Vitamin D is fat-soluble vitamin, naturally present in some foods. It has several roles in the body. It promotes calcium and phosphorus absorption in the gut and maintains their normal blood level. Vitamin D also inhibits the release of parathyroid hormone which is responsible for bone resorption. It is believed that vitamin D improves muscles and immune system and prevents osteoporosis, cancer, high blood pressure and several autoimmune diseases.
Vitamin D can be obtained from exposure to sunlight which contributes production of the vitamin under the skin. For proper amount of vitamin D required length of sunbathing depends on person’s age, color of the skin and present medical condition. Older people produce less vitamin D due to their thinner skin. People with pigmented skin have to spend more time exposed to sun particularly in winter.
Vitamin D can be found, in small amount, in food. Types of food rich in vitamin D are oily fish (herring, tuna, salmon, etc.), mushrooms, egg yolk, liver, cheese, milk, and butter. Vitamin D is added to margarine, cereals and instant milk. In US, commercially fortified cow’s milk contains around 100 units of vitamin D per 8 ounces, which makes it the richest source of vitamin D.
Vitamin D DeficiencyVitamin D deficiency can occur due to several reasons: Insufficient vitamin D intake combined with insufficient exposure to sun. Failure to absorb vitamin D from the gut. Inability to synthesize vitamin D because of kidney or liver conditions.Infants are at risk of vitamin D deficiency because breast milk as well as infant milk formulas don’t contain enough vitamin D. Elderly people usually don’t eat foods rich in vitamin D and their vitamin D absorption can be restricted.
Inadequate sun exposure can be seen in infants and children since their parents often protect them from harmful effect of the sun. Also, people with darker skin and those living in northern parts of the world often experience vitamin D deficiency because of this reason.
Some diseases like celiac disease, Crohn’s disease and cystic fibrosis, impair body’s ability to absorb enough vitamin D. This function of the body can also be affected by surgery that removes part of the stomach or intestines, such as gastric bypass.
Kidneys and liver contain enzymes that transform vitamin D from the sun and food to biologically active vitamin D. Those who are suffering from kidney or liver disease may also suffer from vitamin D deficiency due to lack of mentioned enzymes. This also applies to familial diseases that damage liver or kidney enzymes responsible for production of biologically active vitamin D.
ComplicationsDeficiency in vitamin D can result in number of conditions and disorders. Symptoms of depression may increase because of lack of vitamin D. People with multiple sclerosis may experience complications from the same reason. They need to take additional vitamin D to prevent relapses. Sufficient vitamin D intake may aid in preventing multiple sclerosis as well. Vitamin D enhances immune system. Thereby, people with vitamin D deficiency become prone to infections and illnesses.