Sept. 1 , 1924 
Vitamin A Content of Fresh Eggs 
257 
these results it would appear that the 
minimum quantity of vitamin A re¬ 
quired for the normal growth of rats is 
furnished by an amount of fresh whole 
egg very little more than 0.5 gm. 
Since 0.5 gm. of egg was found ample 
to cure xerophthalmia, smaller amounts 
were tried, to determine the minimum 
dosage that could be used. Accord¬ 
ingly, six rats were fed 0.25 gm. of egg. 
The results in this case were decidedly 
poorer than those with the 0.5 gm. dose 
(fig. 3). Growth was slightly less, and 
the length of time required to cure the 
sore eyes was very much increased. 
One rat, No. 1808 while showing fair 
growth, still exhibited distinct signs of 
sore eyes at the close of the experiment, 
38 days after the beginning of the egg 
feeding. 
The lower limit seemed to have been 
reached at 0.25 gm., but another series 
was tested with 0.1 gm. of egg (fig. 
4). Although the growth recovery of 
these was not far different from that of 
those receiving 0.25 gm., the effective¬ 
ness of 0.1 gm. for curing xerophthalmia 
was found to be very slight. Only one 
rat, No. 1856, was completely cured 
after three weeks of feeding; and the 
others, even after six weeks, gave no 
indication that they would ever recover 
fully on this dosage. 
The fact that the weight increase of 
the rats receiving 0.1 gm. of egg was 
nearly identical with that of those 
receiving 0.25 gm., and not far below 
that of those receiving even 0.5 gm., 
is a somewhat surprising phenomenon 
which is being studied by the authors. 
DISCUSSION 
These experiments indicate that 
test rats, after having declined in 
weight and having developed xeroph¬ 
thalmia as a result of vitamin A 
deficiency, can be restored to normal 
weight by feeding 0.5 to 0.75 gm. of 
whole egg daily; and that 0.5 gm. is 
very near the quantity required to 
enable healthy young rats to maintain 
growth at a normal rate. If weight 
increase be not considered, but only the 
effectiveness for curing xerophthalmia, 
the lower limit is reached at about 0.25 
gm. Only one rat failed of complete 
cure on this dosage, and this one might 
possibly have recovered eventually. 
It is of interest to calculate these 
figures in terms which are sometimes 
used by other workers. Since the 
yolks compose about 35 per cent of the 
whole egg, 0.75 gm., 0.50 gm. and 0.25 
gm. of whole egg would then be equiva¬ 
lent to 0.26 gm., 0.17 gm., and 0.088 gm. 
respectively, of yolk. The minimum 
99182—25f—4 
quantity (0.25 gm. of yolk) which Hess 
found sufficient to protect rats from 
rickets was, therefore, very close to the 
minimal growth-restoring dose. Of 
the whole yolk 49.8 per cent is water. 
The quantity of egg yolk required, 
calculated to a dry basis, would there¬ 
fore be between 0.083 gm. and 0.13 
gm. for growth restoration, and 0.041 
gm. for the cure of xerophthalmia. 
On the assumption that all of the 
vitamin A is contained in the oil of the 
yolks, then, since 60 per cent of the 
dried yolk is oil, a little more than 0.05 
gm. of egg oil would be required for 
growth promotion, and 0.025 gm. 
would be required for the curing of 
xerophthalmia. Cod-liver oil has been 
found effective in doses of about 
0.001 gm. Therefore egg oil would 
have a vitamin A potency between 2 
and 4 per cent of that of the most 
potent cod-liver oil. 
SUMMARY 
Feeding experiments have shown 
that from 0.50 gm. to 0.75 gm. of fresh, 
whole egg fed daily supplies young rats 
with sufficient vitamin A for growth at 
a normal rate. A smaller quantity, 
0.25 gm, was found to be adequate to 
cure well advanced cases of xeroph¬ 
thalmia. 
LITERATURE CITED 
(1) Bloch, C. E. 
1924. BLINDNESS AND OTHER DISEASES IN 
CHILDREN ARISING FROM DEFICIENT 
NUTRITION (LACK OF FAT-SOLUBLE A FAC¬ 
TOR.) Amer. Jour. Diseases of Children 
27: 139-148. 
(2) Casparis, H., Shipley, P. G., and Kramer, 
B. 1923. THE ANTIRACHITIC INFLUENCE OF 
egg yolk. Jour. Amer. Med. Assoc. 
81: 818-819. 
(3) Cramer, W. 
1924. AN ADDRESS ON VITAMINS AND THE 
BORDERLAND BETWEEN HEALTH AND 
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(4) Hess, H. F. 
1923. THE THERAPEUTIC VALUE OF EGG YOLK 
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81: 15-17, illus. 
(5) -, WEINSTOCK, M., AND TOLSTOI, E. 
1923. THE INFLUENCE OF NUTRITION DURING 
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DEVELOPMENT OF RICKETS IN RATS. PrOC. 
Soc. Exp. Biol. & Med. 20: 371-372. 
(6) McCollum, E. V., and Davis, M. 
1914. FURTHER OBSERVATIONS ON THE 
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(7) Osborne, T. B., and Mendel, L. B. 
1914. THE INFLUENCE OF COD-LIVER OIL AND 
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( 8 ) - 
1919. THE NUTRITIVE VALUE OF THE WHEAT 
KERNEL AND ITS MILLING PRODUCTS. 
Jour. Biol. Chem. 37: 557-601, illus. 
(9) Palmer, L. S., and Kennedy, C. 
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