Through a Chemist's Eyes

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THROUGH A CHEMIST'S EYES:

A DISPASSIONATE LOOK AT ALCOHOL

by John Emsley, Ph.D.

CONSUMERS' RESEARCH July 1995, pp. 19-24

We all have alcohol in our body in small amounts, and it has no effect because there is so little of it. When we suddenly increase the amount, by drinking a lot of it, then we experience some rather unusual effects--elation, to begin with, but deflation a few hours later. Were alcohol to be discovered today its sale to the public would never be permitted because of its potentially lethal side-effects.

There are people in the world, such as Muslims and Mormons, for whom alcohol is taboo. There are those who suspect alcoholic drinks of harboring unwanted chemicals, and they claim that brewers, vintners, and distillers use additives to improve the color, the clarity, and the keeping quality of their drinks. Yet for every person who opposes the demon drink there is an ardent supporter of alcohol.

It is rare to find such a collection of emotions, warnings, hazards, and benefits surrounding a simple molecule. So what is special about this chemical? Can we balance its advantages against its disadvantages? The answer to these questions is to be found in a closer look at its chemistry.

Alcohol is also called ethyl alcohol or ethanol, which is the correct chemical name for this molecule. There are two ways in which alcohol is produced on a large scale: by the fermentation of sugars, or by the chemical reaction of water and ethylene. The former is agriculturally derived alcohol; the latter is often referred to as industrial alcohol. Although they are chemically identical, agriculturally derived alcohol is classed as drinkable, while industrial alcohol is made undrinkable by adding unpleasant chemicals. It is then popularly referred to as methylated spirits or meths for short.

The alcohol made by the fermentation of agricultural products is produced by the activity of fungi called yeasts. These grow by feeding on sugars, such as glucose, and as they do this they make alcohol, which for them is an unwanted by-product.

We can analyze the contents of an alcoholic brew and find that it contains lots of things apart from alcohol and water. For instance, a liter (about two of the traditional pints*) of the world-famous Irish drink, Guinness, in addition to providing you with 370 calories of energy, contains the following:

alcohol: 30 g carbohydrate: 30 g protein: 3 g phosphorus: 557 mg iron: 0.3 mg sodium: 25 mg potassium: 300 mg calcium: 54 mg magnesium: 133 mg thiamine (vitamin B1): 0.04 mg riboflavin (vitamin B2): 0.4 mg pyridoxine (vitamin B6): 0.6 mg nicotinic acid (niacin): 6 mg biotin: 0.01 mg folic acid: 0.07 mg

(*Many drink measures in this article are according to imperial measure, which is slightly different from American. For instance, a pint is 20 oz. and a gill is 4 oz.)

Clearly Guinness is also a good source of some essential minerals, and if we drink it regularly it will provide a significant fraction of our daily requirements of the B vitamins. The surprise of drinks such as Guinness is the large amount of potassium compared to sodium, and this is true of all beers. Most foods have much more sodium than potassium.* (*We often redress the balance when drinking by eating salted snacks.)

HOW IT AFFECTS THE BODY

Despite these dietary components, an alcoholic drink is not regarded as a food, a medicine, or a tonic, although in earlier times alcohol was advertised as all of these. Today we treat it mainly as a relaxant. Our body treats it as a poison. There are many ethical questions that alcohol raises which a knowledge of its chemistry cannot answer, but we can answer two key questions. Why does drinking make us feel good for a while, and then a few hours later make us feel so bad? Why do many people, such as women, native Americans, and Japanese, have to take special care because their tolerance of alcohol is low?

Alcohol does not occur as part of the complex chemistry going on inside the cells of the human body, but a little alcohol is produced naturally within our intestines by bacteria and yeasts which have enzymes that can turn carbohydrate into alcohol, and this alcohol gets into our bloodstream. Our liver has an enzyme called alcohol dehydrogenase (ADH) which gets rid of this unwanted chemical and converts the alcohol to acetaldehyde. This molecule is then turned into acetic acid by another enzyme, and the acetic acid is used in the so-called Krebs cycle of chemical reactions, by which its energy is extracted and it emerges as carbon dioxide.

The liver can deal with large amounts of alcohol, but it needs time to do so. If a person takes in too much alcohol at one session he may even die, and a lethal dose can be as little as 400 ml, the amount of alcohol in a liter bottle of spirits. A normal liver can process 12 ml (10 grams) of alcohol per hour. A glass of wine, which is about 12% alcohol, may provide this amount, as will half a pint of beer which is around 4% alcohol, and so will a tot, or shot, of spirits which is generally 40% alcohol. These measures are only rough guides because the amount of alcohol in wine, beer, and spirits can vary within quite wide margins. The quantity commonly referred to by those who give advice about drinking is the "unit," which is generally that quantity of a drink which will deliver 10 grams of alcohol. It is not a precise amount, only a guide, since it varies widely even among drinks of apparently the same type.

The effects of drinking alcohol can be seen in the table "EFFECTS OF ALCOHOL." This table cannot take into account all factors which determine the effect that alcohol will have, because this depends on a person's weight, the condition of the liver, and whether the alcohol is taken with a meal.

Alcohol starts to be absorbed the minute it enters our mouths, but most is absorbed from the stomach and the gut. Ten percent of the alcohol we take in is lost from our body without being digested. It is exhaled on our breath, sweated through our pores, or passed out in our urine. The other 90% is processed by the liver. The two chemicals which most affect our bodies when we drink are alcohol itself and acetaldehyde, which affect different organs in different ways:

Brain and Central Nervous System. Alcohol makes us feel happier, more at ease with people, and less inhibited about what we say and do. Technically alcohol is referred to as a depressant, but this does not mean that it makes us depressed. It means that it slows down the activity of the central nervous system so that messages take longer to travel along nerve fibers. We become more relaxed and overconfident in our abilities, but also slower to react, and our speech becomes slurred. Alcohol has this effect on the brain because it replaces water molecules around nerve cells, and this interferes with the movement of electrically charged atoms which are responsible for transmitting information along a nerve fiber. Alcohol also slows the movement of chemical messenger molecules which carry information from cell to cell.

Ears. These are the organs which give us our sense of balance. Alcohol changes the density of the tissue and fluid in the ear, and the more alcohol we take the bigger are the changes, until we lose our normal sense of balance. The result is that we sway and stagger, trying to compensate for the feeling that we are about to fall over.

Skin. Here it is the acetaldehyde which has an effect, dilating the blood vessels and making us feel hot. The dilation of blood vessels in the scalp and around the brain results eventually in a bad headache. Alcohol raises our pulse and blood pressure which increase the sensation of warmth. We can achieve the same effect if we take a shot of spirits on a cold day, but the comforting idea that people dying from exposure in the snow can be saved by a drink of brandy (carried by a St. Bernard dog, of course), is a myth. In fact, the alcohol would only serve to increase the loss of heat from their bodies.

Stomach. Men digest alcohol more quickly than women because they have more ADH in their stomachs and ADH converts alcohol to acetaldehyde. Consequently men can tolerate more alcohol than can women, because drink-for-drink, less alcohol gets into a man's blood stream from his stomach. Native Americans and Japanese have the same lower level of ADH as women. The male and female kidneys dispose of alcohol at the same rate, so that is not the reason for the difference between the sexes. Tests in the United States showed that when both men and women were given the same amount of alcohol by injection into their bloodstream there were no sex- related differences in behavior.

Liver. This is the main organ for removing alcohol, but as we have seen it does this slowly. Indeed, people have been known to fail breathalyzer tests 24 hours after their last drink. Alcohol also stimulates the breakdown of glycogen to glucose in the liver, depleting the body's immediate store of energy. Although alcohol is high in calories it does not satisfy your desire for food--indeed, it seems to stimulate it.

Kidneys. If you drink 250 ml of wine (about two glasses) you will lose at least 500 ml of water from your body as urine during the next two hours. Normally our kidneys will reabsorb and reuse water and are prompted to do so by a hormone called vasopressin, which is released by the pituitary gland at the base of the brain. Alcohol reduces the amount of vasopressin, and so the kidneys fail to recycle water, which then passes to the bladder and out of the body. The result is dehydration unless this fluid loss is replaced.

All these effects are the results of an immediate toxic reaction to alcohol. There are also longterm effects of taking alcohol over many years, such as impaired brain function and memory. Excess alcohol can lead to acute inflammation of the stomach, especially by the acetaldehyde formed, which is why for men one effect of alcohol can be a stomach ulcer.

HOW ALCOHOLIC DRINKS ARE MADE

Alcoholic drinks come in a large number of guises, but the main ones are beers, wines, and spirits. What distinguishes the last of these from the other two is the chemical process of distillation which concentrates and purifies the alcohol. Concentrating alcohol this way led to a whole new range of drinks.

Grapes, barley, corn, sugar cane, fruit, potatoes, and rice are all used to make alcoholic drinks. When the crop is harvested and the sugars of the carbohydrate component are released, they may be fermented into alcohol by acting as food for yeast. Yeast uses simple sugars in much the same way we do--as a source of energy--but unlike humans, who generate their energy with the help of oxygen from the air, the yeast generates its energy anaerobically, in other words without oxygen, and the product is alcohol.

Any source of sugary solution can be fermented, and in many countries there are drinks produced from a wide variety of fruit sugars. For example, in the United Kingdom, there is a large industry fermenting apple juice to make cider, and pear juice to make perry. There is even a cottage industry of homemade wine using soft fruit and wayside berries, such as blackberries and elderberries. Such fermented juice can be improved by adding ordinary sugar and the final strength of the drink may be as high as 13% alcohol.

Wine. Wine can be made simply by crushing grapes, squeezing out the juice and allowing it to ferment with the wild yeasts that are naturally present. This can be a hit-and-miss affair and does not always produce the desired result. It is better to add the right yeast to the grape juice, but even doing this does not always stop millions of liters of wine going to waste because rogue yeasts have outpaced the starter yeast which the vintner added. Some rogue yeasts even produce toxins which can kill the commercial starter yeasts.

Not all wild yeasts are bad; some impart a new flavor to the wine and are cultured and added to the crushed grape. Winemakers jealously guard their strains of yeast. The preferred yeast for wine is Saccharomyces ellipsoideus, and unwanted bacteria are kept down by using sulphur dioxide, which is added as its solution in water or as sodium sulfite which dissolves in water and forms sulfur dioxide. In earlier times "sulfiting" was done simply by burning sulfur near the vat of grape juice.

There are thousands of wines which divide first into red, white, and rose, then into region. White wines are made from grape juice which has been separated from the grape skins. Red wine is fermented with the skins, and their color chemicals are extracted into the alcohol solution. This also extracts tannins and other compounds which add flavor and help the wine to keep better. The red dye compounds from the skins can be extracted more quickly by heating to 122 degrees F. Rose wines are produced from a blend of white and red grapes.

The amount of alcohol in wines can vary between 5% and 13%, which is about the maximum concentration that a yeast can survive. Most have about 10% to 12%. If the content exceeds 13%, the product must include added alcohol, and these are called fortified wines, of which the best known are sherry, vermouth, and port with about 15% alcohol. These also have added sugar (vermouths have added herbs as well), and they are left to stand in casks, from the wood of which they extract more chemicals.

Beer. All that was needed to discover wine was to crush the grapes to release the juice, and the wild yeast spores on the skins would do the fermenting. On the other hand, brewing beer is such a complex process that John Postgate in his book MICROBES AND MAN says that it is a wonder that it was ever discovered. Yet the first written accounts of beer date from the Egypt of the 1st Dynasty, around 3,000 BC.

About a thousand years earlier, the ancient Babylonians are thought to have brewed ale, rather than beer (which requires hops to be added to make it bitter). It is rather remarkable that ale was first brewed 6,000 years ago when we consider the chemistry involved. Ale is produced from fermented barley, yet the starch in cereal grains cannot be fermented by yeasts, which need simple sugars to work on. The first step in brewing ale is to steep the barley in water for a day or two and then leave it in a warm, damp room for a few more days so that it will germinate. This process is called malting. The grain sprouts develop enzymes which break down the starch into simple sugars. The malted barley is next heated to stop the sprouting and steeped in water to soak out the sugars and other plant chemicals on which the yeast can grow. The resulting solution is sieved and called "wort."

To make beer the wort is then boiled with hops, which imparts flavor and releases preservative chemicals that prevent the growth of bacteria which might spoil the beer. Finally, the yeast Saccharomyces cerevisiae is put in, and the whole lot is allowed to ferment for a week or so. As the yeast multiplies it produces not only alcohol but also a whole cocktail of organic molecules which give the beer its flavor. When the fermentation is over, the brew is processed to remove sediment, clarified, and packaged for distribution.

There are hundreds of brands of beer, although only a few types, which divide roughly into top fermented beers, such as the traditional mild, bitter, pale ale, and stout, and the bottom- fermented beers, such as pilsner and lager. Ale is made by fermenting malted barley wort with a top-floating yeast which cannot ferment all the malt sugars and which works best at a temperature above 50 degrees F. Lager is made from less strongly malted barley and is fermented with a yeast (Saccharomyces carlsbergensis) which works at the bottom of the wort, and which can ferment all the malt sugars. This yeast will continue to ferment down to 32 degrees F. So-called "lite" beers and lagers have been allowed to ferment until all the sugars are turned to alcohol. Their name is misleading because they are only slightly less calorific than normal beers and lagers.

Spirits. To make drinks with a high level of alcohol it is necessary to use a still. Distillation was discovered by the ancient Romans over 2,000 years ago, and brought to a fine art by the monks of the Middle Ages. Distilling wine drives off the alcohol, and when the vapors, or "spirits," are cooled and collected you have a product which is mainly alcohol. In fact, methanol distills off first because this boils at 149 degrees F, and should be discarded, then the alcohol comes off, boiling at 172 degrees F. The vapor that condenses from a still also contains a lot of water, but a second and maybe a third distillation will reduce this until we collect almost pure alcohol. Distillation alone cannot remove the last traces of water because water and alcohol form a so-called azeotropic mixture, which means they distill over together once a certain composition is reached. This composition is about 95% ethanol, 5% water. To get absolutely pure alcohol, ways other than distillation are needed to remove the water, but such alcohol is never required for making drinks.

Through the centuries distilled alcohol has been a part of the medical pharmacopeia. The first distilled alcohol was known as aqua vita, or water of life, and was valued for its restorative properties. Spirits were also used by surgeons as an early form of anesthetic and to clean wounds. Alcohol was used to wipe the skin before injections because it is a good antiseptic when pure. For the same reason it is also a good preservative.

What distinguishes the different kinds of spirits are the tiny amounts of other volatiles which distill with the alcohol. In this way, we have brandy (which comes from wine), whisky (which, like beer, is made from fermented barley), rum (from fermented molasses), and bourbon (from fermented corn). Vodka is made from fermented grain or potatoes and is the purest drink of all because it is passed through a charcoal filter to remove everything except the alcohol. This is why it is almost tasteless.

Gin is made from fermented grain alcohol and flavored by a second and even third distillation from a blend of herbs, fruits, and berries. These so-called botanicals are a secret blend of up to ten fruits, herbs, and spices which must include juniper, this being the essential component which identifies a drink as gin. Other botanicals may be coriander, angelica, orris root, almonds, cassia bark, licorice, orange and lemon peel, cardamom, cinnamon, and nutmeg.

THE RISKS AND BENEFITS

Alcohol can do serious harm to the human body. The health risks that a heavy drinker faces are broken bones, obesity, addiction, ulcers, cirrhosis of the liver, brain damage, a particularly nasty form of heart disease called cardiomyopathy, and possibly even cancer of the esophagus. The effects on the liver are complex and still not clearly understood. They stem from changes in the levels of co-factors, which are chemicals necessary to the action of enzymes. The outcome is that the oxidation of fatty acids is impaired in the mitochondria, the structures in the cells that produce energy, and more fats are synthesized. These fats accumulate in the liver to produce what is known as fatty liver, a symptom of alcoholism. Cirrhosis of the liver is a condition exacerbated by the long-term abuse of alcohol. It was once thought to be caused by it, but this seems unlikely. Cirrhosis was seen as a toxic response in which normal tissue is replaced by collagen (fibrous tissue). As a consequence the liver functions less efficiently.

Alcohol can be regarded as a form of food. A unit of alcohol (10 grams) provides us with about 70 calories of energy. The recommended maximum intake for a man is 21 units of alcohol a week, and this will provide about 1,400 calories of his energy intake. For a woman the recommended amount is 14 units of alcohol, which will provide around 1,000 calories. While these are not excessive amounts they nevertheless must be taken into account when planning a diet. Alcohol accounts for about 10% of the food intake of adults in the United States and Europe. It was once considered such a convenient way of providing energy that it used to be added to intravenous drips as a supplement.

As a food, alcohol has some disadvantages. It cannot supply energy in the same way as carbohydrates, so it does little to help us work or exercise, but it can supply excess calories that lead to weight gain and can be a very expensive form of food. A pint of beer will provide between 140 and 210 calories depending on whether it is mild, bitter, keg, lager, or stout. Draught mild has the fewest calories while stouts have the most. The calorie content of wines and ciders depends also on the sugars they contain, and that can be judged on whether they are labeled sweet, medium, or dry. Four fluid ounces of wine (a normal glass) will be about 110 calories if sweet, but 75 if dry. It makes no difference whether the wine is red or white. A glass of sherry is about 50 ml and provides between 55 (dry) and 65 (sweet) calories. A single measure of spirits or liqueur is about 25 ml (a sixth of a gill) and provides between 50 and 75 calories. Whisky and gin are about 50; liqueurs such as cherry brandy and Cointreau are nearer 75.

Alcoholic drinks such as beer and wine also provide other dietary nutrients, but spirits and other distilled drinks lack these. A pint of beer contains about 50 mg of calcium and 0.1 mg of iron, while a glass of wine has only about 10 mg of calcium but up to 1 mg of iron. Cider has almost 3 mg of iron per pint. Beer is also a source of the B vitamins, although wines have less of them. These vitamins come from the yeast. No alcoholic drink provides vitamins A, C, or D.

The benefits of alcohol are varied. Some are well known, such as a nightcap of a glass of beer, or a shot of whisky, to help get off to sleep. However, it may not be a good night's sleep, because alcohol appears to deprive us of a key type of sleep, the early sleep in which we dream. Continued loss of this essential sleep may be the reason why very heavy drinkers eventually suffer the hallucinations traditionally known as the "DTs" (delirium tremens), although these are more likely to strike as part of the symptoms of alcohol withdrawal.

Moderate drinkers, those who take two or three units of alcohol a day, suffer less coronary heart disease and have lower cholesterol levels. Drink may be beneficial for the heart but only in moderation. Men who drink more than the equivalent of six pints of beer a day (12 units) are twice as likely to suffer a sudden heart attack as nondrinkers, according to Professor Gerry Shaper of the Royal Free Hospital in London who carried out an eight-year study of over 7,500 middle-aged men. Each year about 25 died this way, and two-thirds of these were heavy drinkers.

Studies of the life style of French farmers supports drinking as beneficial, as revealed in the leading medical journal LANCET in 1992. Dr. Serge Renaud of the National Institute of Health and Medical Research in Lyons, France, believes that French farmers are less prone to coronary heart disease, despite a diet rich in animal fats, because of their relatively high consumption of alcohol in the form of red wine. Two glasses a day is the recommended amount. Red wine is not a medicine, and it will not cure or relieve heart problems that are already present. If there is any value in drinking red wine, it lies in its ability to prevent heart disease. This message of the benefits of red wine increased sales by over 44% in the United States when it was announced in 1992. A group at Kaiser Permanente Medical Center in Oakland, California, claimed that drinkers of white wine were also less likely to suffer coronary heart disease. Whether it is the alcohol itself or phenolic compounds in the wine that are responsible is a matter of debate. The antioxidant behavior of the phenolics may slow down plaque formation from low-density lipoproteins--the "bad" form of cholesterol.

Not only do drinkers appear to have lower cholesterol levels and have less coronary heart disease, but they also get fewer colds. That was the conclusion of the final research project carried out by the now-defunct Common Cold Unit at Salisbury, England. Not every common cold virus we catch leads to a cold. Between four and ten viruses infect us every year, but only half of these end up as bad colds--for the rest we either have existing antibodies against the virus, or we can shake it off easily. Nor can you stop a cold with the popular cure of hot whisky and lemon; all this does is to make the misery a bit more bearable.

However it works its magic, alcohol certainly seems to reward many of its moderate users: those who drink two units of alcohol a day catch half the number of colds that non-drinkers suffer. This does not apply to smokers though; smoking cancels out the protection against colds which comes with drinking.

* * *

EFFECTS OF ALCOHOL Units: 2 Drinks Beer (2): 1 pint Wine (3): 2 glasses Spirits (3): 2 singles Blood Alcohol Level: .03 Effect (1): feeling of well-being

Units: 3 Drinks Beer (2): 1.5 pints Wine (3): 3 glasses Spirits (3): 3 singles Blood Alcohol Level: .05 Effect (1): lack of inhibitions

Units: 5 Drinks Beer (2): 2.5 pints Wine (3): 5 glasses Spirits (3): 5 singles Blood Alcohol Level: .08 Effect (1): unfit to drive

Units: 6 Drinks Beer (2): 3 pints Wine (3): 1 bottle Spirits (3): 6 singles Blood Alcohol Level: .10 Effect (1): unsteady on feet

Units: 10 Drinks Beer (2): 5 pints Wine (3): 1 liter Spirits (3): 10 singles Blood Alcohol Level: .15 Effect (1): slurring speech

Units: 12 Drinks Beer (2): 6 pints Wine (3): 2 bottles Spirits (3): .5 bottle Blood Alcohol Level: .20 Effect (1): drowsy & confused

Units: 18 Drinks Beer (2): 9 pints Wine (3): 3 bottles Spirits (3): .75 bottle Blood Alcohol Level: .30 Effect (1): drunken stupor

Units: 24 Drinks Beer (2): 12 pints Wine (3): 4 bottles Spirits (3): 1 bottle Blood Alcohol Level: .40 Effect (1): dead drunk

1. On the average man. For a woman the same effects may be experienced with about two-thirds the amount of alcohol that a man needs, assuming they are the same weight.

2. Imperial pint equal to 20 oz.

3. Sold in 700 ml bottle.