Vitamin D deficiency is linked with increased risks of osteoarthritis, cancer, cardiovascular disease and depression. Low levels of vitamin D are also associated with autoimmune disorders, multiple sclerosis and Type 1 diabetes, as reported by Healthline.
Symptoms of vitamin D deficiency can include bone pain and muscle weakness, and it is traditionally associated with the bone disease rickets, as stated by WebMD. Even in patients who exhibit no obvious symptoms, low levels of vitamin D in the blood are associated with an elevated risk of death from cardiovascular disease, asthma in children and cognitive impairment in seniors.
Vitamin D helps the body utilize calcium, and it is necessary for strong, healthy bones, according to WebMD. The human body does not produce vitamin D, explains Healthline. Sunlight is the primary source of vitamin D, and food sources include fatty fish, cheese, egg yolks, beef liver and fortified cereals. People with dark skin are at risk for vitamin D deficiency, as melanin negatively affects the body's ability to make vitamin D from sunlight. Additionally, studies show that people who are obese often have low blood levels of vitamin D. Those over 65 produce less vitamin D than younger adults and may require vitamin D supplements.