Respecting the effect of alcohol on the process of digestion a good deal has been written, both as to the favourable and the detrimental results produced; but the consensus of modern opinion seems to be distinctly against the view that for the ordinary healthy individual there is, on the whole, any particular benefit to be obtained by the use of alcohol as a dietetic beverage. Some beneficial action there may be, but it is liable to be set off by undesirable consequences in other parts of the system. It is only in certain acute diseases that any desirable effects produced by alcohol on the stomach are worth obtaining.

1 Pfluger's Archiv, 1899, 79, 597.

Certainly the common notion that alcohol in moderate quantity is a useful aid to gastric digestion does not receive very much support from digestion-experiments made in vitro. Some of the earlier of such experiments, carried out by Sir W. Roberts1 more than a quarter of a century ago, may usefully be quoted. The digestion-mixture studied was composed of 2 grams of beef-fibre, 1 c.c. of glycerine extract of pepsin, hydrochloric acid sufficient to give 015 per cent. of HC1, and varying proportions of alcoholic liquors, the whole being made up with water to a volume of 100 c.c. The time in which the digestion of the beef was completed was compared with the time (one hundred minutes) required without alcohol. The results may be summarised as follows: -

Roberts's experiments on peptic digestion.

The 'spirits' used comprised proof spirit (plain), brandy, whisky, and gin.

Roberts considered that the wines and malt liquors contained some retarding agent besides alcohol, as the effect produced on the digestion was out of proportion to the amount of alcohol present.

If the total gastric charge of food is taken as 2 lb., 20 per cent. of this would be about 6 1/2 oz., so that according to these results less than a glass of beer exercises a perceptible, though not a considerable, effect upon peptic digestion.

Coming to more recent work, Chittenden's experiments may be quoted. This observer found that when the percentage of alcohol in the digestive mixture used was as low as 1 or 2 per cent. there was sometimes a slight acceleration of the rate of digestion. When, however, the proportion of alcohol was raised, retardation or inhibition of digestive action occurred, though this was ordinarily not very pronounced until the digestive mixture contained 5 to 10 per cent. of alcohol, or more. Further, with a weak gastric juice, where the amount of ferment present is small and the digestive action consequently slow, or where the proteid material is difficult of digestion, the retarding effect of a given percentage of alcohol is far greater than where the digestive fluid is more active. It may be noted, in passing, that a concentration of 10 per cent. of alcohol can rarely, if ever, be present in the stomach of a living man for more than a few seconds.

1 " Collected Contributions on Digestion and Diet," 1891.

The foregoing experiments do not, of course, take into account all the factors concerned in actual digestion in corpore. In addition to the effects of alcohol upon the action of the enzymes as just described, its influence upon the secretion of the digestive juices, and upon the churning movements of the stomach which normally aid digestion, have also to be considered.

There is no doubt that alcohol placed in the mouth does, like other sapid fluids, increase the flow of saliva, but this action is of no very great importance. There is also no doubt that on reaching the stomach alcohol evokes a considerable secretion of a kind of gastric juice. This juice, however, differs from the normal gastric juice, inasmuch as it is deficient in pepsin, though it contains the normal amount of hydrochloric acid. In fact, whatever pepsin this juice contains is what has been washed out of the cells; alcohol apparently causes no fresh secretion of pepsin. Hence the increased supply of juice is of no particular value in improving the digestion, although, on the other hand, there is no evidence that it has any detrimental effect. The flow of the other digestive juices - the pancreatic juice and the bile - is also stated to be increased by alcohol, and this may be in part due to some action on the stomach, since it is known that an increase of gastric secretion often leads to augmented activity of the pancreas. As tested by experiments on dogs, the amount of increased gastric secretion is greatest when relatively small doses are given, such as produce in the stomach a concentration not greater than 10 per cent. Larger proportions lead to the formation of much mucus, with less total juice.

As Roberts's experiments and those of Chittenden show, the peptonising power of the gastric juice is not much affected by small doses of (plain) alcohol, but is distinctly retarded by large doses. Some authorities have considered that the effects on pancreatic digestion are more favourable, and even that alcohol accelerates the digestion of fats; but there is evidence to show that as tested in vitro the enzymes of the pancreas are yet more susceptible to the action of alcohol than are those of the stomach. In concentrations as low as 2 to 3 per cent. alcohol may retard the digestion of albuminous substances. But be that as it may, the probability is that, in the organism, alcohol reaches the intestine in such relatively small proportions and in such a low degree of concentration, and moreover is so rapidly absorbed there, that its action on pancreatic digestion is of comparatively small importance.

As regards the churning motion, it is often stated that alcohol "promotes greater activity in the muscular layers of the stomach,"1 and thus tends to accelerate digestion. It does not appear, however, that this increased activity can be accepted as satisfactorily demonstrated, and some observers have failed to obtain any confirmation of the statement. Carlson,2 for instance, saw no increase of churning movement when diluted alcohol, brandy, and wines were introduced into a man's stomach through a fistula; but on the contrary, the rhythmical movements and the bracing of the muscular coats, which are associated with hunger, were arrested. Doses of 50-100 c.c. of 10 per cent. alcohol sufficed to stay the hunger-contractions for two hours, and 200 c.c. of beer had the same effect for half an hour to an hour. Chittenden,3 in experiments on dogs, did not find that the presence of alcohol materially lessened the time during which food remained in the stomach. There appears, indeed, to be at present no good evidence that gastric movement is increased by alcohol, whilst some forms of stomach-contraction are even arrested by it. Horsley and Sturge consider that lessened vigour of the muscular movements of the stomach is a consequence of alcohol depressing the nervous system, since the nerves which control the muscles are enfeebled.4

Similarly, there seems at present to be no trustworthy evidence that moderate doses of alcohol have any important effect, one way or the other, upon the process of absorption of the digested foodstuffs into the blood. In general, it may be said that apart from its taste and its tendency to increase gastric secretion and mucus, alcohol itself, in moderate doses, has not been proved to affect the digestive organs to any appreciable degree. On the other hand, there is a consensus of opinion that some of the alcoholic beverages may be more deleterious than others. Some wines, for instance, do not "agree" with certain people, though other persons can take them without digestive ill-effects. The extractive matters - tannins, acids, sugars, and other solids - as also the volatile secondary

1 Encycl. Brit., article " Alcohol."

2 Amer. J. Physiol, 1913, 32, 252.

3 " Physiological Aspects of Liquor Problem," 1, 294. Boston, 1903.

4 " Alcohol and the Human Body," p. 164.

N N constituents, namely, esters, higher alcohols, aldehydes, and acids, have been suggested as the possible causes of disturbed digestion in these cases; but at present there is nothing actually and definitely known about the effects produced by these substances.