Calcinogenic activity of vitamin D3 and vitamin D3 palmitate in rat and rabbit

Experimental hypervitaminosis D was produced in rabbits by feeding 25,000 I.U. vitamin D3 or the corresponding amount of vitamin D3 palmitate per kg of diet. Hypercalcemia and hyperphosphatemia was accompanied by increased CaBP activity and reduced weight gain in the vitamin D3 group as well as in the vitamin D3 ester group. The degree of calcification in the aorta and in the kidney also was similar in both groups. Increasing the vitamin intake by giving 10,000 I.U. vitamin D3 or vitamin D3 palmitate per day resulted in earlier and more widespread calcific deposits. In rats, receiving 50,000 I.U. vitamins D3 or vitamin D3 palmitate per kg of diet, calcification in soft tissue was much less extensive than in rabbits. But again, no difference was seen between vitamin D3 and vitamin D3 palmitate. These results indicate, that vitamin D3 esters are not suitable as a less calcinogenic form of vitamin D3.