Food Value

A food may be defined as a substance whose dominant property in the body is to build up the tissues or to yield energy. Protein is our reliance for the building or reconstruction of tissue; carbohydrates and fats are restricted to furnishing energy. It is evident, from its chemical constitution, that alcohol has no power to build tissue. We might inquire, then, into its value in the production of energy.

To What Extent Can Alcohol be Oxidized in the Body? - God-dard administered 16 gm. of absolute alcohol, properly diluted, to a fasting dog weighing 12.4 kilos (about 25 pounds), and found that all the alcohol had disappeared in five and one-half hours, and that only about 5 per cent. of it had been recovered, some in the breath and some in the urine, i. e., 95 per cent. had been completely oxidized. If humans oxidize alcohol at the same rate, a man of 160 pounds could dispose of - i. e., burn up and utilize for energy - 6 ounces of whisky given at one dose - about three-fourths of a tumblerful, or enough to produce drunkenness. To test this Atwater and Benedict treated healthy men with six 1-ounce doses given with food at intervals during the day. It was completely oxidized, except for the small amount of 1.9 per cent. that was recovered from the breath and urine. Alcohol in any ordinary amounts is, therefore, practically completely burned up by the body. In Goddard's experiments larger amounts than mentioned above resulted in the appearance in the breath and urine of aldehyde and other incompletely oxidized products of alcohol.

Can Alcohol Directly Replace Fats in the Food? - Atwater and Benedict placed a man on a fixed diet of mixed character. During thirteen days of resting he increased in weight an average of 33.7 gm. daily, i. e., stored up that much surplus. When for ten days 72 gm. alcohol, as in 6 ounces of whisky or a quart of claret, was given each day, and its equivalent in fat deducted from the daily dietary, the average gain was 34.1 gm. daily. It was not alcohol that was stored up, but fat, the alcohol being burned up first to supply the energy, and a corresponding amount of fat being spared to be stored up. There was no increase in the intake of oxygen or the output of Co2 other than that normally following the ingestion of food.

These same experimenters, Atwater and Benedict, also studied the metabolism of a man who was fed for alternating periods of five days on a definite mixed diet, and on the same diet but with 72 gm. of alcohol replacing an isocaloric amount of fat in the daily allowance. During the first two periods of five days the man was at rest, and during two other five-day periods he was at hard work. They found that, both during the rest periods and the hard-work periods, the total metabolism was practically the same on the alcohol dietary as on that containing fat. Therefore alcohol supplied the energy for rest or for work just as well as fat did, and prevented drawing upon the tissues.

We might refer also to the experiments of Hellsten and of Schnyder and Dubois, and of the German government (see below), which established the energy-producing value of alcohol when the regular food-supply was deficient. The experiments of Rosemann (1901) on himself over a period of thirty-seven days,.

and of Neumann (1901) on dogs in two periods of twenty-five and thirty-six days, give also some exact data as to the ability of alcohol to prevent tissue waste and to replace fat in the dietary. One of Neumann's experiments was as follows: For five days he kept dogs in nitrogen equilibrium (that is, on a mixed diet whose daily nitrogen was the same in amount as the daily excretion of N). He then for four days gave the same diet, but with half its fat omitted; the nitrogen excretion increased, showing that there was more protein destruction, i. e., the proteins were being drawn upon to supply the energy that the fat had supplied. Then alcohol, in amount chemically equivalent to the omitted fat, was added to the food, and the nitrogen equilibrium again became established. Therefore alcohol was able to spare the proteins in the same way as the fat. But Neumann went further, and not only gave the alcohol, but also replaced the omitted fat, and the nitrogen excreted became less than that ingested, i. e., there was less protein destruction than with either alcohol or fat alone, and protein was being stored up, so that alcohol performed the function of fat in sparing protein even when the fat in the food was sufficient. Lastly, Neumann omitted both the fat and the alcohol, and the nitrogen excretion again greatly exceeded that taken in with the food, that is, there was excessive protein destruction. We might sum up the teachings of these experiments as follows: When fat in the food is deficient, alcohol can entirely compensate for the deficiency, at least for a short period; it yields the energy that fat would yield, and so spares protein and prevents tissue waste. When alcohol and fat are administered together in quantities above the needs of the body, the alcohol is the more easily utilized to supply energy, so that the fat is spared and stored up in the body.

(in metabolism experiments with alcohol it has been found that there is usually a loss in protein for the first three or four days until tolerance is established; but if the alcohol is begun in very small doses, the primary protein destruction does not occur; and in those accustomed to alcohol, even larger quantities of alcoholic drinks result in no primary nitrogen loss, even in fever

Ott.)

Can Alcohol Directly Replace Carbohydrates in the Food? - To test this, At water and Benedict studied the metabolism of a man at rest during five-day periods. During the first period he was on a fixed diet, without sugar, representing 2290 absorbable calories. He gained very slightly in weight, the daily calories of metabolism being 2176, and the calories of retention being 77. During the second period he took the same diet plus 72 gm. of alcohol (500 calories), and gained more in weight; the calories of metabolism being 2258 and those of retention 589. During the third period he took the same diet with the exclusion of the alcohol, and the substitution therefor of 130 gm. of sugar (515 calories); the calories of metabolism being 2272 and those of retention 562, practically the same as with the alcohol. There was no essential difference in the intake of oxygen or output of carbon dioxide, except that associated with the taking of any food.

Absorbable Calories

Calories of Metabolism

Calories of

Retention in

Weight

Fixed diet........................

2290

2176

77

Fixed diet + 72 gm. alcohol.

2290 + 500

2258

589

Fixed diet + 130 gm. sugar ..

2290 + 515

2272

562

Rosenfeld (1900), in an eleven-day experiment with a nitrogen equilibrium diet, found that 120 gm. of alcohol caused a nitrogen saving of 17 per cent., and that a corresponding sparing of nitrogen occurred from equivalent amounts of cane-sugar. Durig (1913) gave abundance of sugar with and without alcohol, and found that, despite the surfeit of sugar, the alcohol was the first to be burned for the liberation of energy. Hammett found no change in the nitrogen partition of the urine when alcohol was substituted for sugar in a mixed diet. From these data we may conclude that alcohol in moderate quantities given with a mixed diet can replace equivalent amounts of carbohydrates in the food, at least for a short period. It is noteworthy, however, that Higgins, Peabody, and Fitz found alcohol completely incapable of checking an acidosis brought on by carbohydrate starvation, though the acidosis promptly disappeared on the administration of carbohydrates.