Effect of a Diet Consisting Exclusively of Carrots on Serum Protein Concentration of the Rat. ∗

Abstract

It was pointed out 1 that no significant fall of serum protein concentration occurred in rats kept for a period of 5 months on a diet extremely low in protein, provided the diet was otherwise adequate. These results are at variance with the conclusions of Kohman, 2 and of Frisch, Mendel and Peters. 3 However, the diet used by these observers consisted in large part of carrots and the question therefore came up whether carrots alone may exercise some specific blood protein lowering effect. The present experiments were planned to obtain information about this possibility.

Eighty-eight young adult white rats were placed on a diet consisting exclusively of fresh carrots. No salts or vitamins were added. After varying intervals groups of 5 or 6 animals were exsanguinated under ether anesthesia, aliquot portions of serum were pooled and the total serum proteins were measured. 4 The experiment lasted 145 days during which time the rats remained well and active and there were none of the usual signs of vitamin deficiency. There was progressive weight loss.

In the majority of the animals there was a definite fall in serum protein concentration and values as low as 4.28, 4.44, 4.72 were obtained with some of the groups (control level 6.30–6.50 gm. %). Five rats among the whole group of 88 developed gross watery effusions into the serous cavities and in one of these animals the serum protein concentration was only 2.99 gm. %. It is of interest that the serum protein level bore no close relation to the duration of carrot feeding. Serum protein from a group of rats on the 61st day averaged 4.44 gm. %, from another group on the 82d day 5.06 gm. % and from the final group on the 145th day 4.28 gm. %.

The mechanism of the lowering of serum protein concentration after carrot feeding appears to be extremely complex. Neither lack of protein alone nor lack of vitamins seem to offer a complete explanation.