The Anti-Rachitic Value of Winter Spinach

Abstract

Direct metabolic experiments were carried out on young rats in order to compare the influence upon the retention of Ca and P of adding cod liver oil or fresh green winter spinach leaves daily to diets deficient in all fat-soluble vitamins. The method previously described by Boas was employed, with the additional refinement that feces, urine and uneaten food were collected and analyzed separately. For this purpose separators designed by Gross and Connell were used. The addition of cod-liver oil to the diet resulted in an improvement in the general health and an increase in the rate of growth of both skeleton and entire body. The degree of calcification of the skeleton was also improved, for there was a rise in the amount of Ca retained per unit increase in body weight. The fresh leaves of winter-grown spinach added to the experimental diet caused an even greater improvement in the well-being of the rats and in the rate of growth, but the weight of the skeleton was not proportionally increased. Winter spinach, therefore, contains an amount of vitamin D which is negligible compared with its content of vitamin A. Of the total Ca excretion of the rats, 95-98% was found in the feces; this partition was inde- pendent of the amount of fat-soluble vitamins in the diet. Both cod-liver oil and spinach, when added to a diet deficient in fat-soluble vitamins, caused an increase in the amount of P excreted in the urine at the expense of that excreted in the feces.