In 2010, the Institute of Medicine at the National Academy of Sciences increased the recommended daily intakes of vitamin D. Your body can synthesize this important vitamin when the skin is exposed to the sun, but many Americans are vitamin D deficient. The liver converts the vitamin D you get from the sun, your food or supplements into 25-hydroxyvitamin D, and its concentration in your blood is the most accurate indicator of vitamin D status. Low levels of vitamin D, which result in symptoms affecting your bones and muscles, may also be linked to various chronic diseases.
Muscle and Bone Pain
Vitamin D deficiency can result in osteomalacia, a mineralization defect in the skeleton that leads to decreased bone mineral density. Osteomalacia is associated with aches and pains in bones and muscles. You may have osteomalacia if you experience bone pain when you press your thumb on your breastbone or shin with moderate force. In "Mayo Clinic Proceedings," researchers noted in 2003 that individuals admitted to a hospital emergency department with muscle aches and bone pain who had a wide variety of diagnoses, including fibromyalgia, chronic fatigue syndrome and depression, were very likely to be deficient in vitamin D.
Skeletal muscles require vitamin D to function properly, and a deficiency in the vitamin can lead to muscle weakness. Children with muscle weakness resulting from low vitamin D may experience difficulty standing and delayed walking. In the elderly, muscle weakness leads to more frequent falling, which increases risk of hip fractures. A 2006 review in the "American Journal of Clinical Nutrition" revealed that increased intake of vitamin D significantly reduced the risk of falls.
Osteopenia and Osteoporosis
Adequate vitamin D is required for your body to absorb calcium from your intestines. When calcium intake or absorption is inadequate, your body mobilizes calcium stored in the bones to keep calcium levels in your blood within the normal range. Inadequate amounts can result in bone weakness and lead to osteopenia and osteoporosis. When you have osteopenia, your bone mineral density is low. In osteoporosis, bone mineral density is so low that your bones become weak and brittle and may fracture very easily.
Rickets is a preventable condition that affects infants, children and adolescents as a result of extreme, prolonged vitamin D deficiency. Individuals with rickets experience slow growth, softening and weakening of the bones, bone pain and muscle weakness. Vitamin D deficiency in childhood interrupts the mineralization of bones and softens the growth plates at the ends of bones. This condition can cause skeletal deformities, including bowed legs, thickened wrists and ankles and a protruding breastbone.
Emerging research has linked low vitamin D with various chronic diseases, including high blood pressure, certain types of cancers, increased risk of cardiovascular disease and increased risk of fatal cardiovascular events, autoimmune disease, dementia, depression, diabetes and glucose intolerance. In its 2010 Dietary Reference Intakes for Calcium and Vitamin D, the Institute of Medicine states that research linking low vitamin D to these conditions is inconclusive and additional research is needed to determine the role of low vitamin D in these conditions.