THE METABOLISM OF VEGETARIANS AS COMPARED WITH THE METABOLISM OF NON-VEGETARIANS OF LIKE WEIGHT AND HEIGHT. BY FRANCIS G. BENEDICT AiVD PAUL ROTH. (From the Nutrition Laboratory of the Carnegie Institution of Washington, Boston, and the Battle Creek Sanitarium, Battle Creek.) (Received for publication, January 15, 1915.) Perhaps no special dietetic regime is more successful in attract- ing adherents and holding them than is that bf vegetarianism. While the modern conception of the word “vegetarianism” is by no means as strictly applied to the exclusive use of vegetables as was formerly the case, and we have at the present time the lacto-vegetarians and the ovo-vegetarians, nevertheless there are a considerable number of individuals who regularly confine themselves to a strictly vegetarian diet. Large groups of people, particularly in foreign countries, are by long custom vegetarians. In this study, however, we are specialIy concerned with a considerable number of individuals who, notwithstanding the fact that they live among people partaking of an ordinary mixed diet, yet adhere closely to a vegetarian diet. This adherence to a vegetarian diet may be clue to any one of several causes: First, to environment, heredity, training, or the habit of the household and parents; second, to a religious belief, in which the use of flesh for food is pros&ibed; third, as the result of some dietetic alteration incidental to the treatment of disease and a subsequent adherence to the vege- tarian diet; or finally, for physiologic or biologic reasons, in the belief that a non-flesh dietary is the natural or physiologic diet for human beings as well as other primates. In the discussion of the supposed benefits of vegetarianism, considerable stress has been laid upon the remarkable endurance’ 1 I. Fisher: Yale Med. Jour., xiii, p. 205, 1907. See also Ioteyko and Kipiani: Rev. de la Sot. scient. d’hyg. alimentaire, iii, p. 114, 1906. 231 by guest on May 3, 2019 http://www.jbc.org/ Downloaded from
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THE METABOLISM OF VEGETARIANS AS COMPARED WITH THE METABOLISM OF NON-VEGETARIANS
OF LIKE WEIGHT AND HEIGHT.
BY FRANCIS G. BENEDICT AiVD PAUL ROTH. (From the Nutrition Laboratory of the Carnegie Institution of Washington,
Boston, and the Battle Creek Sanitarium, Battle Creek.)
(Received for publication, January 15, 1915.)
Perhaps no special dietetic regime is more successful in attract- ing adherents and holding them than is that bf vegetarianism. While the modern conception of the word “vegetarianism” is by no means as strictly applied to the exclusive use of vegetables as was formerly the case, and we have at the present time the lacto-vegetarians and the ovo-vegetarians, nevertheless there are a considerable number of individuals who regularly confine themselves to a strictly vegetarian diet.
Large groups of people, particularly in foreign countries, are by long custom vegetarians. In this study, however, we are specialIy concerned with a considerable number of individuals who, notwithstanding the fact that they live among people partaking of an ordinary mixed diet, yet adhere closely to a vegetarian diet. This adherence to a vegetarian diet may be clue to any one of several causes: First, to environment, heredity, training, or the habit of the household and parents; second, to a religious belief, in which the use of flesh for food is pros&ibed; third, as the result of some dietetic alteration incidental to the treatment of disease and a subsequent adherence to the vege- tarian diet; or finally, for physiologic or biologic reasons, in the belief that a non-flesh dietary is the natural or physiologic diet for human beings as well as other primates.
In the discussion of the supposed benefits of vegetarianism, considerable stress has been laid upon the remarkable endurance’
1 I. Fisher: Yale Med. Jour., xiii, p. 205, 1907. See also Ioteyko and Kipiani: Rev. de la Sot. scient. d’hyg. alimentaire, iii, p. 114, 1906.
apparently shown by vegetarians over flesh eaters, the statements being made that the vegetarians live upon a distinctly lower metabolic plane, are not so highly stimulated as the flesh eaters, have a lower blood pressure, and, in general, that the metabolic activities are on a lower level.
Fortunately, while it is wholly impossible to measure accurately and scientifically many of the indices of benefits or lack of benefits commonly cited by individuals, it is perfectly feasible to measure the metabolic plane by studying the respiratory exchange.2 Thanks to the kindness and interest of Dr. J. H. Kellogg of the Battle Creek Sanitarium, Battle Creek, Michigan, we were en- abled to make a series of observations on both men and women. vegetarian subjects, all of whom may be definitely classified as normal individuals. The greater number of the subjects were members of the staff of the Sanitarium. These individuals had been meat abstainers for varying lengths of time, the periods being stated in the list given below. It is safe to state that those designated in this list as strict vegetarians probably did not eat meat of any kind more than two or three times a year.
Men.
0. N. A. B. N. C. V. E. H.
B. K.
W. B.
F. E. M. Dr. P. R.
E. H. T. E. J. W. L. H. W.
T. H. Y.
Strict vegetarian for 6 mos. Strict vegetarian for at least 10 yrs. Strict vegetarian for 1 yr. Practically a vegetarian for 2 yrs. Used meat probably
once a month on the average. Vegetarian for 5 to 6 yrs. Has eaten meat not oftener
than 2 or 3 times a yr. during that time. Strict vegetarian for 13 yrs. Strict vegetarian for many yrs., andpracticallyall his life. Strict vegetarian for 8 mos. Strict vegetarian for over 20 yrs. Except for a short period of 3 to 4 wks. (several yrs. ago)
has been practically always a vegetarian. For several yrs. before the test had not eaten meat oftener than once a mo.
Strict vegetarian for over 5 yrs.
* For a report of the most important study of the respiratory exchange of vegetarians thus far made, see W. Caspari: Arch. f. d. ges. Physiol., cix, p. 473, 1905.
Strict vegetarian for 2 yrs. Vegetarian diet for 3 mos. only. Strict vegetarian for 2; yrs. Very seldom ate meat at any time, practically none for
10 yrs.; none for 21 yrs. before test. Strict vegetarian for 20 yrs., with the use of meat at very
infrequent intervals, not more than 2 or 3 times a yr. Strict vegetarian for 2 yrs. Strict vegetarian for 6 wks. only. Strict vegetarian for 1 yr.; ate meat only on rare occasions. Vegetarian for 5 or 6 yrs. Had eaten meat not oftener
than 2 or 3 times a yr. during that time. Strict vegetarian for 1 yr. Practically a life vegetarian. Had eaten no meat for
14 yrs.
The unit respiration apparatus was used for this study, all due precautions being taken as to muscular repose, absence of food in the stomach, and a non-febrile temperature; every effort was made to approximate the simplest and most perfect physiological condition. Observations were carried out with some subjects on but one or two days, but frequently they were made on several days. All recorded values were derived from not less than two satisfactorily agreeing experimental periods.
In comparing the results, it is obviously improper to obtain simply a grand average for aIlSthe experiments with vegetarians and compare this with an average for the experiments with non- vegetarians. We have, therefore, adopted the plan of comparing the vegetarians with control individuals living on a mixed diet and of the same sex and approximately the same weight and height. The ages of our subjects ranged between 20 and 40 years, and we have only occasionally to deal with the possible influence of greater age; these cases will be specially noted.
In the majority of instances it was not possible to select a nor- mal individual comparing exactly in height and body weight with a vegetarian; and, indeed, it would be wholly erroneous to select any one individual for this comparison. We have, there- fore, divided the comparisons into groups, using for each group several non-vegetarian individuals having approximately the same height and weight. Unfortunately the number of vegetarians studied, while considerably greater than ever before observed,
G’omparison of the heat production of vegetarians and non-vegetarians. (Experiments with men.)
GBCUP hi-m SUB.iECT
.I
GROUP I Vegetarian
F. E. M ............. Non-vegetarian
F. A. R .............. GROCP II
Vegetarian E. H. T ..............
Non-vegetarian F. P. R .............. D. M ................. M . J. S ...............
GROUP III Vegetarian
L. H. W .............. B. K .................
Non-vegetarian 0’. G. J .............. L.E.E.. ............ Dr. S ................ D. J. M .............. H. F. T ..............
GROUP IV Vegetarian
T.H.Y.. ............ Non-vegetarian
A. L .................. H. B. R .............. J. B. T ............... W. F. rj ............... E. T. W’. .............. P. I’. J ................ A. G. E ...............
GROUP T:
Vegetarian IV. B. L ...............
Non-vegetarian H. H. A ............... S. A. R ................ H.B.R.. .............
h’on-vegetarian I 1.A.F ..__.__......... 1 54.9 J. II. . . . . 46.3
GROUP X Vegetarian
V. E. II . .’ 49.3 Non-vegetarian
J. J. G . . . . ..__........’ 50.2 T. M. C.. . . . . . . . . / 48.5
I ! Total Per km.
cm. cd. cd.
I
164
167 160
171
171 169 173 169
1341
1616 1455
1545
1539 1531
‘1522 1421 25.8 798
179
175 174
1510
1453 1541
155 1158
156 1612 154 1223
163 1365
164 1425 165 / 1292
24.3 ~
28.3 27.1
27.9 863
27 .O 844 26.9 841 27.1 846
831
29.8 893
27.0 826 29.5 896
23.2 693
29.4 906 26.4 769
27.7 822
28.4 848 26.6 788
is still too small to permit grouping, and, as a rule, only one vegetarian is used in each comparison. For this reason, we dis- tinctly decline to draw conclusions from the individual compari- sons, as they can be intelligently drawn only from the general picture.
The comparison of the male subjects is given in Table I. The subjects are here divided into ten groups, corresponding to
eleven vegetarians, as, except in the case of Group III, no two can properly be classified in a single group. In choosing individuals living on a mixed diet for comparison, the sole bases for selection have been those of body weight and body height. In other words, every attempt has been made to secure a purely objective compari- son. An examination of this table shows that there is no strik- ing uniformity in the results, the metabolism of the vegetarians being at times somewhat lower than that of the control. Occa- sionally the vegetarians show a higher metabolic plane than any of the control subjects. On the other hand, the vegetarians Dr. P. R., Group VI, and E. J. W.,3 Group IX, show a noticeably lower metabolism than either of the controls with whom they are compared.
Believing that a comparison of the average metabolism of each group of controls with the average metabolism of the vegetarian in the same group will give a better picture, the averages have been brought together in Table II. Here for the first time we are permitted to obtain an average ,of all the controls with an average of all the vegetarians, since we are now comparing vege- tarians with control individuals of approximately the same body weight and height. Accordingly in these final summary tables we may compare simply the heat per kgm. of body weight and’ per square meter of body surface.
In the averages for the ten groups, the vegetarians show a higher metabolism than the controls in four cases. In the grand average the metabolism of the vegetarians (25.5 calories per kgm.) is approximately 4 per cent lower than that of the non-vegetarians (26.4 calories per kgm.)‘. The same small difference is found when the comparison is mide on t,he basis of’ heat per square meter of body surface.
3 The extraordinarily low values found with E. J. W. may in part be explained by the fact that he was the oldest man entering info this com- parison, being 58 years old, and evidence has accumulated to show that age affects materially the intensity of the metabolism. Singularly enough, while the oldest woman entering into the comparison (Mrs. E.B.) is 53 years old, there is no noticeable difference in her metabolism over that of the other women vegetarians, although it is possibly of significance that she had been a vegetarian but 3 months. In both sets of comparisons the effort has been made to select controls that would be least affected by differences in age.
From a cursory examination of all the available data in this laboratory for normal individuals, it early became apparent that the metabolism of men may not properly be compared directly with that of women, and hence in this critical study of the metab- olism of vegetarians we have felt it important to compare men with men and women with women. The values found for the women vegetarians and their controls are given in nine groups in Table III. In only two groups, namely, Groups I and VIII,
TABLE 11.
Summary of comparison of vegetarians and non-vegetarians. (Experiments with men.) _~~-. -.
I HEAT- PBCD~~CN PER 24 HB~.
I (COMPUTED)
vegetarians - I-
I ml. I ..................
II .................. III. ................. IV. ................. v ..................
VI. ................. VII. .................
VIII. ................. IX. ................. X ..................
is it possible to include more than one vegetarian. An examination of the data shows that here again there is no striking uniformity in the direction of the values. Thus the two individuals, Dr. M. D. and Miss 0. A. in Group I, had a measurably higher metab- olism than the control, Miss H. H. Similarly, Miss C. 2. in Group II, had a considerably higher metabolism than any one of the three controls with whom she is compared. On the other band, the vegetarians Miss J. U. B., Group V, and Miss L. B., Group VII, had a metabolism very considerably less than any one of the controls in the same group.
TEE JOUBNAL OF *IoLooIc*L CHEMISTRY, TO‘. xx, NO. 3
Miss R. A.. . . . . . . . . Miss G. F.. . . . . . . . .
GROUP VII Vegetarian
Miss L. B. . . Non-vegetarian
Miss I. B . . . . Miss E. T.. .
GROUP VIII Vegetarian
Mrs. A. L. . Miss M. J. . .
Non-vegetarian Miss H. T.. . Miss J.. . . . . .
GROUP IX Vegetarian
Miss J. T.. . . Non-vegetarian
Miss 9. C.. .
. . . . . . 47.0 167 ~ 1168 24.9
50.1 ‘...“..,
. . . . . . . . 46.7
. . 42.6 165
44.9 159 1272 28.3 815 44.8 157 1189 26.5 767
45.0 159 1393 30.9 896 43.0 159 1158 26.9 766
40.0 168 1269 ~ 31.7
1168 ! 27.4
881
779
lues for
i
a’
cm.
Total
151 i 1178
155 1293 155 1233
166 1235 24.7 164 1336 28.6
Per kgm.
cd.
24.0
25.5 25.4
As noted with men, a comparison of the average v
‘er square meter
__-- cd.
712
765 754
730
737 838
women, irrespective of weight and height, may not properly be made; nevertheless the values for the separate groups may be averaged and thus a grand average obtained which gives a reason- ably correct picture of the probable relationship between the vegetarian and non-vegetarian women. These averages, which are calculated on the basis of per kgm. of body weight and per square meter of body surface, are given in Table IV. The vegetarians show a higher metabolism than the controls in four of the nine groups. In the grand average the heat production of the vegetarians on the bases of per kgm. of body weight and per square meter of body surface is but slightly less than the
heat production of the non-vegetarians, the difference between the two classes being a little less than 2 per cent.
From these data we may conclude that the male vegetarians have a slightly less metabolism per kgm. of body weight and per square meter of body surface than have the individuals living on a mixed diet with whom they are compared. This difference is so small, however, that as a general picture no essentially striking difference is apparent between male vegetarians and non- vegetarians. Certainly there is nothing to warrant the belief
TABLE IV.
Summary of comparison of vegetarians and non-vegetarians. (Experiments with women.) ~--__ I I HE.m PBODUCTION PEB 24 EBB.
(COBmuT~D)
GROUP NO. I i Per km. of body weight ! I VegetluiaDa
that the male vegetarian subsists upon a materially lower met- abolic plane. With the female vegetarians, the slight difference in metabolism shown by the male vegetarians entirely disappears. We may, therefore, fairly conclude that living upon a vegetarian diet for a longer or shorter period does not fundamentally alter the basal gaseous metabolism.
One of the particular reasons for instituting a study of the me- tabolism of vegetarians is to note if the body of the vegetarians contains a larger proportion of readily combustible carbohydrate
(glycogen) as the result of their special diet. Obviously vegetari- ans, in order to secure the total energy required for t.he day, must secure a larger proportion of energy from carbohydrate than do individuals living on a mixed diet; for it is much easier to obtain a larger proportion of animal fat than of vegetable fat. It was thought possible that vegetarians, subsisting for a long time on a diet rich in carbohydrates, would have acquired a stor- age of glycogen above that of an individual living on a mixed diet, and that consequently in a quiet, resting condition, twelve hours after the last meal, they would show a katabolism with a larger proportion of carbohydrate. This would obviously be indicated by the respiratory quotient.
In any comparison of the respiratory quotients it should be taken into consideration that this factor is extremely difficult to determine with great accuracy, since all the errors incidental to the determination of both the carbon dioxide production and the oxygen consumption affect the values for the respiratory quotient. One must, therefore, speak somewhat guardedly in comparing respiratory quotients. On the other hand, we have available respiratory quotients obtained upon twenty-two veget.arians (and here it is unnecessary, for the present at least, to make distinctions between male and female vegetarians and between individuals of different height, weight, and age). We may properly compare these, values with respiratory quotients previously determined upon 132 individuals subsisting on a mixed diet. In such a comparison deductions may reasonably be drawn from an average quotient. The average respiratory quotient found with the 22 vegetarians (i.e., 11 men and 11 women), was 0.83, while the average quotient found with 132 individuals subsisting on a mixed diet (77 men and 55 women) was 0.81. This difference is slight and is wholly incompatible with the belief that vegetarians, when in the post-absorptive condition, have available any considerably larger proportion of easily com- bustible carbohydrate material than have non-vegetarians.
