Signs and symptoms of vitamin D deficiency include bone pain, muscle weakness, rickets, various cancers and asthma, according to MedcineNet. Preliminary studies show other signs of vitamin D deficiency may be related to cardiovascular disease and autoimmune diseases.
People who are deficient in vitamin D are between 8 and 14 percent more likely to suffer from depression, notes MedicineNet. Vitamin D helps prevent the depletion of levels of serotonin and dopamine, two brain chemicals that are involved in regulating mood. In studies of depressed people, scientists found that the people with the lowest vitamin D levels were most likely to commit suicide.
Rickets, or osteomalacia in adults, leads to deformities in bones due to poor absorption of calcium and phosphate because of severely low vitamin D levels, notes MedicineNet. A lack of this vitamin creates soft bones and poor mineralization. Contrarily, mild vitamin D deficiency does not show any symptoms at all.
The Institute of Medicine found studies that linked a lack of vitamin D to multiple sclerosis, heart disease, respiratory health, obesity and muscle function, says MedicineNet. Other maladies that may be exacerbated by vitamin D deficiencies include cancer and erythropoiesis. Levels of vitamin D may affect a woman's pregnancy and speed the aging process in adults. In addition to bones and the immune system, vitamin D helps regulate the kidneys, small intestine, pancreas and parathyroid gland, notes Merck Manual.
The recommended daily allowance of vitamin D for adults is 600 international units, according to Mayo Clinic. Adults older than 70 should get 800 IU per day. Exposure to sunlight represents one way people get enough vitamin D, otherwise children and adults should consume foods such milk and yogurt that are fortified with the nutrient. Salmon, tuna, halibut and trout have vitamin D in them.