Vitamin D (Calciferol)

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 2-3 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. 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 fat and then released when sunlight is gone.

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. However, even people living in sunny climates might be at risk, possibly because people are staying indoors more, covering up when outside, or using sunscreens 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, some scientists suggest that the risk for vitamin D deficiency in people over 65 years of age is very high. As many as 40% of older people living in sunny climates such as South Florida might not have optimal amounts of 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. Talk to your health care provider about whether a supplement is best for you.

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.

Low levels of phosphate in the blood due to an inherited disorder called familial hypophosphatemia.
Low levels of phosphate in the blood due to a disease called Fanconi syndrome.
Low blood calcium levels due to low parathyroid hormone levels.
Softening of the bones (osteomalacia).
A bone disorder called renal osteodystrophy.
Rickets.
Vitamin D deficiency.
Bone loss in people taking drugs called corticosteroids.
Osteoporosis (weak bones).
A type of psoriasis called plaque psoriasis.
Cavities.
Heart failure.
Bone loss caused by having too much parathyroid hormone (hyperparathyroidism).
Multiple sclerosis (MS).
Respiratory infections.
Tooth loss.

Adults

By Mouth:

For vitamin D deficiency: 50,000 IU per week for 6-12 weeks has been used. However, some patients require higher doses for longer periods of time to maintain optimal blood levels of vitamin D.

For preventing osteoporosis and fractures: 400-1000 IU/day of vitamin D in a form known as cholecalciferol has been used in older adults. Usually it is taken along with 500-1200 mg of calcium per day. Some experts recommended higher doses of 1000-2000 IU daily.

For preventing osteoporosis associated with medications called corticosteroids, much higher doses of 1,750-50,000 IU have been used for up to 12 months. Also, special forms of vitamin D have been used. For instance, 0.25-0.5 mcg/day of dihydroxycholecalciferol, 0.25-1 mcg/day of alfacalcidol, and 0.43-1.0 mcg/day of calcitriol have been used for up to 36 months.

For preventing bone loss due to use of corticosteroids: 0.25-1.0 mcg/day of vitamin D in forms known as calcitriol or alfacalcidol have been used for 6-36 months. In many cases, these forms of vitamin D are used along with calcium. Also, 50-32,000 mcg/day of vitamin D in the form of calcifediol has been used for 12 months. Finally, 1750-50,000 IU of vitamin D has been taken in daily or weekly doses for 6-12 months.

For preventing cancer: 1400-1500 mg/day of calcium plus 1100 IU/day of vitamin D in a form known as cholecalciferol has been used for up to 7 years.

For heart failure: 800 IU/day of vitamin D in a form known as cholecalciferol has been taken alone or along with 1000 mg/day of calcium for 3 years.

For bone loss caused by having too much parathyroid hormone (hyperparathyroidism): 800 IU/day of vitamin D in a form known as cholecalciferol has been used for 3 months.

Multiple sclerosis (MS): 400 IU/day of vitamin D has been used to prevent MS.

For preventing tooth loss in the elderly: 700 IU/day of vitamin D in a form known as cholecalciferol has been taken in combination with calcium 500 mg/day for 3 years.

Applied to the skin:

For a specific type of psoriasis called plaque psoriasis: A form of vitamin D known as calcipotriol has been applied to the skin alone or along with corticosteroids for up to 52 weeks. Typically calcipotriol is gen at a dose of 50 mcg/gram. Specific products used in clinical studies include Daivobet and Dovobet. These products contain 50 mcg/gram of calcipotriol and 0.5 mg/gram of betamethasone dipropionate.

As a shot:

For vitamin D deficiency: 600,000 IU of vitamin D (Arachitol, Solvay Pharma) given as a single shot into the muscle has been used.

Children

By Mouth:

For preventing respiratory tract infections: 1200 IU/day of vitamin D in a form known as cholecalciferol has been given to school-aged children during the winter to prevent the flu. Also, 500 IU/day of cholecalciferol has been used to prevent worsening of asthma symptoms caused by respiratory tract infections.

Vitamin D is 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.

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

Histoplasmosis: 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.

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.

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.

Sarcoidosis: Vitamin D may increase calcium levels in people with sarcoidosis. 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.