Vitamin D


Vitamin D is found in many foods, including fish, eggs, fortified milk, and cod liver oil. The sun also adds to the body's daily production of vitamin D, and as little as 10 minutes of exposure is thought to prevent deficiency.
The term "vitamin D" refers to several different forms of this vitamin. Two forms are important in humans: vitamin D2, which is made by plants, and vitamin D3, which is made by human skin when exposed to sunlight. Foods may be fortified with vitamin D2 or D3.
The major role of vitamin D is to maintain normal blood levels of calcium and phosphorus. Vitamin D helps the body absorb calcium, which forms and maintains strong bones. It is used alone or together with calcium to improve bone health and decrease fractures. Vitamin D may also protect against osteoporosis, high blood pressure, cancer, and other diseases.
Rickets and osteomalacia are classic vitamin D deficiency diseases. In children, vitamin D deficiency causes rickets, which is a softening or weakening of the bones. In adults, vitamin D deficiency can lead to osteomalacia, which causes weak bones and muscles. People who may be at a high risk for vitamin D deficiency include those who are elderly or obese, those with limited sun exposure, and babies who are exclusively breastfed. People who have conditions such as cystic fibrosis (mucus build-up in the lungs) or inflammatory bowel disease are also at risk for vitamin D deficiency.

Related Terms

1,25-DHCC, 1,25-dihydroxy-22-ovavitamin D(3), 1,25-dihydroxycholecalciferol, 1,25-dihydroxy-vitamin-D (1,25(OH)(2)D), 1,25-dihydroxyvitamin D3, 1,25-diOHC, 1,25(OH) 2D3, 1-alpha (OH) D3, 19-nor-1, 1-alpha-hydroxycholecalciferol, 1-alpha-hydroxyvitamin D2, 1-hydroxyvitamin D, 22-oxacalcitriol (OCT), 24,25(OH)(2)vitamin D(3), 25 hydroxyvitamin D (25(OH)D), 25-dihydroxyvitamin D2, 25-dihydroxyvitamin D2, 19-nor-1, 25-HCC, 25-hydroxycholecalciferol, 25-hydroxyvitamin D, 25-hydroxyvitamin D3, 25-OHCC, 25-OHD3, activated 7-dehydrocholesterol, activated ergosterol, alfacalcidol, calcifediol, calcipotriene, calcipotriol, calcitriol, cholecalciferol, colecalciferol, cod liver oil, dichysterol, dihydrotachysterol, dihydrotachysterol 2, doxercalciferol, ecocalcidiol, ED-21 (vitamin D analog), ED-71 (vitamin D analog), ergocalciferol, ergocalciferolum, falecalcitrol, hexafluoro-1,25dihydroxyvitamin D3, irradiated ergosterol, maxacalcitol, MC903, Ostelin®, paracalcin, paricalcitol, tacalcitol, Vi-delta Liquid emulsion®, viosterol, vitamin D2, vitamin D3, vitamina D.

evidence table

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.
Deficiency (phosphate) (Grade: A)
Familial hypophosphatemia is a rare, inherited condition in which there are low blood levels of phosphate and problems with vitamin D metabolism. It is a form of rickets. Taking calcitriol or dihydrotachysterol by mouth along with phosphate supplements is effective for treating bone disorders in people with this disease. Those with this disorder should be monitored by a medical professional.
Kidney disease (causing low phosphate levels) (Grade: A)
Fanconi syndrome is a kidney disease in which nutrients, including phosphate, are lost in the urine instead of being reabsorbed by the body. Taking ergocalciferol by mouth is effective for treating low phosphate levels caused by Fanconi syndrome.
Osteomalacia (bone softening in adults) (Grade: A)
Adults who have severe vitamin D deficiency may experience bone pain and softness, as well as muscle weakness. Osteomalacia may be found among the following people: those who are elderly and have diets low in vitamin D; those with problems absorbing vitamin D; those without enough sun exposure; those who undergo stomach or intestine surgery; those with bone disease caused by aluminum; those with chronic liver disease; or those with bone disease associated with kidney problems. Treatment for osteomalacia depends on the cause of the disease and often includes pain control and surgery, as well as vitamin D and phosphate-binding agents.
Psoriasis (disorder causing skin redness and irritation) (Grade: A)
Many different approaches are used to treat psoriasis, including light therapy, stress reduction, moisturizers, or salicylic acid. For more severe cases, calcipotriene (Dovonex®), a man-made substance similar to vitamin D3, may help control skin cell growth. This agent is a first-line treatment for mild-to-moderate psoriasis. Calcipotriene is also available with betamethasone and may be safe for up to one year. Vitamin D3 (tacalcitol) ointment or high doses of becocalcidiol applied to the skin are also thought to be safe and well-tolerated.
Rickets (bone weakening in children) (Grade: A)
Rickets may develop in children who have vitamin D deficiency caused by a diet low in vitamin D, a lack of sunlight, or both. Babies fed only breast milk (without supplemental vitamin D) may also develop rickets. Ergocalciferol or cholecalciferol is effective for treating rickets caused by vitamin D deficiency. Calcitriol should be used in those with kidney failure. Treatment should be under medical supervision.
Thyroid conditions (causing low calcium levels) (Grade: A)
Low levels of parathyroid hormone may occur after surgery to remove the parathyroid glands. Taking high doses of dihydrotachysterol, calcitriol, or ergocalciferol by mouth, with or without calcium, may help increase calcium levels in people with this type of thyroid problem. Increasing calcium intake, with or without vitamin D, may reduce the risk of underactive parathyroid glands.
Thyroid conditions (due to low vitamin D levels) (Grade: A)
Some people may have overactive parathyroid glands due to low levels of vitamin D, and vitamin D is the first treatment for this disorder. For people who have overactive parathyroid glands due to other causes, surgery to remove the glands is often recommended. Studies suggest that vitamin D may help reduce the risk of further thyroid problems after undergoing partial or total removal of the parathyroid glands.
Vitamin D deficiency (Grade: A)
Vitamin D deficiency is associated with many conditions, including bone loss, kidney disease, lung disorders, diabetes, stomach and intestine problems, and heart disease. Vitamin D supplementation has been found to help prevent or treat vitamin D deficiency.
Dental cavities (Grade: B)
Much evidence has shown that vitamin D helps prevent cavities; however, more high-quality research is needed to further support this finding.
Fall prevention (Grade: B)
Many studies suggest that vitamin D helps prevent falls, especially in people who live in care facilities. However, there is conflicting evidence. Substances similar to vitamin D have been shown to help prevent falls and reduce fractures, including alfacalcidol and alendronate. Calcium in combination with cholecalciferol may help reduce the risk of falls.
Muscle weakness/pain (Grade: B)
Vitamin D deficiency has been linked to muscle weakness and pain. Strong evidence is lacking to support the use of vitamin D supplementation for pain, and more research is needed.
Osteoporosis (general) (Grade: B)
Vitamin D and calcium are used to treat people with osteoporosis, especially after a fracture, as well as to prevent osteoporosis in people who have endocrine or nutrition problems.
Renal osteodystrophy (bone problems due to chronic kidney failure) (Grade: B)
Renal osteodystrophy refers to the bone problems that occur in people with chronic kidney failure. Calcifediol or ergocalciferol taken by mouth may help prevent this condition in people with chronic kidney failure who are undergoing treatment.
Asthma (Grade: C)
People with asthma may have an increased risk of vitamin D deficiency. Vitamin D may help reduce inflammation, decrease asthma severity, and improve treatment. More studies are needed before firm conclusions can be made.
Autoimmune diseases (Grade: C)
Vitamin D may reduce inflammation and help prevent autoimmune diseases, including rheumatoid arthritis, multiple sclerosis, and Crohn's disease. However, further high-quality research is needed to confirm these results.
Bone density (children) (Grade: C)
Vitamin D improves bone density in children who are vitamin D deficient. However, results are unclear and more research is needed.
Bone diseases (kidney disease or kidney transplant) (Grade: C)
Vitamin D has been studied for people with chronic kidney disease. The use of substances similar to vitamin D has been found to increase bone density in people with kidney disease. The effect of vitamin D itself is unclear. Further research is needed before conclusions can be made.
Cancer prevention (breast, colorectal, prostate, other) (Grade: C)
Many studies have looked at the effects of vitamin D on cancer. Positive results have been reported with the use of vitamin D alone or with calcium. Vitamin D intake with or without calcium has been studied for colorectal, cervical, breast, and prostate cancer. A reduced risk of colorectal cancer has been shown with vitamin D supplementation. However, there is a lack of consistent or strong evidence. Further study is needed.
Cognition (Grade: C)
Higher blood levels of vitamin D3 are associated with better mental performance in people with Alzheimer's disease. Weekly dietary intake of vitamin D has been linked to better mental performance in older women. However, high-quality studies are still needed in this area.
Fertility (Grade: C)
Vitamin D may benefit fertility. However, more study is needed to understand its potential effects on pregnancy completion and live birth.
Fibromyalgia (long-term, body-wide pain) (Grade: C)
Vitamin D has been studied for the treatment of fibromyalgia, but evidence is lacking in support of its effectiveness. Further study is needed.
Fractures (prevention) (Grade: C)
Conflicting results have been found on the use of vitamin D for fracture prevention. The combination of alfacalcidol and alendronate has been found to reduce the risk of falls and fractures. However, further high-quality research is needed before firm conclusions can be made.
Fractures (treatment) (Grade: C)
Studies have suggested that vitamin D levels may decrease after a hip fracture, and that vitamin D may help improve these levels. However, further research is needed.
Hepatic osteodystrophy (bone disease in people with liver disease) (Grade: C)
Metabolic bone disease is common among people with chronic liver disease, and osteoporosis accounts for the majority of cases. Varying degrees of poor calcium absorption may occur in people with chronic liver disease due to malnutrition and vitamin D deficiency. Vitamin D taken by mouth or injected may play a role in the management of this condition.
High blood pressure (Grade: C)
Low levels of vitamin D may be linked to high blood pressure. Blood pressure is often higher during the winter season, at a further distance from the equator, and in people with dark skin pigmentation. However, the evidence is unclear. More research is needed in this area. People who have high blood pressure should be managed by a medical professional.
HIV (Grade: C)
There is a high prevalence of vitamin D deficiency in HIV-positive men. However, there is a lack of strong evidence to support the use of vitamin D in this population. More research is needed before a conclusion can be made.
Immune function (Grade: C)
Early research suggests that vitamin D and similar compounds, such as alfacalcidol, may impact immune function. Vitamin D added to standard therapy may benefit people with infectious disease. More studies are needed to confirm these results.
Increasing lifespan (Grade: C)
Intake of vitamin D may be linked to a longer lifespan. More evidence is needed to confirm this finding.
Inflammatory bowel disease (Grade: C)
Studies on the use of vitamin D for inflammatory bowel disease are limited. Early evidence suggests benefit for people who have Crohn's disease. More research is needed.
Kidney disease (chronic) (Grade: C)
Vitamin D has been studied for people with chronic kidney disease. However, the effects of supplementation are unclear at this time. Further research is needed before conclusions can be made.
Loose teeth (Grade: C)
Research suggests that intake levels of calcium and vitamin D aimed at preventing osteoporosis may help prevent teeth from falling out. More studies are needed before a firm conclusion can be made.
Mood disorders (Grade: C)
Some studies suggest an association between low vitamin D levels in the blood and various mood disorders, including depression, seasonal affective disorder (SAD), and premenstrual syndrome (PMS). Also vitamin D supplementation may improve symptoms of depression associated with SAD. More research is needed before a conclusion can be made.
Multiple sclerosis (MS) (Grade: C)
Vitamin D may have a protective effect on the risk of developing MS. A link has been suggested between low vitamin D and MS risk. More evidence is needed.
Muscle strength (Grade: C)
Evidence is mixed regarding the effect of vitamin D on strength in the elderly. Further research is required in order to confirm these results.
Muscle wasting/weakness (Grade: C)
Vitamin D has been studied for muscle wasting/weakness. There is insufficient evidence in this area, and further research is needed.
Myelodysplastic syndrome (disease of blood cell production) (Grade: C)
Although vitamin D is commonly used by people with myelodysplastic syndrome, there is insufficient evidence in this area.
Osteoarthritis (Grade: C)
Results have been inconclusive on the use of vitamin D for knee pain or cartilage volume loss. Further study is needed in this field before conclusions may be made.
Osteogenesis imperfecta (disorder in which bones break easily) (Grade: C)
OI is a genetic disease in which bones break easily due to a malfunction in the body's production of collagen. Proper calcium and vitamin D intake is essential to maintaining strong bones. More research is needed on the use of vitamin D for this disorder.
Osteomalacia (bone softening caused by anti-seizure drugs) (Grade: C)
Vitamin D plus calcium may help improve overall well-being in people who have seizure disorders. This combination may also improve bone mineral content when taken with anti-seizure drugs.
Osteoporosis (due to corticosteroids) (Grade: C)
Some evidence suggests that steroids may lead to problems with vitamin D metabolism, which may lead to bone loss and the development of osteoporosis associated with steroid medications. There is limited evidence that vitamin D may improve bone strength in people taking long-term steroids. Further research is needed.
Osteoporosis (due to drugs) (Grade: C)
Early study suggests that vitamin D and calcium supplementation is needed to maintain bone health in men who are receiving androgen deprivation therapy (ADT) for prostate cancer. Calcitriol and alfacalcidol have been found to significantly reduce bone mass loss caused by drugs. More research is needed.
Osteoporosis (in people with cystic fibrosis) (Grade: C)
Osteoporosis is common in people with cystic fibrosis (a build-up of mucus in the lungs). This is due to poor absorption of fat, which leads to vitamin D deficiency. Calcitriol taken by mouth appears to increase calcium absorption.
Pregnancy (Grade: C)
Evidence is conflicting on the use of vitamin D as a nutritional supplement during pregnancy. Some studies suggest potential benefit for birth weight, length, and weight, as well as reduced risk of diabetes during pregnancy. Further study is needed.
Prevention of respiratory tract infections (Grade: C)
Use of vitamin D has been found to help prevent respiratory tract infections in children. However, some conflicting results have been found in humans. Although evidence supports the effects of vitamin D on prevention of respiratory tract infections in children, further study in both adults and children is needed.
Rickets (that does not respond to treatment) (Grade: C)
Vitamin D has been studied for a form of rickets (bone weakening in children) that is associated with low phosphate levels and does not respond to treatment. More research is needed.
Seasonal affective disorder (SAD) (Grade: C)
SAD is a form of depression that occurs during the winter months, possibly due to reduced exposure to sunlight. In one study, vitamin D was found to be better than light therapy in the treatment of SAD. Further studies are necessary to confirm these findings.
Senile warts (Grade: C)
In early research, senile warts have been treated with vitamin D3 applied to the skin. Further research is needed.
Sexual dysfunction (Grade: C)
Vitamin D has been studied for sexual dysfunction. However, evidence is mixed. More research is needed before a conclusion can be made.
Skin conditions (Grade: C)
Calcipotriol (Dovonex®) is a man-made version of vitamin D3 that is often used for the treatment of plaque psoriasis (a condition causing redness and itching). Calcipotriol may also be effective for skin conditions other than psoriasis. More research is needed.
Skin pigmentation disorders (Grade: C)
Applying vitamin D3 ointment to the skin with other therapies may help treat some skin pigmentation disorders. More evidence is needed.
Stroke (Grade: C)
Higher levels of vitamin D may decrease the risk of stroke. However, further study is needed to confirm the use of vitamin D for this condition.
Tuberculosis (Grade: C)
Vitamin D has been studied for the treatment of tuberculosis. Although some benefit has been found, more research is needed in this area.
Type 1 diabetes (Grade: C)
Some studies suggest that vitamin D may help prevent the development of type 1 diabetes. However, there is a lack of strong evidence to support this finding.
Type 2 diabetes (Grade: C)
Vitamin D has mixed effects on blood sugar and insulin sensitivity. It is often studied in combination with calcium. Further research is needed to confirm these results.
Vitamin D deficiency (infants and breast feeding mothers) (Grade: C)
Early studies suggest that vitamin D may benefit both breastfeeding mothers and their babies. More research is needed to confirm these findings.
Vitiligo (irregular white patches on the skin) (Grade: C)
Results are unclear as to the effects of vitamin D and similar compounds for treating vitiligo. More research is needed before a conclusion can be made.
Weight gain (in women with menopause) (Grade: C)
Vitamin D and calcium may have an effect on weight gain in women undergoing menopause. Evidence suggests that this may be particularly true in women consuming inadequate calcium. Further research is needed.
Atopic eczema (skin condition causing itchy, scaly rashes) (Grade: D)
Studies show a lack of effect of vitamin D on symptoms of atopic eczema. Further research is needed.
Cancer treatment (prostate) (Grade: D)
Evidence suggests a lack of effect of vitamin D as a part of cancer treatment for prostate cancer. Further study is needed using other formulations of vitamin D and other types of cancer.
Heart disease (Grade: D)
Vitamin D is recognized as being important for heart health. Overall, research is not consistent, and some studies have found negative effects of vitamin D on heart health. More high-quality research is needed to make a firm conclusion.
High cholesterol (Grade: D)
Many studies have looked at the effects of vitamin D alone or in combination with other agents for high cholesterol, but results are inconsistent. Some negative effects have been reported. More research is needed on the use of vitamin D alone or in combination with calcium.