VITAMIN D: Uses, Side Effects, Interactions and Warnings

VITAMIN D Overview Information

Vitamin D is a vitamin. It can be found in small amounts in a few foods, including fatty fish such as herring, mackerel, sardines and tuna. To make vitamin D more available, it is added to dairy products, juices, and cereals that are then said to be “fortified with vitamin D.” But most vitamin D – 80% to 90% of what the body gets – is obtained through exposure to sunlight. Vitamin D can also be made in the laboratory as medicine.

Vitamin D is used for preventing and treating rickets, a disease that is caused by not having enough vitamin D (vitamin D deficiency). Vitamin D is also used for treating weak bones (osteoporosis), bone pain (osteomalacia), bone loss in people with a condition called hyperparathyroidism, and an inherited disease (osteogenesis imperfecta) in which the bones are especially brittle and easily broken. It is also used for preventing falls and fractures in people at risk for osteoporosis, and preventing low calcium and bone loss (renal osteodystrophy) in people with kidney failure.

Vitamin D is used for conditions of the heart and blood vessels, including high blood pressure and high cholesterol. It is also used for diabetes, obesity, muscle weakness, multiple sclerosis, rheumatoid arthritis, chronic obstructive pulmonary disease (COPD), asthma, bronchitis, premenstrual syndrome (PMS), and tooth and gum disease.

Some people use vitamin D for skin conditions including vitiligo, scleroderma, psoriasis, actinic keratosis, and lupus vulgaris.

It is also used for boosting the immune system, preventing autoimmune diseases, and preventing cancer.

Because vitamin D is involved in regulating the levels of minerals such as phosphorous and calcium, it is used for conditions caused by low levels of phosphorous (familial hypophosphatemia and Fanconi syndrome) and low levels of calcium (hypoparathyroidism and pseudohypoparathyroidism).

Vitamin D in forms known as calcitriol or calcipotriene is applied directly to the skin for a particular type of psoriasis.

If you travel to Canada, you may have noticed that Canada recognizes the importance of vitamin D in the prevention of osteoporosis. It allows this health claim for foods that contain calcium: "A healthy diet with adequate calcium and vitamin D, and regular physical activity, help to achieve strong bones and may reduce the risk of osteoporosis.” But the US version of this osteoporosis health claim does not yet include vitamin D.

How does it work?

Vitamin D is required for the regulation of the minerals calcium and phosphorus found in the body. It also plays an important role in maintaining proper bone structure.

Sun exposure is an easy, reliable way for most people to get vitamin D. Exposure of the hands, face, arms, and legs to sunlight two to three times a week for about one-fourth of the time it would take to develop a mild sunburn will cause the skin to produce enough vitamin D. The necessary exposure time varies with age, skin type, season, time of day, etc.

It’s amazing how quickly adequate levels of vitamin D can be restored by sunlight. Just 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 fatty fat and then released when sunlight is gone.

Nevertheless, vitamin D deficiency is more common than you might expect. People who don’t get enough sun, especially people living in Canada and the northern half of the US, are especially at risk. Vitamin D deficiency also occurs even in sunny climates, possibly because people are staying indoors more, covering up when outside, or using sunscreens consistently these days to reduce skin cancer risk.

Older people are also at risk for vitamin D deficiency. They are less likely to spend time in the sun, have fewer “receptors” in their skin that convert sunlight to vitamin D, may not get vitamin D in their diet, may have trouble absorbing vitamin D even if they do get it in their diet, and may have more trouble converting dietary vitamin D to a useful form due to aging kidneys. In fact, the risk for vitamin D deficiency in people over 65 years of age is very high. Surprisingly, as many as 40% of older people even in sunny climates such as South Florida don’t have enough vitamin D in their systems.

Vitamin D supplements may be necessary for older people, people living in northern latitudes, and for dark-skinned people who need extra time in the sun, but don’t get it.

VITAMIN D Uses & Effectiveness

Effective for:

Low levels of phosphate in the blood due to an inherited disorder called familial hypophosphatemia. 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.
Low levels of phosphate in the blood due to a disease called Fanconi syndrome. 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 blood calcium levels due to low parathyroid hormone levels. 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.
Softening of the bones (osteomalacia). 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.
Psoriasis. 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.
A bone disorder called renal osteodystrophy, which occurs in people with kidney failure. 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.
Rickets. 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 deficiency. Vitamin D is effective for preventing and treating vitamin D deficiency.

Likely Effective for:

Bone loss in people taking drugs called corticosteroids. 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.
Preventing falls in older people. Researchers have observed that 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. One study found that taking 800 IU of vitamin D reduced the risk of falling, but lower doses did not.
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.
Osteoporosis (weak bones). Taking a specific form of vitamin D called cholecalciferol (vitamin D3) along with calcium seems to help prevent bone loss and bone breaks.

Possibly Effective for:

Cancer. Some research shows that people who take a high-dose vitamin D supplement plus calcium might have a lower risk of developing certain types of cancer. However, taking vitamin D alone does not appear to reduce the risk of cancer.
Cavities. Research suggests that taking vitamin D3 (cholecalciferol) reduces the risk of cavities by 49% and vitamin D2 (ergocalciferol) reduces the risk by 36% in infants, children and adolescents.
Bone loss caused by having too much parathyroid hormone (hyperparathyroidism). Taking vitamin D (cholecalciferol) by mouth seems to reduce parathyroid hormone levels and bone loss in women with a condition called hyperparathyroidism.
Multiple sclerosis (MS). Research shows that taking vitamin D 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.
Respiratory infections. Research in school aged children shows that taking a vitamin D supplement during winter might reduce the chance of developing seasonal flu. Other research suggests that taking a vitamin D supplement might reduce the chance of an asthma attack triggered by a cold or other respiratory infection. Some additional research suggests that children with low levels of vitamin D have a higher chance of developing a respiratory infection such as the common cold or flu. However, most research suggests that vitamin D might only have an effect on respiratory infections in children. It does not appear to provide the same benefits in adults.
Rheumatoid arthritis. Research suggests that older women who consume more vitamin D from foods or supplements tend to have a lower risk of developing rheumatoid arthritis.
Tooth loss. Taking calcium and vitamin D by mouth appears to prevent tooth loss in elderly people.
Weight loss. Research shows that 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.

Possibly Ineffective for:

Breast cancer. Evidence on the effects of vitamin D on breast cancer risk is inconsistent. The best evidence comes from a large study called the Women’s Health Initiative, which found that taking 400 IU of vitamin D and 1000 mg of calcium per day does not lower the chance of getting breast cancer when taken by postmenopausal women. However, the possibility remains that high doses of vitamin D might lower breast cancer risk in younger women.
Muscle strength. Taking vitamin D (cholecalciferol) by mouth daily does not increase muscle strength or improve physicical performance in healthy older men who are not vitamin D deficient.
Bone loss in people with kidney transplants. Taking vitamin D (calcitriol) daily together with calcium carbonate does not decrease bone loss in people with kidney transplants.
Tuberculosis. Vitamin D does not appear to help cure tuberculosis infections.

Insufficient Evidence for:

Asthma. Some research suggests that people with asthma are more likely to have low vitamin D levels. In children with asthma, taking a vitamin D supplement might reduce the chance of an asthma attack during a cold or other respiratory infection. However, it is too soon to know if taking a vitamin D supplement can prevent or treat asthma symptoms.
Heart disease. Research suggests that people with low levels of vitamin D in their blood are more likely to develop heart disease, including heart failure, than people with higher vitamin D levels. However, taking vitamin D does not seem to extend the life of people with heart failure.
Kidney disease. Research suggests that 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.
Chronic obstructive pulmonary disease (COPD). Some research shows that people with COPD have lower than normal vitamin D levels. However, there is not enough information to know if taking a vitamin D supplement can decrease symptoms of COPD.
Mental function. Research shows that vitamin D levels are not linked to improved or worsened mental function.
Colorectal cancer. It is not clear if vitamin D might benefit colorectal cancer. Some research shows that calcium intake is linked with a reduced risk of developing colorectal cancer. However, this effect is not seen in people with low vitamin D levels, indicating that vitamin D might be an important factor. However, other research suggests that taking vitamin D with calcium is not associated with a lower risk of colorectal cancer.
Diabetes. Research shows that people with lower vitamin D levels are more likely to develop type 2 diabetes compared to people with higher vitamin D levels. However, there is no reliable evidence that taking vitamin D supplements can treat or prevent type 2 diabetes. Early evidence suggests that 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.
Heart failure. Some research suggests that people with low vitamin D levels have an increased risk of developing heart failure compared to those with higher vitamin D levels. However, other research shows that taking vitamin D (cholecalciferol) daily does not decrease the risk of death in people with heart failure.
High cholesterol. People with lower vitamin D levels seem to be much more likely to have high cholesterol than people with higher vitamin D levels. Limited research shows that 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. Other research suggests that vitamin D might actually increase LDL and have no beneficial effect on HDL, triglycerides, or total cholesterol.
High blood pressure. Research suggests that lower vitamin D levels are associated with a higher risk of developing high blood pressure. However, research is inconsistent. Some research suggests that vitamin D can reduce blood pressure in people with or without high blood pressure. Other research shows that taking vitamin D (cholecalciferol) daily in combination with calcium does not lower blood pressure or reduce the risk of developing high blood pressure in postmenopausal women.
Low birth weight. Research suggests that mothers who take vitamin D supplements during pregnancy have a lower risk of delivering a low birth weight infant.
Metabolic syndrome. There is conflicting evidence about the link between vitamin D and metabolic syndrome. Some research suggests that 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.
Overall death risk. Research suggests that having low vitamin D levels is associated 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.
A blood cell disease called myelodysplastic syndrome. Taking vitamin D (calcitriol or calcifediol) by mouth seems to help people with myelodysplastic syndrome.
Gum disease. Research shows that higher blood levels of vitamin D seem to be 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.
Premenstrual syndrome (PMS). There is some evidence that 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 seems to reduce PMS symptoms.
A muscle disease called proximal myopathy. Taking vitamin D (ergocalciferol) by mouth or administering it as a shot into the muscle seems to help treat a muscle disease associated with vitamin D deficiency.
Seasonal depression (seasonal affective disorder). Early research suggests that vitamin D improves symptoms of seasonal depression.
Non-cancerous wart-like growths on the skin (seborrheic keratosis). Early research suggests that applying vitamin D3 (cholecalciferol) to the skin might reduce tumor size in some people with seborrheic keratosis.
Muscle pain caused by medications called statins. Some reports suggest that taking vitamin D supplements can decrease symptoms of muscle pain in people taking statin drugs.
Vaginal atrophy. Early research shows that 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.
Warts. Reports suggest that applying maxacalcitol, which comes from vitamin D3, to the skin, can reduce viral warts in people with weakened immune systems.
Bronchitis.
Breathing disorders.
Other conditions.

More evidence is needed to rate vitamin D for these uses.

VITAMIN D Side Effects & Safety

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 POSSIBLY 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.

Special Precautions & Warnings:

Pregnancy and breast-feeding: Vitamin D is LIKELY SAFEduring pregnancy and breast-feeding when used in daily amounts below 4000 units. Do not use higher doses. Vitamin D is POSSIBLY UNSAFE when used in higher amounts during pregnancy or while breast-feeding. Using higher doses might cause serious harm to the infant.

Kidney disease: 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.

High levels of calcium in the blood: Taking vitamin D could make this condition worse.

“Hardening of the arteries” (atherosclerosis): Taking vitamin D could make this condition worse, especially in people with kidney disease.

Sarcoidosis: Vitamin D may increase calcium levels in people with sarcoidosis. This could lead to kidney stones and other problems. Use vitamin D cautiously.

Histoplasmosis: Vitamin D may increase calcium levels in people with histoplasmosis. This could lead to kidney stones and other problems. Use vitamin D cautiously.

Over-active parathyroid gland (hyperparathyroidism): Vitamin D may increase calcium levels in people with hyperparathyroidism. Use vitamin D cautiously.

Lymphoma: Vitamin D may increase calcium levels in people with lymphoma. This could lead to kidney stones and other problems. Use vitamin D cautiously.

Tuberculosis: Vitamin D might increase calcium levels in people with tuberculosis. This might result in complications such as kidney stones.

VITAMIN D Interactions

Moderate Interaction Be cautious with this combination

Aluminum interacts with VITAMIN D
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 (Dovonex) interacts with VITAMIN D
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).
Digoxin (Lanoxin) interacts with VITAMIN D
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. If you are taking digoxin (Lanoxin), talk to your doctor before taking vitamin D supplements.
Diltiazem (Cardizem, Dilacor, Tiazac) interacts with VITAMIN D
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.
Verapamil (Calan, Covera, Isoptin, Verelan) interacts with VITAMIN D
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 large amounts of vitamin D if you are taking verapamil (Calan, Covera, Isoptin, Verelan).
Water pills (Thiazide diuretics) interacts with VITAMIN D
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).

Minor Interaction Be watchful with this combination

Cimetidine (Tagamet) interacts with VITAMIN D
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 interacts with VITAMIN D
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.
Low molecular weight heparins (LMWHS) interacts with 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).

VITAMIN D Dosing

The following doses have been studied in scientific research:

BY MOUTH:

For preventing osteoporosis and fractures: 400-1000 IU per day has been used for older adults. Some experts recommended higher doses of 1000-2000 IU daily.
For preventing falls: 800-1000 IU/day has been used in combination with calcium 1000-1200 mg/day.
For preventing multiple sclerosis (MS): long-term consumption of at least 400 IU per day, mainly in the form of a multivitamin supplement, has been used.
For preventing all cancer types: calcium 1400-1500 mg/day plus vitamin D3 (cholecalciferol) 1100 IU/day in postmenopausal women has been used.
For muscle pain caused by medications called "statins": vitamin D2 (ergocalciferol) or vitamin D3 (cholecalciferol) 50,000 units once a week or 400 IU daily.
For preventing the flu: vitamin D (cholecalciferol) 1200 IU daily.

Most vitamin supplements contain only 400 IU (10 mcg) vitamin D.

The Institute of Medicine publishes recommended daily allowance (RDA), which is an estimate of the amount of vitamin D that meets the needs of most people in the population. The current RDA was set in 2010. The RDA varies based on age as follows: 1-70 years of age, 600 IU daily; 71 years and older, 800 IU daily; pregnant and lactating women, 600 IU daily. For infants ages 0-12 months, an adequate intake (AI) level of 400 IU is recommended.

Some organizations are recommending higher amounts. In 2008, the American Academy of Pediatrics increased the recommended minimum daily intake of vitamin D to 400 IU daily for all infants and children, including adolescents. Parents should not use vitamin D liquids dosed as 400 IU/drop. Giving one dropperful or mL by mistake can deliver 10,000 IU/day. The US Food and Drug Administration (FDA) will force companies to provide no more than 400 IU per dropperful in the future.

The National Osteoporosis Foundation recommends vitamin D 400 IU to 800 IU daily for adults under age 50, and 800 IU to 1000 IU daily for older adults.

The North American Menopause Society recommends 700 IU to 800 IU daily for women at risk of deficiency due to low sun (e.g., homebound, northern latitude) exposure.

Guidelines from the Osteoporosis Society of Canada recommend vitamin D 400 IU per day for people up to age 50, and 800 IU per day for people over 50. Osteoporosis Canada now recommends 400-1000 IU daily for adults under the age of 50 years and 800-2000 IU daily for adults over the age of 50 years.

The Canadian Cancer Society recommends 1000 IU/day during the fall and winter for adults in Canada. For those with a higher risk of having low vitamin D levels, this dose should be taken year round. This includes people who have dark skin, usually wear clothing that covers most of their skin, and people who are older or who don't go outside often.

Many experts now recommend using vitamin D supplements containing cholecalciferol in order to meet these intake levels. This seems to be more potent than another form of vitamin D called ergocalciferol.