Sun exposure does not directly replenish calcium, but you can get vitamin D from sun exposure, and vitamin D helps with calcium absorption. Many foods such as milk, kelp, shrimp, soy products, etc., are important sources of calcium, sun exposure can not directly supplement calcium. Human skin contains 7-dehydrocholesterol, which can be transformed into vitamin D under the action of ultraviolet light, and vitamin D has the effect of promoting the active absorption of calcium. Therefore, sun exposure helps calcium absorption. Vitamin D deficiency, infants and young children are prone to rickets, adults are prone to osteoporosis, osteomalacia and so on. Vitamin D-rich food is less, clinical vitamin D deficiency is very much, especially the elderly, children and perimenopausal women, it is recommended to sunbathe for one hour a day, spring and fall in the morning and afternoon can be, the winter choice of noon, summer before 9:00 a.m. and after 5:00 p.m., and in the sun at the same time to do some exercise is more effective. It is recommended to moderate sun exposure or additional vitamin D supplementation under the guidance of a physician, but note that, do not be exposed to strong summer sunlight, so as not to burn the skin.