Vitamin D not only helps in the absorption of calcium, but also plays a vital role in the absorption of calcium. If vitamin D deficiency means hypocalcemia and rickets, it can lead to rickets in infants and children, especially vitamin D-dependent rickets. As adults, even a lack of vitamin D can lead to the formation of osteoporosis, which seriously affects calcium absorption and leads to significant osteoporosis and even a series of pathological fractures and other diseases.