Influence of Mineral Oil on Assimilation of Vitamin A from Spinach

Abstract

The inhibitory effect of mineral oil on the absorption and utilization of vitamin A has been discussed by several workers. 1 , 2 , 3 Rowntree 1 considers the phenomenon of little significance so long as abundance of vitamin is provided. Jackson 2 finds but slight effect upon vitamin absorption if the mineral oil is fed separately from the butter fat. In none of the investigations has special attention been given to the effect of mineral oil upon vitamin A from a vegetable source, nor to the quantity of vitamin actually diverted by the parallel use of mineral oil.

Would mineral oil effect the carotin of plant cells in the same manner that it did the true vitamin A from an animal source? This question arose at the time some vitamin A assay work on a dry spinach product was being completed in the laboratory. At the end of the 8 weeks'test period these rats were given 1/2 cc. of mineral oil daily in addition to their spinach supplement. The results were striking and left no doubt that mineral oil does seriously interfere with the assimilation of the provitamin in plant cells.

The subject seemed to warrant further consideration from a quantitative standpoint. Fresh green spinach was used in all subsequent experiments and the standard vitamin A technique discussed by Sherman 4 was employed. Repeated control experiments had demonstrated that 10 mg. of spinach contained slightly more than one unit of vitamin A. When quantities of mineral oil ranging from 1/4 to 1 cc. were fed with 10 mg. of spinach, the rats failed to gain and died in from 3 to 11 weeks. This was to be expected as all workers have emphasized that the effect of mineral oil is most pronounced when minimum or marginal doses of the vitamin supplement are employed.

The present question may then be stated: How much more spinach would it be necessary to feed in the presence of 1/2 cc. of mineral oil in order to obtain the same limited growth as that obtained with 10 mg. of spinach alone?

Graded amounts of spinach were fed, keeping the mineral oil dosage constant (1/2 cc. daily). This amount has been used by several investigators and is comparable to a moderate human dose. The grade of oil used was that known as Standard Oil “Stano-Hnd” heavy (Viscosity 310 sec. at 100° F. and pour test 0°F.).