Vitamin D is an essential nutrient that plays an important role in maintaining overall health, including the proper functioning of the kidneys. Although vitamin D is best known for its contribution to bone health and calcium regulation, increasing evidence suggests that it also has important effects on kidney function and may contribute to protecting the kidneys from disease. The kidneys play a central role in vitamin D metabolism. They convert the inactive form of vitamin D into its biologically active form, known as calcitriol. This active hormone helps regulate calcium and phosphorus levels in the body, which are essential for healthy bones, muscles, and normal cellular functions. When kidney function declines, the kidneys may become less able to produce active vitamin D, potentially leading to disturbances in mineral balance and bone health. Vitamin D also appears to have effects beyond mineral metabolism. It may help regulate inflammation, immune responses, and blood pressure, all of which can influence kidney health. Some studies have found an association between low vitamin D levels and chronic kidney disease. However, low vitamin D may be a consequence of kidney disease rather than its direct cause, and more research is needed to fully understand this relationship. Maintaining adequate vitamin D levels can therefore be an important part of general kidney and bone health. Vitamin D can be obtained through safe exposure to sunlight and foods such as fatty fish, egg yolks, and fortified products. Supplements may be recommended for people with documented deficiency, but they should be taken under medical guidance, particularly in individuals with kidney disease. In conclusion, vitamin D has an important relationship with kidney function and mineral balance. Maintaining appropriate levels may support overall health, while excessive supplementation should be avoided because it can cause high calcium levels and potentially harm the kidneys. Al-Mustaqbal University The First University in Iraq