one of the fat-soluble vitamins, vitamin D constitutes two major forms which are vitamin D2 or ergocalciferol and vitamin D3 or cholecalciferol. Vitamin D2 is synthesized by plants whilst vitamin D3 is synthesized by the body. Vitamin D is naturally present in a number of food sources and dietary supplements and is also manufactured with the aid of sun exposure. It is produced within the body when ultraviolet-B or UVB rays from sunlight reaches the skin. The liver and the kidney eventually help to convert vitamin D to an active hormone form.
Functions of Vitamin D
Vitamin D plays several key roles in the maintenance of organ systems. For example:
* Vitamin D helps regulate calcium concentrations in the blood. Since it works more like a hormone, its active form, calcitriol acts with the parathyroid hormone or PTH. If the calcium level is low, this would trigger the secretion of PTH, which would stimulate the conversion of vitamin D to calcitriol. Calcitriol would then act to increase calcium absorption in the intestines, calcium resorption in the kidneys, and stimulate calcium release from the bones.
* Vitamin D helps maintain blood phosphorus levels. Low levels of vitamin D can result to an overactive parathyroid gland. Also with inadequate phosphorus in the body, bones cannot undergo normal mineralization.
* It is also said that vitamin D benefits the immune system since the T-cells or immune cells have receptors for vitamin D. It acts by boosting phagocytosis, the bodily functions to combat tumors, modulate neuromuscular and immune functions and reduce inflammation.
* Vitamin D is also responsible for maintaining normal cell growth and function. It may be an important element to the prevention and treatment of cancer. It has also been suggested that vitamin D plays a role in regulating the growth and function of brain cells.
* Research studies suggest that vitamin D, because of its anti-inflammatory effect, plays a role in providing protection against osteoporosis, hypertension, cancer, type 1 diabetes, psoriasis, and numerous autoimmune diseases.
Deficiency Conditions
There may be certain underlying causes of vitamin D deficiency. It can result from:
* Inadequate vitamin D intake together with inadequate sun exposure
* Certain disorders that compromise vitamin D absorption
* Conditions that can impair the conversion of vitamin D metabolites such as kidney or liver diseases or hereditary disorders.
Insufficient vitamin D intake can have serious effects on the bones, which can make them thin, brittle, or deformed. Vitamin D deficiency often results in conditions like:
* Rickets which is common in children and is characterized by delayed growth and deformity of long bones.
* Osteomalacia, which occurs in adults and results in thinning of the bones. Signs of proximal weakness and bone fragility are familiar characteristics.
* Osteoporosis which is a condition wherein the bone mineral density is reduced and bone fragility is increased.
Lack of vitamin D may also be linked to increased susceptibility of several chronic diseases like high blood pressure, cancer, tuberculosis, periodontal disease, multiple sclerosis, chronic pain, schizophrenia, depression, affective disorders, peripheral arterial disease, and a number of autoimmune diseases such as type-1 diabetes.
Deficiency Symptoms in Adults and Infants
Signs of vitamin D deficiency include muscle aches, myopathy or muscle weakness, and bone pain. These symptoms can occur at any age. Pregnant mothers who have vitamin D deficiency can also cause fetal deficiency.
