Bahareh Sedighy - Department of midwifery, Nursing & Midwifery sciences Development Research Center, Najafabad Branch, Islamic Azad University, Najafabad, Iran.
Nasim Khademi - Department of midwifery, Nursing & Midwifery sciences Development Research Center, Najafabad Branch, Islamic Azad University, Najafabad, Iran

Vitamin D has ۷ types from one to seven, of which D۲ and D۳ are most needed by the human body. Vitamin D is unique because it can be absorbed by the body both through food and sunlight. Sunlight is the most important source of this vitamin, which after irradiating the skin and absorption, part of it is converted into vitamin D and transferred to the kidney and liver to become the active vitamin needed by the body. Vitamin D۳ or Cholecalciferol, as a quality source of vitamin D, is very important for the health of the body. This type of vitamin, unlike type D۲, which is mostly found in plants, is mostly seen in animals, and this causes problems for vegetarians. Vitamin D۳ is produced from dihydrocholesterol in the skin and exposed to the sun's ultraviolet rays. Light-skinned people get their vitamin D from sunlight in less time than dark-skinned people. Approximately, by being in a place with sunny weather, all the vitamin D۳ a person needs is provided. Vitamin D is one of the fat-soluble vitamins, which by controlling the balance of calcium and phosphorus, increasing the absorption of phosphorus and calcium from the intestines and reducing excretion from the kidneys, causes the growth and strength of bones. Getting vitamin D and calcium increases muscle strength and coordination in the elderly. Vitamin D also prevents the occurrence of diseases such as rickets in children, osteomalacia in adults and osteoporosis in old age .This vitamin plays an important role in the process of cell growth and important metabolic processes of the body. Also, taking vitamin D is effective in brain health and preventing Alzheimer's disease.