Lafayette B. Mendel

The Iodine Values of “Physiological” or “Synthetic” Rat Fat.

Male albino rats taken at weaning when 21 days of age were fasted for 2 days in order that a partial depletion of the stored fat might ensue, thereby lessening its influence on the later resulting “synthetic” fat. The rats were then fed a diet consisting of 18% casein (extracted with alcohol and ether), 77% sucrose, and 5% salt mixture (Osborne and Mendel), supplemented daily by the following: a hot water extract of pigs liver (0.4 gm. dried liver), 100 mgm. of yeast concentrate (Harris), 20 mgm. of a non-saponifiable fraction of cod liver oil (a pasty material, Oscodal†—Iodine Number 110), and 0.016 mgm. of irradiated ergosterol (dissolved in alcohol). Four other groups of rats (5 or more in a group) were fed this “fat free” diet modified so that the first group received an addition of 20 mgm. of peanut oil (Iodine Number 84); the second had the non-saponifiable fraction of cod liver oil substituted by 20 mgm. of cod liver oil (Iodine Number 160); the third received the same diet as the second group with the addition of 20 mgm. of peanut oil; and the last had the extracted casein replaced by commercial casein, the yeast concentrate substituted by yeast and the irradiated ergosterol omitted.†† From the analyses of the dietary components, it is calculated that the rats on the “fat free” diet received daily probably less than 7 mgm. of fatty materials, other than the non-saponifiable matter from cod liver oil.

DIET AND BODY FAT

Rats first fed soybean oil and peanut oil diets, then subjected to the process of fat depletion through selective starvation, involving 23 to 27 per cent. loss in body weight, before being fed a hardening diet, yielded harder fats-fats of lower iodine number values-than the fats of rats which were not starved before being fed the carbohydrate-rich diet. In other words, through the process of starvation, the soft oily fat produced on diets containing soybean or peanut oils is very largely removed, thereby permitting the deposit of a hard fat. To obtain a fat of equal hardness from rats which were not subjected to the starvation treatment would have required a much longer period of feeding of the diet rich in starch than was found necessary with rats after first being starved. The growth of recovery made by the rats of the starved lots was made on a low food intake. With the starved rats flrst fed peanut oil, the food intake of the carbohydrate-rich diet was less than with the non-starved group. The possible application of these findings to practical animal husbandry is obvious.

The distribution of vitamin-B in the wheat kernel

Foods containing various percentages of wheat and wheat derivatives, and comparable to each other in their content of all known dietary essentials except such quantities of vitamin-B as might be present in the wheat product used were fed to mice; and the rate of growth on these foods was observed. When the entire wheat kernel was thus used as the source of vitamin-B in the diet, admixtures of from fifteen per cent. (Marquis spring wheat), to forty per cent. (Minnesota winter wheat), were required to insure growth at a normal rate. The approximate concentration of vitamin-B in each of the milling products from a single lot of winter wheat was estimated. The “patent flour” contained no appreciable vitamin; the “first clear” and “second clear” displayed about the same concentration as the unmilled grain; the “low grade flour” and “bran” were about twice as rich; the “standard middlings” (which included the portion containing most of the embryo) were four times as rich as the entire grain. “Hand-dissected” portions of grains, representing more nearly the true structural divisions of both spring and winter wheat were also investigated. Vitamin-B was found in both embryo and endospern. The concentration in the embryo was several times as great as that in the endosperm; but owing to the small percentage of the entire kernel represented by the embryo, the absolute quantity of vitamin-B contained therein was not more than a sixth of the total amount in the grain. of the total amount in the grain. No difference could be detected between “hand-dissected “ and “commercial “ embryos. The presence or absence respectively of the embryo in the two ends of the grain, when fed separately, did not appreciably affect the concentration of vitamin-B in these two portions.

Diet and roughage in relation to the experimental scurvy of guinea pigs

It has been repeatedly demonstrated that exclusive diets of cereals produce scurvy in the guinea pig. We have fed filter paper, sawdust and hay respectively, as supplements to an oat diet without averting the appearance of scurvy. Duration of the disease and decline were not appreciably different when these supplements were fed. The addition of 7, 10, or 18 per cent. of paper pulp to a special soy bean diet 1 failed to supply an antiscorbutic property. Feeding raw milk in addition to oats induces marked constipation with impaction of feces in the cecum. Animals fed 40 c.c. milk daily showed definite symptoms of scurvy in about a month. As the daily allowance of milk was increased, the symptoms seemed to recede in severity. Yet even when 80 c.c. milk were consumed daily, the animals became very constipated and died; but there were scarcely any signs of scurvy. Autopsy of such a case revealed absence of the typical macroscopic hemorrhages or of fragility of the bones. These observations appear to confirm the findings of Chick, Hume and Skelton, 2 which indicate that a sufficient amount of milk fed to guinea pigs will prevent scurvy. Such observations render debatable the hypothesis that the experimental scurvy of guinea pigs is attributable to failure of normal intestinal movement. Preliminary experiments on the nutritive qualities of descicated vegetables indicate that the drying of fresh cabbage does not entirely remove its antiscorbutic property. 1

The influence of diet on the chemical composition of the body.

The investigation was an attempt to ascertain to what extent, if at all, the fundamental chemical structure of an organism can be altered by variations in diet or changed nutritive conditions. White mice were kept on dietaries of widely different character, e. g., high protein, protein and fat, low protein and carbohydrate, etc., during considerable periods of time, and then killed and analyzed. The data are being published elsewhere. They are interpreted to indicate that although the fat and water content of such organisms show variations through a very wride range, there is a constant interdependence, even in cases of malnutrition. High content of fat is accompanied by lower water content, and vice versa. When the water content of the body is calculated on the basis of the fat-free tissue, the range of variation is remarkably small (70 to 74 per cent. of water). In order to afford some direct basis for a comparison of the tissue substance aside from its water and fat and the inorganic skeletal structure, the nitrogen content of the entire animals was calculated on a water-, fat-and ash-free basis. With few exceptions the animals afforded figures within narrow range above or below 16 per cent. of nitrogen. The constancy of composition of the organism suggests that it is not possible ordinarily to upset the relative composition of the body by dietetic measures, aside from altering the fat and glycogen content. Normal growth proceeds only through assimilation of all the essential body constituents in the proportion in which they are normally found in the body; and in tissue disintegration the loss is likewise general, not restricted to individual components of the fundamental structure,