Читать книгу The Vitamin Cure - Monte Lai - Страница 21

 • Calcium homeostasis. Concentrations of calcium are closely regulated in the body, and calcium homeostasis is related to normal physiological functions in the nervous system, bones, muscles, and many other organs. To maintain good health, it is of foremost importance to carefully control calcium concentration in the body. Vitamin D enhances the deposition of calcium in the bones, while parathyroid hormones release calcium from the bones. The interplay between vitamin D and parathyroid hormones controls calcium concentration in the body.

 • Phosphorus homeostasis. Similarly, concentrations of phosphorus ions influence many normal physiological functions in muscles, bones, and other organs in the body. When phosphorus levels are low in the blood, vitamin D instructs the intestines to increase absorption of phosphorus ions, and when the phosphorus ion levels are too high, parathyroid hormones instruct the kidneys to excrete excessive phosphorus ions in the urine.

 • Cell proliferation and differentiation. Proliferation is a self-replication process by which a cell multiplies and produces more cells, and differentiation is like assigning a given cell specific tasks to perform. When proliferation is dominant, differentiation will be slow, and vice versa. Uncontrollable proliferation can lead to cancer. Vitamin D promotes cell differentiation and prevents cell proliferation to curtail the risk of tumor formation.

 • Immune system. Many immune cells—including monocytes, macrophages, and T cells—have their own vitamin D activation processes through which the active form of vitamin D influences the gene expression of immune cells. Vitamin D enhances innate immunity (general immune defense) and inhibits autoimmunity (misdirected immune responses). Vitamin D deficiency increases susceptibility to autoimmune disorders.

 • Insulin secretion. The active form of vitamin D enters pancreatic cells, regulates gene expression in pancreatic cells, and stimulates secretion of insulin from pancreatic cells.