Updated: January 7, 2019
Vitamin D is required for the regulation of the minerals calcium and phosphorus in the body. It also plays an important role in maintaining proper bone structure.
The most reliable way for most people to get vitamin D is sun exposure. The required exposure time varies with age, skin type, season, time of day, etc. 6 days of casual sunlight exposure without sunscreen can make up for 49 days of no sunlight exposure.
Body fat acts like a kind of storage battery for vitamin D. During periods of sunlight, vitamin D is stored in fat and then released when sunlight is gone.
Vitamin D deficiency is more common in people who don't get enough sun light. Although people not living in sunny climates are at risk, even people living in sunny climates are also at risk, possibly because people are staying indoors more, covering up when outside, or using sunscreens to reduce skin cancer risk.
The risk for vitamin D deficiency in people over 65 years of age is very high. This is because of the following facts:
Taking vitamin D (calcitriol or dihydrotachysterol) by mouth along with phosphate supplements is effective for treating bone disorders in people with low levels of phosphate in the blood.
Taking vitamin D (ergocalciferol) by mouth is effective for treating low levels of phosphate in the blood due to a disease called Fanconi syndrome.
Low levels of parathyroid hormone can cause calcium levels to become too low. Taking vitamin D (dihydrotachysterol, calcitriol, or ergocalciferol) by mouth is effective for increasing calcium blood levels in people with low parathyroid hormone levels.
Taking vitamin D (cholecalciferol) is effective for treating softening of the bones. Also, taking vitamin D (calcifediol) is effective for treating softening of the bones due to liver disease. In addition, taking vitamin D (ergocalciferol) is effective for treating softening of the bones caused by medications or poor absorption syndromes.
Applying vitamin D or calcipotriene (a synthetic form of vitamin D) to the skin treats psoriasis in some people. Applying vitamin D to the skin together with cream containing drugs called corticosteroids seems to be more effective for treating psoriasis than using just vitamin D or the corticosteroid creams alone.
Taking vitamin D (calcifediol) by mouth manages low calcium levels and prevents bone loss in people with kidney failure. However, vitamin D does not appear to reduce the risk of death or bone pain in people with kidney failure.
Vitamin D is effective for preventing and treating rickets. A specific form of vitamin D, calcitriol, should be used in people with kidney failure.
Vitamin D is effective for preventing and treating vitamin D deficiency.
Taking vitamin D (calcifediol, cholecalciferol, calcitriol, or alfacalcidol) by mouth prevents bone loss in people taking drugs called corticosteroids. Taking vitamin D alone or with calcium seems to improve bone density in people with existing bone loss caused by using corticosteroids.
People who do not have enough vitamin D tend to fall more often than people who do. Taking a vitamin D supplement seems to reduce the risk of falling by up to 22%. Higher doses of vitamin D are more effective than lower doses. Taking 800 IU of vitamin D is recommended to reduced the risk of falling.
Also, vitamin D, in combination with calcium, but not calcium alone, may prevent falls by decreasing body sway and blood pressure. Taking vitamin D plus calcium seems to prevent falls more significantly in women than men and in older people living in hospitals or residential care facilities than those living in community dwellings.
Taking a specific form of vitamin D called cholecalciferol (vitamin D3) along with calcium seems to help prevent bone loss and bone breaks.
Taking vitamin D in forms known as cholecalciferol or ergocalciferol reduces the risk of cavities by 36% to 49% in infants, children and adolescents.
People with low vitamin D levels have an increased risk of developing heart failure compared to those with higher vitamin D levels. Taking vitamin D supplements, including vitamin D in a form known as cholecalciferol, may decrease the risk of death in people with heart failure.
Bone loss caused by having too much parathyroid hormone (hyperparathyroidism):
Taking vitamin D in a form known as cholecalciferol by mouth seems to reduce parathyroid hormone levels and bone loss in women with a condition called hyperparathyroidism.
Taking vitamin D long-term can reduce the risk of developing MS in women by up to 40%. Taking at least 400 IU daily, the amount typically found in a multivitamin supplement, seems to work the best.
Taking vitamin D helps prevent respiratory infections in children and adults. A respiratory infection can be the flu, a cold, or an asthma attack triggered by a cold or other infection. Also, taking vitamin D during pregnancy reduces the risk of these infections in the child after birth.
Taking calcium and vitamin D in a form known as cholecalciferol by mouth appears to prevent tooth loss in elderly people.
The following condition can be prevented and reduced by taking vitamin D:
People with Alzheimer's disease have lower blood levels of vitamin D than patients without Alzheimer's disease.
People with asthma and low blood levels of vitamin D seem to need to use an inhaler more often and have a higher risk of asthma complications. However, the role of vitamin D supplements in treating asthma is unclear. Best taking vitamin D by mouth for up to one year can reduce the rate of severe asthma attacks by about 31% to 36% in adults and children with asthma.
Taking vitamin D does not prevent bacterial vaginosis in women at high risk for sexually transmitted disease when taken along with standard therapy.
Vitamin D decreases parathyroid hormone levels in people with chronic kidney disease. However, taking vitamin D does not appear to lower the risk of death in people with kidney disease. Also taking vitamin D might increase calcium and phosphate levels in people with kidney disease.
People with COPD seem to have lower vitamin D levels that people without COPD. But there is not enough information to know if taking a vitamin D supplement can decrease symptoms of COPD.
Low vitamin D levels are linked to worse mental performance compared to high vitamin D levels. However, it is not clear if taking vitamin D can improve mental function.
It is not clear if vitamin D might benefit colorectal cancer. Vitamin D might be an important factor in preventing colorectal cancer. But other research shows that taking vitamin D with calcium doesn't lower the risk of colorectal cancer.
Giving vitamin D to people who are hospitalized in an intensive care unit with a critical illness might improve survival. The benefit of vitamin D might be limited to those people with very low vitamin D levels. More research is needed.
People with dementia have lower blood levels of vitamin D than people without dementia. However, it is not known if taking vitamin D benefits people with dementia.
People with lower vitamin D levels may be more likely to develop type 2 diabetes compared to people with higher vitamin D levels. However, evidence is unclear if taking vitamin D supplements can treat or prevent type 2 diabetes. Giving vitamin D supplements to infants daily during the first year of life is linked to a lower risk of developing type 1 diabetes later in life.
For elderly people who have low levels of vitamin D or who are at an increased risk of falling, taking 800 IU of vitamin D per day is recommended to reduce the risk of falling. These recommendations are supported by both population research and some clinical studies. People who do not have enough vitamin D tend to fall more often than people who do.
Some research shows that taking vitamin D reduces the risk of falling and the rates of falls in elderly people. Vitamin D works better when taken with calcium. There is also some speculation that vitamin D only reduces falls in people who are vitamin D deficient. For those who are at risk for vitamin D deficiency, a vitamin D supplement should still be considered.
Taking vitamin D might decrease pain in people with fibromyalgia and low vitamin D levels in the blood. However, taking vitamin D does not seem to help mood or quality of life.
People with lower vitamin D levels seem to be more likely to have high cholesterol than people with higher vitamin D levels. Taking calcium plus vitamin D daily, in combination with a low-calorie diet, significantly raises 'good'(HDL) cholesterol and lowers 'bad'(LDL) cholesterol in overweight women. However, taking calcium plus vitamin D without dietary restrictions does not reduce LDL cholesterol levels.
The effect of taking vitamin D during pregnancy on the risk of low birth weight or small gestational age birth is inconsistent. Additional studies are needed to determine who might benefit, if any, and what dose or formulation of vitamin D is optimal to prevent low weight at birth.
Women aged at least 45 years who consume high amounts of vitamin D or take vitamin D supplements do not have a lower risk of developing metabolic syndrome. However, other research suggests that higher vitamin D levels are linked to a lower risk of metabolic syndrome.
Taking vitamin D by mouth does not appear to improve muscle strength in people with sufficient blood levels of vitamin D. However, taking vitamin D by mouth, alone or in combination with calcium, may improve hip and leg muscle strength in people who have low levels of vitamin D, especially the elderly. Single injections of vitamin D do not seem to have beneficial effects.
Taking vitamin D in forms known as calcitriol or calcifediol by mouth seems to help people with myelodysplastic syndrome.
Having low vitamin D levels is linked with an increased risk of death from any cause. Some research suggests that people who take vitamin D supplements daily have a lower risk of dying. However, other research suggests that vitamin D reduces the risk of death only when taking together with calcium.
Higher blood levels of vitamin D are linked with a reduced risk of gum disease in people 50 years of age or older. However, this does not seem to be true for adults younger than 50 years. It is not known if taking vitamin D supplements reduces the risk of gum disease.
Taking vitamin D might reduce pain in people with long-term pain. More research is needed to confirm these results.
Higher levels of vitamin D have been linked to milder symptoms of Parkinson's disease. But taking vitamin D supplements doesn't seem to improve ParkinsonÃÂ¢Ã¢âÂ¬Ã¢âÂ¢s disease symptoms, although it might help prevent the disease from worsening. More studies are needed.
Taking vitamin D during pregnancy might lower the chance of preterm birth. Taking vitamin D during pregnancy might reduce the risk of developing diabetes during pregnancy. Taking vitamin D doesn't seem to prevent pre-eclampsia or pregnancy-related high blood pressure.
Taking vitamin D might improve ovulation in women with PCOS. Vitamin D taken together with metformin might improve menstrual cycle regularity but not when vitamin D is taken by itself.
Consuming more vitamin D from the diet might help to prevent PMS or reduce symptoms. Taking vitamin D supplements does not seem to prevent PMS. However taking vitamin D plus calcium might reduce PMS symptoms.
Taking vitamin D in a form known as ergocalciferol by mouth or administering it as a shot into the muscle seems to help treat a muscle disease associated with vitamin D deficiency.
Older women who consume more vitamin D from foods or supplements have a lower risk of developing rheumatoid arthritis.
Taking a large dose of vitamin D in a form known as ergocalciferol improves symptoms of seasonal depression.
Applying vitamin D in a form known as cholecalciferol to the skin might reduce tumor size in some people with seborrheic keratosis.
Taking vitamin D supplements can decrease symptoms of muscle pain in people taking statin drugs.
Taking vitamin D supplements for a least one year improves the surface of the vaginal wall. However, it does not seem to improve symptoms of vaginal atrophy.
Applying maxacalcitol, which comes from vitamin D3, to the skin, can reduce viral warts in people with weakened immune systems.
People with lower vitamin D levels are more likely to be obese than those with higher levels. Women taking calcium plus vitamin D are more likely to lose weight and maintain their weight. However, this benefit is mainly in women who did not consume enough calcium before they started taking supplements. Also, taking vitamin D only helps with weight loss when blood levels are increased in post-menopausal overweight or obese women. When vitamin D is taken by people who are overweight and normal weight, it does not seem to help with weight loss or fat loss.
Breathing disorders, Bronchitis and other conditions can be improved by taking vitamin D. But, more evidence is needed to rate vitamin D for these uses.
Vitamin D is LIKELY SAFE when taken by mouth or given as a shot into the muscle in recommended amounts. Most people do not commonly experience side effects with vitamin D, unless too much is taken.
Some side effects of taking too much vitamin D include weakness, fatigue, sleepiness, headache, loss of appetite, dry mouth, metallic taste, nausea, vomiting, and others.
Taking vitamin D for long periods of time in doses higher than 4000 units daily is considered as unsafe and may cause excessively high levels of calcium in the blood. However, much higher doses are often needed for the short-term treatment of vitamin D deficiency. This type of treatment should be done under the supervision of a healthcare provider.
Vitamin D is safe during pregnancy and breast-feeding when used in daily amounts below 4000 units. It is unsafe when used in higher amounts then recommended dose during pregnancy or while breast-feeding. Using higher doses might cause serious harm to the infant.
Taking vitamin D could make hardening of the arteries worse, especially in people with kidney disease.
Vitamin D may increase calcium levels in people with histoplasmosis. This could lead to kidney stones and other problems. Use vitamin D cautiously.
High levels of calcium in the blood:
Taking vitamin D could make this condition worse.
Vitamin D may increase calcium levels in people with hyperparathyroidism. So, use vitamin D cautiously.
Vitamin D may increase calcium levels in people with lymphoma. This could lead to kidney stones and other problems. So, use vitamin D cautiously.
Vitamin D may increase calcium levels and increase the risk of hardening of the arteries in people with serious kidney disease. This must be balanced with the need to prevent renal osteodystrophy, a bone disease that occurs when the kidneys fail to maintain the proper levels of calcium and phosphorus in the blood. Calcium levels should be monitored carefully in people with kidney disease.
Vitamin D may increase calcium levels in people with sarcoidosis. This could lead to kidney stones and other problems. Use vitamin D cautiously.
Vitamin D might increase calcium levels in people with tuberculosis. This might result in complications such as kidney stones.
Aluminum is found in most antacids. Vitamin D can increase how much aluminum the body absorbs. This interaction might be a problem for people with kidney disease. Take vitamin D two hours before, or four hours after antacids.
Calcipotriene is a drug that is similar to vitamin D. Taking vitamin D along with calcipotriene (Dovonex) might increase the effects and side effects of calcipotriene (Dovonex). Avoid taking vitamin D supplements if you are taking calcipotriene (Dovonex).
Vitamin D helps your body absorb calcium. Calcium can affect the heart. Digoxin (Lanoxin) is used to help your heart beat stronger. Taking vitamin D along with digoxin (Lanoxin) might increase the effects of digoxin (Lanoxin) and lead to an irregular heartbeat. Talk to your doctor before taking vitamin D supplements if you are taking digoxin (Lanoxin).
Vitamin D helps your body absorb calcium. Calcium can affect your heart. Diltiazem (Cardizem, Dilacor, Tiazac) can also affect your heart. Taking large amounts of vitamin D along with diltiazem (Cardizem, Dilacor, Tiazac) might decrease the effectiveness of diltiazem.
Vitamin D helps your body absorb calcium. Calcium can affect the heart. Verapamil (Calan, Covera, Isoptin, Verelan) can also affect the heart. Do not take more of vitamin D if you are taking verapamil (Calan, Covera, Isoptin, Verelan).
Vitamin D helps your body absorb calcium. Some 'water pills' increase the amount of calcium in the body. Taking large amounts of vitamin D along with some 'water pills' might cause to be too much calcium in the body. This could cause serious side effects including kidney problems.
Some of these 'water pills' include chlorothiazide (Diuril), hydrochlorothiazide (HydroDIURIL, Esidrix), indapamide (Lozol), metolazone (Zaroxolyn), and chlorthalidone (Hygroton).
The body changes vitamin D into a form that it can use. Cimetidine might decrease how well the body changes vitamin D. This might decrease how well vitamin D works. But this interaction probably isn't important for most people.
Heparin slows blood clotting and can increase the risk of breaking a bone when used for a long period of time. People taking these medications should eat a diet rich in calcium and vitamin D.
Some medications called low molecular weight heparins can increase the risk of breaking a bone when used for a long periods of time. People taking these medications should eat a diet rich in calcium and vitamin D. These drugs include enoxaparin (Lovenox), dalteparin (Fragmin), and tinzaparin (Innohep).