Children can also take calcium as it contains both vitamin D and calcium, and being able to supplement vitamin D with calcium helps both calcium and vitamin D. The effect is twofold. Because simply supplementing vitamin D without calcium or simply supplementing calcium without vitamin D is not conducive to calcium supplementation. It is important to observe and check the stool and dynamically test the blood levels of calcium and vitamin D when giving calcium to children, and make dynamic adjustments according to the levels of vitamin D and calcium in the blood to avoid hypercalcemia or an overdose of vitamin D after applying too much calcium.