When I was a young child, my mother would sing a song to me: "My drink is water bright." In her youth she had joined the Temperance Society, which proclaimed that alcohol of all forms was bad and would shorten your life. Now, 100 years old come Christmas Day, she has whisky (one, or as many as she can get her hands on) every afternoon; also a liqueur in her morning coffee. Examining her diet, I sometimes say that she neglects none of the five food groups: sugar, fat, caffeine, salt and alcohol.

Is alcohol bad for you? Is alcohol good for you? Rather than simply saying yes to both questions, I want to set forth a few facts that are beyond debate.

First, let's note that "alcohol" itself is not a defined term. Chemists distinguish many forms of alcohol. The only one that you may be drinking (I hope) is ethyl alcohol, often called grain alcohol. This is the alcohol in beer and wine, and in distilled drinks such as whisky, brandy, rum and vodka. A lighter form is methyl alcohol, the same thing as methanol, or wood alcohol. You should definitely not be drinking this. It is a poison whose steady use causes blindness and death.

There are also many "higher alcohols," so named not because they are in any way better, but because they are heavier and denser than grain alcohol. Distilled liquors like whiskey and brandy contain small amounts of the higher alcohols. In this case they are known as fusel oils, or congeners, and they make the raw spirit taste terrible. The process of aging in wooden containers removes fusel oils and produces a palatable mature product.

Since my purpose is not to offer a guided tour of the wines of the world, I will say no more about specific drinks and simply note that when I say "alcohol" in what follows, I am referring exclusively to ethyl alcohol - called "grain alcohol," although it is easily produced by fermenting almost any form of fruit or vegetable.

Alcohol taken in large quantities is a poison. Heavy consumption, particularly over long periods of time, kills. If we are lucky, the only person it kills is the drinker. The organs most obviously affected are the liver, kidneys, and brain, and cirrhosis of the liver has long been known as the "drinker's disease."

It might seem logical to conclude that if imbibing large quantities of alcohol will kill you, then taking smaller quantities may do somewhat less harm but will still hurt you. Certainly, drinking alcohol should not be good for you. This was the prevailing view for many years, despite the fact that the conclusion drawn is not logical at all. Let's apply the same argument to food. Gross overeating will shorten your life, and in fact obesity has become one of America's main health worries. However, we do not argue from the dangers of obesity that one should not eat at all. Drinking too much is bad for you. But drinking a moderate amount?

The first hard evidence, as opposed to opinions based on moral argument, came like much else in life from France. The French government had for years sought to make people moderate their intake of wine. "Not more than a liter a day" was a widespread if unpopular slogan plastered all over the Paris Metro. At the same time, medical researchers in this country and elsewhere noticed a surprising and rather annoying statistic. French cuisine is traditionally high in oils, red meat, animal fats, butter and cream. According to American dieticians, Frenchmen should be keeling over in droves. In fact, France enjoys an unusually low rate of death from heart disease.

Could it be that food and wine go together, in more than the usual way?

The first evidence came from statistical studies showing that a moderate intake of red wine, maybe a glass a day, seemed to benefit the heart and blood vessels and lower cholesterol. This was at once disputed, not because anyone could fault the statistics but because the results conflicted with many people's preconceived ideas of what is morally right - "Look not on the wine when it is red."

But as the studies went on, the evidence strengthened even though the physical explanations were suspect. Alcohol serves as a blood-thinner, and inhibits the formation of clots. Maybe. Or, since the chemical compounds known as sterols are forms of alcohol, and since cholesterol is a sterol, alcohol in the blood might dissolve cholesterol, or prevent it from forming, or boost the proportion of "good" cholesterol. True? Could be.

However, regardless of the validity of the explanations, the beneficial effects of a moderate amount of alcohol as a part of diet, particularly in older people, grow stronger and stronger. The definition of "moderate" has also changed. In a recent Dutch study of people over 55, the benefits were most pronounced in those who had one to three drinks a day. A similar French study showed maximum benefits at three to four drinks a day. (The difference, according to one French research worker, merely reflects the fact that the Dutch are less likely to admit how much they drink.)

It's not just red wine, although that does seem to provide the most positive effects. Beer and hard liquor, contrary to long- held opinion, also have protective qualities.

And it's not just for the heart. Alcohol, in moderate quantities, protects against strokes, the irreversible eye disease known as macular degeneration, and, most recent and perhaps most surprising, Alzheimer's disease. Surprising, because it has long been held that alcohol in the blood stream kills brain cells, so you would expect it to hasten the onset of Alzheimer's disease and other cognitive failings.

I have seen no explanation for this last result, but the finding itself is based on a careful and scrupulously conducted ten-year longitudinal study of more than 5,000 people. A friend of mine explains based on his curious version of the theory of evolution: "It's the survival of the fittest. Hit them with alcohol, and only your strongest brain cells will survive."

Although we have no solid reasons as to why, and although some will certainly deny the results on moral grounds, the medical evidence is increasingly hard to dismiss. "Eat, drink, and be merry; for tomorrow we die." But maybe with the help of a moderate amount of alcohol, we will survive until the day after tomorrow.

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