Yeasts, rather dull life forms in most respects, have one endearing trait: provided with sugar, they produce carbon dioxide…and an interesting chemical called “alcohol.”
Nobody knows who first discovered that yeast could turn ordinary grape juice or grain brew into something quite different, but by 1500 B.C., beer and wine-making were well-established in the Middle East. Today, people drink three main kinds of alcoholic beverages: beers, made from grain through brewing and fermentation, which are three to eight percent alcohol; wines, fermented from fruits such as grapes, which are eight to 12 percent alcohol; and distilled beverages, such as whiskey, gin and vodka, which are 40 to 50 percent alcohol.
Alcohol is easily absorbed into the bloodstream through the walls of the small intestine. How quickly it is absorbed determines how quickly its effects are felt. (Drinking while eating is less intoxicating than drinking on an empty stomach, because the fat and protein in the foods in the stomach delay alcohol absorption.)
Alcohol is called a “depressant,” not because it depresses people emotionally, but because it depresses the nervous system’s level of activity. Since this includes depressing inhibitions, people who are moderately intoxicated tend to act more exhilarated than depressed.
The body immediately goes to work metabolizing alcohol. A small amount is processed by the kidneys and excreted in the urine, and a small amount is processed through the lungs and exhaled in the breath (which is why a breath test can determined blood alcohol concentration), but the bulk of it is metabolized by the liver, at a rate of about three fourths of an ounce to one ounce of whisky an hour (or about half a glass of wine or beer an hour). Most people drink more rapidly than that, so their blood alcohol concentration rises.
At .08 percent, in Saskatchewan, you’re legally intoxicated and cannot drive a motor vehicle. At 0.2 percent (obtained by drinking about 10 ounces of whiskey), a drinker has trouble controlling his emotions and may burst into laughter or tears. He also has trouble controlling his legs and will want to lie down.
At 0.3 percent (attainable by rapidly drinking a pint of whiskey), the drinker will have trouble understanding what’s being said and may pass out. From 0.35 to 0.5 percent, the part of the brain that controls breathing and heart action may be affected, and above 0.5 percent can be fatal.
It may not be fair, but if a man and a woman drink the same amount, the woman will become more intoxicated. An enzyme in the stomach breaks down some of the alcohol before it reaches the bloodstream, and that enzyme is four times more active in men than it is in women. Also, women tend to have less body water and more fat than men, proportionately. Alcohol is more soluble in water than in fat, so it becomes more highly concentrated in a woman’s body than in a man’s. And finally, men tend to be larger than women.
The moderate long-term use of alcohol is generally not considered a health risk, but heavy drinking definitely is. Heavy drinking promotes cancers of the mouth, throat and esophagus; ulcers; gastritis; strokes; cirrhosis of the liver and inflammation of the pancreas. Nervous system disorders, including blackouts, hallucination and extreme tremor (as in delirium tremens, or “the DTs”). Permanent damage to the brain and central nervous system is possible. And pregnant women who drink heavily may give birth to children with birth abnormalities, both physical and mental.
On the positive side, moderate consumption of alcohol may actually be beneficial. A recent study in the British Medical Journal indicates that those who drink moderately may live longer than those who don’t drink at all. Alcohol appears to reduce the risk of heart disease to such an extent that the American Medical Association, in a study published in September, estimated that if the entire U.S. population quit drinking alcohol, there would be an additional 81,000 deaths from heart disease every year.
The reason is unclear. One theory is that alcohol boosts the production of high-density lipoprotein cholesterol, which helps flush the coronary arteries of fatty deposits of low-density lipoprotein cholesterol. Another theory is that alcohol prevents blood clots, which can trigger heart attacks. And some psychologists feel that the pleasure of a drink or two in the company of friends may play an important role in reducing stress.
Health risks or benefits aside, “the pleasure of a drink or two in the company of friends,” more than anything else, is probably what’s kept people imbibing this by-product of yeast for 4,000 years.
