beer and tea(Tony Cenicola/The New York Times)

Andrew Kligerman is a native New Yorker who now lives in Research Triangle Park, N.C., where he’s a genetic toxicologist and research biologist. He’s also an avid vegetable gardener, homebrewer, sourdough bread maker, and cook, especially of Asian cuisine. And one day, he got to wondering about beer and tea. Here is his fascinating rumination. –MB

Have you ever wondered why beer was the prevalent drink in Europe and tea the drink of choice in Asian countries? I got to thinking about this partly because I have brewed beer at home for more than 20 years.

Beer is believed to have originated in the Middle East. Barley was a staple of the area and used in cakes and breads. It was eventually discovered that if barley was allowed to germinate and then was dried, the grain would develop a noticeable sweetness that we now know is due the action of amylases present in the grain. These enzymes convert the long-chain starches to various sweet mono- and disaccharide sugars.

When the grain was mixed with water and wild yeast acted upon the sugars, a bubbly concoction evolved that many found quite pleasant. If fact, it has been hypothesized that one of the factors that led to grain domestication was the “high” people obtained from beer [Katz, S.H. and Voigt,M.M. Bread and Beer: The Early Use of Cereals in the Human Diet, Expeditions 28 (2), 23-34 (1986)]. In addition, this mildly alcoholic beverage had ample nutrition, and the level of alcohol actually helped to preserve the beverage. In Western Europe there is evidence that the Picts were producing a fermented beverage around 6500 B.C. and were brewing a barley-based beer before the Roman invasion (Noonan,G.J. Scotch Ale, Classic Beer Style Series 8, Brewers Publications,Bolder, CO 1993). Apparently, King Niall of the Nine Hostages orchestrated a genocidal campaign against the Picts to learn the secret of heather ale.

As population density and travel increased, fermented beverages such as beer became a way to transport a nutritional food stuff as well as a source of safe liquid refreshment. There was an old adage “…the water can kill you but the beer won’t.” People in the West did not realize that boiling water could purify it.

But what about people in Asia?

According to this site, www.stashtea.com/facts.htm, the story of tea began in ancient China over 5,000 years ago. Legend has it that Shen Nung, an early emperor, was a skilled ruler, creative scientist, and patron of the arts. His far-sighted edicts required, among other things, that all drinking water be boiled as a hygienic precaution. One summer day while visiting a distant region of his realm, he and the court stopped to rest. In accordance with his ruling, the servants began to boil water for the court to drink. Dried leaves from the near by bush fell into the boiling water, and a brown liquid resulted. As a scientist, the Emperor was interested in the new liquid, drank some, and found it very refreshing. And so, tea was created. (This myth maintains such a practical narrative, that many mythologists believe it may relate closely to the actual events, now lost.)

Thus, two vastly different cultures separated by thousands of miles developed distinctly different ways to deal with polluted water for consumption. One other fact about alcohol. Alcohol has toxicological effects and can directly lead to cellular damage. The body must rid itself of this toxin, and the alcohol is metabolized to acetaldehyde through the action of alcohol dehydrogenase. It has been found that approximately half of the Pacific Rim Asian population (Chinese, Japanese, Koreans) possess an atypical alcohol dehydrogenase (ADH) known as ADH2*2 that leads to unusually rapid conversion of ethanol to acetaldehyde (http://en.wikipedia.org/wiki/Alcohol_flush_reaction).

Since acetaldehyde is more toxic than alcohol, its increased accumulation causes flushing in the human body. Moreover, the normal aldehyde dehydrogenase (ALDH2), synthesized in the liver, oxidizes acetaldehyde into acetic acid. A mutant ALDH2 enzyme (known as ALDH2*2) is also found in about 50% of Japanese, Chinese, Korean, Taiwanese, and Vietnamese population. This enzyme however, is only about 8% as effective as the normal, wild-type enzyme (ALDH*1)in detoxifying acetaldehyde [Xiao,Q., Weiner, H., Crabb, D.W. J. Clin. Invest. 98(9): 2027-2032 (1996)]. Thus, in many Asians, not only is alcohol more rapidly broken down into acetaldehyde, but this toxin remains in the body longer due to its slower metabolism to innocuous acetic acid. Thus, a large number of the people of Asian descent are very sensitive to alcohol. After consuming one or two alcoholic beverages, they may experience symptoms which include dizziness, nausea, headaches, an increased pulse, occasional extreme drowsiness, and occasional skin swelling and itchiness. These unpleasant side effects often prevent further drinking that would lead to further intoxication.

Could it be that a culture rich in an alcohol tradition evolved in the West to deal with the problem of poor potable water quality; while in the East, to deal with the same problem, a culture evolved centered around tea because of the presence of a mutation in a gene? Food (or drink) for thought!