known to be a rich source of nutrients; therefore, as expected, beer can contain significant amounts of nutrients, including magnesium, selenium, potassium, phosphorus, biotin, and B vitamins. In fact, beer is sometimes referred to as "liquid bread". Some sources maintain that filtered beer loses much of its nutrition.
There is conclusive evidence that heavy and prolonged consumption of alcohol leads to liver disease including cirrhosis and malignancy. Heavy alcohol consumption has also been linked to pancreatitis and gout.
Beer ranges from less than 3% alcohol by volume (abv) to almost 30% abv. The alcohol content of beer varies by local practice or beer style. The pale lagers that most consumers are familiar with fall in the range of 4–6%, with a typical abv of 5%. The customary strength of British ales is quite low, with many session beers being around 4% abv. Some beers, such as tafelbier (table beer) are of such low alcohol content (1%~4%) that they are served instead of soft drinks in some schools. In the United states beer with an alcohol content over a certain level (? 5%) can not be called beer for marketing purposes. The term 'malt liquor' is often used instead. Many imported 'beers', such as Singha Beer from Thailand, can not be labeled as beer in America due to its high percentage of alcohol by volume.
The alcohol in beer comes primarily from the metabolism of sugars that are produced during fermentation. The quantity of fermentable sugars in the wort and the variety of yeast used to ferment the wort are the primary factors that determine the amount of alcohol in the final beer. Additional fermentable sugars are sometimes added to increase alcohol content, and enzymes are often added to the wort for certain styles of beer (primarily "light" beers) to convert more complex carbohydrates (starches) to fermentable sugars. Alcohol is a waste product of yeast metabolism and is toxic to the yeast; typical brewing yeast cannot survive at alcohol concentrations above 12% by volume. Low temperatures and too little fermentation time decreases the effectiveness of yeasts, and consequently decreases the alcohol content.
- List of countries ordered by per capita beer consumption
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- Genetic variation in alcohol dehydrogenase and the beneficial effect of moderate alcohol consumption on myocardial infarction.
- Light-to-moderate alcohol consumption and risk of stroke among U.S. male physicians.
- Roles of drinking pattern and type of alcohol consumed in coronary heart disease in men.
- Bamforth, C. W. (September 17–20, 2006). "Beer as liquid bread: Overlapping science.". World Grains Summit 2006: Foods and Beverages. Retrieved on 2006-11-06.
- Arthur Harden and Sylvester Solomon Zilva (July 21, 1924). "CXLVII. Investigation of barley, malt, and beer for vitamins B and C" (pdf). Biochemical department, Lister Institute. Retrieved on 2006-11-06.
- Why our beer is special and, dare we say, better; No filtering. Franconia Notch Brewing Company. URL accessed on 2006-11-06.
-  Gout associated with Beer Drinking
- The Guardian. School dinner? Mine's a lager, please