Tuesday, March 30, 2010

Alcohol (ethanol, grain alcohol, ethyl alcohol)


A common term for the simple alcohol ETHANOL, the product of FERMENTATION. As a constituent of alcoholic beverages, ethanol is the most common, and longest used, sedative. To produce alcohol, special strains of yeast are incubated with CARBOHYDRATES of FRUIT juices and GRAINS together with other nutrients.
Under ANAEROBIC conditions (in the absence of oxygen), these microorganisms ferment sugar to ethanol and CARBON DIOXIDE to obtain energy. The immediate product of the fermentation of grapes is WINE. When malted grains and hops are fermented, the product is BEER. Distillation, a process introduced in the Middle Ages, produces alcoholic beverages with a higher alcohol content. These include rum, whiskey, liqueurs, and the like. Beer and wine are perhaps the most popular beverages among moderate drinkers. A mug of beer (11 oz., 4.5 percent), a glass of table wine (4 oz.) and a shot (jigger;
1.5 fl.oz.) of liquor (80 proof) contain about the same amount of alcohol (9 to 13 grams.) Excessive consumption of alcoholic beverages can cause MALNUTRITION because alcoholic beverages contain little else besides CALORIES. A glass of red wine contains 88 calories; a bottle of regular beer, 146; and a shot (1.5 fl. oz.) of whiskey (90 proof), 110 calories. VITAMIN, PROTEIN, and MINERAL content of alcohol is exceedingly low, though wine may contain a significant amount of IRON. For this reason, alcoholic beverages are classified as low-nutrient density or EMPTY CALORIES. To the extent they are consumed, they displace nutrient-dense foods. The blood alcohol level is affected by the amount of alcohol ingested. Water and juice slow the absorption of alcohol, while carbonation increases the rate of uptake into the bloodstream. Alcohol taken with food is less intoxicating. How alcohol is metabolized is another factor. A portion of the ingested alcohol is destroyed by ENZYMES in the stomach that are more active in men than in women; consequently, women generally have a lower tolerance to alcohol. The liver’s capacity to destroy alcohol in the blood is limited, and when the liver’s metabolic system is saturated, a fraction of ethanol in the blood is destroyed each hour. The remaining alcohol readily penetrates the bloodbrain barrier and interacts with the central nervous system. Alcohol can pass from maternal blood into breast milk; therefore, lactating mothers may wish to abstain from drinking.
Some studies suggest that a single alcoholic drink a day may slightly reduce the risk of heart attack and stroke in some individuals. Moderate alcohol consumption increases the level of HDL, the beneficial form of cholesterol that tends to protect against heart disease. Alcohol also inhibits platelet formation, which is required to form blood clots. Moderate alcohol use may also help prevent age-related decline in reasoning and problem solving. The apparent benefits decline after more than one or two drinks, however. The American Heart Association does not recommend drinking alcoholic beverages to prevent heart disease because of the hazards of alcohol abuse.