Further Studies on Dietary Factors Associated with Nutritional Muscle Dystrophy

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Abstract
Dietary studies on the prevention or cure of nutritional muscular dystrophy in rabbits demonstrate clearly the multiple factor nature of this deficiency disease. All the essential factors are present in acetone extracts of wheat germ or cottonseed, though not in adequate amounts in the latter. Fresh green leaves of lettuce fed in large amounts with the basal diet can cure dystrophic rabbits and maintain them in good health for a long time. Whole wheat germ was fractionated into its fat-soluble and water-soluble components. Neither fraction by itself can either prevent or cure dystrophy. The fat-soluble material, or the non-saponifiable portion of it, incorporated into the basal diet delays the onset of dystrophy while the water-soluble fraction, either as the extract or as the residue left over from the extraction with petroleum ether, does not even affect the rapidity with which dystrophy develops on diet 13. However, when the two extracts are fed together to severely dystrophic rabbits they recover very quickly and grow vigorously. Many animals after they made good progress on these curative diets for long periods of time have had a remission of the disease. Since in every case there has been some pulmonary complication, the recurrence of dystrophy after the animals have been gaining steadily and behaved entirely normally even for months will need further investigation. Cures have been effected not only by combining wheat germ oil and the water-soluble fraction of wheat germ but also by combining the latter fraction with a petroleum ether extract of wheat germ or with its non-saponifiable fraction, as well as by combining the fat-soluble fraction with yeast or with different vitamin B concentrates. It may, therefore, be regarded as proved that one of the essential dietary factors is present in the non-saponifiable fraction of the wheat germ oil. The fact that this factor is absent in linseed oil but is found also in lettuce, cottonseed or corn oil, showing that its distribution is similar to that of vitamin E, and the fact that it is destroyed by the same treatment which destroys vitamin E indicate that both are either very closely associated or possibly even identical. Pappenheimer and Goettsch ('31) and Morgulis and Spencer ('36) found that muscle dystrophy in rabbits cannot be cured by vitamin E concentrates alone but, on the other hand, foods which prevent or cure this condition contain vitamin E. We have shown that a petroleum ether extract of wheat germ or the non-saponifiable fraction of wheat germ oil as supplements to diet 13 merely delay the onset of dystrophy but do not prevent it or cure it. We tested these preparations for the vitamin E content by studying their effect in restoring fertility in rats which have cased to reproduce on a vitamin E-free diet, and found them to be effective sources of this vitamin. But they are effective in curing or preventing muscle dystrophy only when they are administered in combination with the water soluble fraction of wheat germ, or various concentrates of the vitamin B complex. Judging by the distribution of the water-soluble factor (or factors?) this obviously belongs in the vitamin B complex since yeast, wheat germ and lettuce are all good sources, and experiments now in progress further substantiate this assumption. The dystrophy-producing diet itself must contain enough of the recognized growth factors since Pappenheimer and Goettsch ('31) maintained rats for three generations and we reared two generations of rats on diet 13 or 313 without any ill effects. The antineuritic vitamin B1 is excluded automatically and B2 (riboflavin) can also be ruled out safely because Guha ('31) has shown that this factor is not destroyed by Perhydrol (Merck) while our diet 313, which is treated with Superoxol, is as effective in producing dystrophy as is diet 13 treated with FeCl3. Vitamin B6 may likewise be disregarded because it is not extracted by acetone, while our acetone extract of wheat germ is very effective in preventing or curing nutritional dystrophy. We must, therefore, consider vitamin B4 which Elvehjem ('35) found to be very labile, especially in the presence of oxygen. It is present in wheat, yeast and green foods (lettuce, alfalfa) just as the water-soluble dystrophy-preventive factor which we have been studying. The fact that Pappenheimer and Goettsch ('34) produced a purely myopathic condition in ducklings on the same synthetic diet which in chicks causes a myelopathic disease thought to be similar to a B4 deficiency further suggests a possible connection between this vitamin and our water-soluble factor. However, there is one very serious objection to identifying these two dietary factors which must not be overlooked, namely, that rats do well even for several generations on the diets which produce muscle dystrophy in rabbits. In conclusion it may be said that of the essential nutritional factors necessary for the integrity of the skeletal muscles the fat-soluble one is very closely associated or perhaps even identical with vitamin E and is present in the oil of wheat germ, cottonseed, corn, also in lettuce and alfalfa. It is also present in the non-saponifiable portion of the oil and in our ether, petroleum ether or acetone extracts of wheat germ. It can be separated from the acetone extract bymeans of hexane. The water-soluble fraction can be obtained by extraction of wheat germ with 70% alcohol or with acetone, and is also present in the wheat germ residue after extraction with petroleum ether. This fraction belongs to the vitamin B complex because it can be furnished by lettuce, yeast and a variety of vitamin B concentrates.