What the research says

Research on vitamin D use for certain conditions shows:

• Cancer. Findings on whether vitamin D can help prevent cancer are mixed. More studies are needed to find out whether vitamin D supplements may lower the risk of certain cancers or the risk of dying from cancer.
• Cognitive health. Research shows that people with low levels of vitamin D in the blood are less able to think and learn, called cognitive decline. But more studies are needed to find out whether vitamin D supplements may help.
• Bone conditions passed through families, called inherited conditions. Vitamin D supplements can be used to help treat inherited conditions that happen when the body can't take in or use vitamin D. One such condition is familial hypophosphatemia.
• Multiple sclerosis. Research suggests that long-term use of vitamin D supplements may lower the risk of multiple sclerosis. More study is needed.
• Osteomalacia. Vitamin D supplements treat adults with extreme vitamin D deficiency that results in this softening of the bones.
• Osteoporosis. Studies suggest that people who get enough vitamin D and calcium in their diets can slow bone mineral loss. This helps prevent the bone-thinning condition osteoporosis and lower the number of bone fractures osteoporosis causes.
• Psoriasis. Vitamin D treats plaque-type psoriasis in some people. Vitamin D or a cream that has a form of vitamin D called calcipotriene can be used on the skin.
• Rickets. Not having enough vitamin D in the body can cause this rare condition that weakens bones in children. Taking a vitamin D supplement can prevent and treat the condition.